stress: implement tools/stress/device-observer

[elitegreg]

Why

Independent sampler that writes the breaking-point sentinel the orchestrator polls. Splitting from the orchestrator keeps abort logic out of the sweep path.

See Notion design for full context.

Scope

Create tools/stress/device-observer/.

• CLI flags (per doc): --dut-host, --eapi-user, --eapi-pass, --agent-metrics-url, --sample-interval (default 10s), --abort-file, --working-dir.
• Every --sample-interval (eAPI commands, JSON output): show hardware capacity | json, show gre tunnel static | json, show processes top once | json, show logging errors, show logging critical. One file per sample named <command>-<iso8601>.json.
• Every --sample-interval: scrape --agent-metrics-url; append rows to observer.agent_metrics.json as {t_ns, metric_name, value, labels_json}.
• Continuous tail: parse non-config-commit EOS log entries into observer.logging.json as {t_ns, severity, facility, message}. Also scan <working-dir>/orchestrator.agent.log for the abort-trigger strings below.
• Abort triggers (write <working-dir>/abort once on first match; include reason):
  • Provision (t_submit → t_agent_applied) p95 over the active batch window > 30 s, or any single user > 30 s.
  • Deprovision p95 > 30 s.
  • Switch CPU > 80% sustained over any 60 s window.
  • doublezero_agent_apply_config_errors_total increments within a sample.
  • doublezero_agent_get_config_errors_total increments within a sample.
  • Agent log: "could not get diff because /usr/bin/Cli command timed out after 60 seconds".
  • Agent log: "not overriding lock since its age is less than" (any occurrence — already a clear race signal).
  • Agent log silent for > 15 s.
  • Ledger unreachable for > 30 s (signaled by orchestrator writing a heartbeat the observer can read, or a direct RPC probe — choose one; recommend the heartbeat approach to avoid duplicating RPC config).

Acceptance

• Sampling produces the expected files on a local cEOS dz1 in < 30 s; JSON validates.
• Each abort trigger has a unit test using a fixture log / fake eAPI response.
• Manual: cause a fake CPU spike (e.g., fixture-injected show processes JSON) and confirm sentinel is written within one sample interval.

Tracker: #3744.

[nikw9944]

System Prompt

Roadbike Assignment

You are a Claude Code instance managed by Roadbike. You are one of
potentially many instances working in parallel across different GitHub issues and repos.
Other instances may be working on related issues in the same or different repositories
at the same time. If you encounter a dependency on work being done in another issue,
note it in your work plan and proceed with what you can accomplish independently.

Assignment

Issue #3747: stress: implement tools/stress/device-observer
Repository: malbeclabs/doublezero
Branch: nikw9944/doublezero-3747 (created for you, or create it if it doesn't exist)
URL: #3747

Issue Description

## Why

Independent sampler that writes the breaking-point sentinel the orchestrator polls. Splitting from the orchestrator keeps abort logic out of the sweep path.

See Notion design for full context.

Scope

Create tools/stress/device-observer/.

• CLI flags (per doc): --dut-host, --eapi-user, --eapi-pass, --agent-metrics-url, --sample-interval (default 10s), --abort-file, --working-dir.
• Every --sample-interval (eAPI commands, JSON output): show hardware capacity | json, show gre tunnel static | json, show processes top once | json, show logging errors, show logging critical. One file per sample named <command>-<iso8601>.json.
• Every --sample-interval: scrape --agent-metrics-url; append rows to observer.agent_metrics.json as {t_ns, metric_name, value, labels_json}.
• Continuous tail: parse non-config-commit EOS log entries into observer.logging.json as {t_ns, severity, facility, message}. Also scan <working-dir>/orchestrator.agent.log for the abort-trigger strings below.
• Abort triggers (write <working-dir>/abort once on first match; include reason):
  • Provision (t_submit → t_agent_applied) p95 over the active batch window > 30 s, or any single user > 30 s.
  • Deprovision p95 > 30 s.
  • Switch CPU > 80% sustained over any 60 s window.
  • doublezero_agent_apply_config_errors_total increments within a sample.
  • doublezero_agent_get_config_errors_total increments within a sample.
  • Agent log: "could not get diff because /usr/bin/Cli command timed out after 60 seconds".
  • Agent log: "not overriding lock since its age is less than" (any occurrence — already a clear race signal).
  • Agent log silent for > 15 s.
  • Ledger unreachable for > 30 s (signaled by orchestrator writing a heartbeat the observer can read, or a direct RPC probe — choose one; recommend the heartbeat approach to avoid duplicating RPC config).

Acceptance

• Sampling produces the expected files on a local cEOS dz1 in < 30 s; JSON validates.
• Each abort trigger has a unit test using a fixture log / fake eAPI response.
• Manual: cause a fake CPU spike (e.g., fixture-injected show processes JSON) and confirm sentinel is written within one sample interval.

Tracker: #3744.

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[nikw9944]

Work Plan (Revision 0)

Work Plan (Revision 0)

Work Plan — Issue #3747

stress: implement tools/stress/device-observer

Tracker: #3744 — GRE Tunnel Capacity Study

Summary

Build a standalone Go binary at tools/stress/device-observer/ that runs alongside
the (separate) device-orchestrator during a GRE-tunnel-capacity sweep on an
isolated Arista DUT. The observer is an independent sampler: it polls the DUT
over eAPI, scrapes the agent's Prometheus metrics, tails EOS syslog and the
orchestrator's captured agent log, and — on the first sign of a defined fault —
writes a sentinel file (<working-dir>/abort) that the orchestrator polls to halt
the sweep. Splitting this from the orchestrator keeps the breaking-point detection
logic out of the sweep path and lets either side be replaced/restarted
independently.

Approach

Top-level shape

A single cmd/device-observer/main.go parses flags, opens the eAPI client and
metrics scraper, opens output writers, and starts a small set of goroutines that
share a context.Context and a single "abort decider" channel:

• eAPI sampler — every --sample-interval runs the five show ... commands
  and writes one <command>-<iso8601>.json file per sample.
• Metrics scraper — every --sample-interval GETs --agent-metrics-url,
  parses with prometheus/common/expfmt, appends one row per metric+labels
  combo to observer.agent_metrics.json (NDJSON).
• EOS log tail — every --sample-interval runs show logging last <window>,
  parses each non-config-commit line, dedupes against a moving window, appends
  rows to observer.logging.json (NDJSON).
• Agent-log tail — tail -F-style read of
  <working-dir>/orchestrator.agent.log, emitting matches for the two trigger
  strings + tracking time-since-last-line for the agent-silence trigger.
• Run-log reader — re-reads <working-dir>/orchestrator-runlog.json
  (NDJSON) on each sample tick to recompute provision / deprovision p95 over the
  active batch window.
• Heartbeat watcher — checks mtime of a ledger-heartbeat file the
  orchestrator updates (preferred over duplicating RPC config, as the issue
  recommends).
• Abort decider — consumes signals from the above, evaluates the trigger
  list, writes <working-dir>/abort exactly once with a JSON body
  {reason, t_ns, trigger} and sets a sticky internal flag so further signals
  are no-ops.

All file writes go to --working-dir. NDJSON (one JSON object per line) is
used for the append-mostly outputs because it survives crash/SIGINT cleanly and
is trivial to validate.

Output formats

All output is JSON:

• Sample files: one per command per sample interval, named
  <command-slug>-<iso8601>.json (slug examples:
  show-hardware-capacity, show-gre-tunnel-static, show-processes-top,
  show-logging-errors, show-logging-critical). Body is the raw eAPI
  response for | json commands; the two show logging {errors,critical}
  outputs are wrapped as {"raw": "<stdout>"} since they are not native JSON.
• observer.agent_metrics.json (NDJSON):
  {"t_ns": ..., "metric_name": "...", "value": ..., "labels_json": "{...}"}.
• observer.logging.json (NDJSON):
  {"t_ns": ..., "severity": "...", "facility": "...", "message": "..."}.
• observer-config.json (one-shot): full CLI options snapshot, written at
  startup for reproducibility (mirrors orchestrator-config.json).
• abort sentinel: written once on first trigger, body
  {"t_ns": ..., "trigger": "<key>", "reason": "<human-readable>"}.

Key design choices and why

• Use github.com/aristanetworks/goeapi — already a dependency
  (go.mod:9), already used by e2e/internal/devnet/device.go:889 to talk to
  cEOS, supports HTTP/HTTPS basic-auth eAPI directly. Avoids reimplementing
  JSON-RPC ourselves.
• Don't depend on the agent's gRPC eAPI proxy (aristapb.EapiMgrService).
  That requires the agent to be up — but the whole point of the observer is to
  watch the agent. Direct eAPI is independent.
• Tail orchestrator.agent.log via file polling, not pipe — the file is
  written by the orchestrator (stress: implement tools/stress/device-orchestrator #3746); observer must work even if it's started
  after the orchestrator. A tail -F-style reader handles rotation/recreate.
  golang.org/x/sys is already available; we can implement a tiny in-process
  tailer (open + seek-to-end + periodic poll) without adding a dep.
• Reuse the existing MetricsClient (e2e/internal/prometheus/metrics.go)
  pattern but inline a smaller version under tools/stress/device-observer/
  to keep the tool self-contained (the e2e helper isn't easily importable from
  outside the e2e tree and carries unnecessary dependencies).
• Ledger heartbeat over direct RPC probe — the issue recommends the
  heartbeat approach; orchestrator already has the RPC config, observer
  should not duplicate it. The contract: orchestrator writes
  <working-dir>/ledger.heartbeat with the current time on every successful
  RPC call; observer watches its mtime and triggers if older than 30 s. The
  orchestrator side of this contract is its own work (stress: implement tools/stress/device-orchestrator #3746) — the observer
  should still function (without the ledger trigger) if the file is absent.
• Provision/deprovision p95 from orchestrator-runlog.json — the
  orchestrator emits one row per event (submit / applied / deprovision_*); the
  observer pairs them by user_pubkey and computes t_agent_applied - t_submit. Only the active batch window matters: pairs whose applied
  ts falls inside the most-recent batch window (between the last batch start
  and now). The observer infers batch boundaries from a submit row whose
  n_after_event resets / advances to the next batch (interpretation here is
  conservative: a 60-second "no new submits" gap rolls the window).
• CPU sustained-over-60s check — keep a ring of (t_ns, cpu%) samples
  from show processes top once | json, parse cpuTotal.cpuUsage (the
  field name needs verification against a real cEOS sample at implementation
  time — fall back to summing per-process CPU if the field is absent). If
  every sample in the most-recent 60 s exceeds 80%, trigger.
• Counter-increment triggers — keep last-seen values for
  doublezero_agent_apply_config_errors_total and
  doublezero_agent_get_config_errors_total; trigger if current > previous
  on any scrape.
• Sentinel writes once — a sync.Once plus an os.OpenFile(..., O_CREATE|O_EXCL, ...) ensures the file is only written once even if
  multiple triggers fire in the same tick.

Module layout

The existing tools/twamp/ lives inside the root Go module
(github.com/malbeclabs/doublezero — go.mod:1). Follow the same pattern; do
not create a separate Go module. Imports will be
github.com/malbeclabs/doublezero/tools/stress/device-observer/....

Files to Change

Sub-issue decomposition follows in the "Estimated Scope" section. The list
below is the union across all chunks.

New (code)

• tools/stress/device-observer/cmd/device-observer/main.go — CLI flags
  (--dut-host, --eapi-user, --eapi-pass, --agent-metrics-url,
  --sample-interval default 10s, --abort-file, --working-dir), signal
  handling, goroutine wiring, config snapshot writer.
• tools/stress/device-observer/internal/eapi/client.go — thin wrapper around
  goeapi.Connect exposing RunShowJSON(cmd) ([]byte, error) and
  RunShowText(cmd) (string, error).
• tools/stress/device-observer/internal/sample/eos.go — sample loop;
  per-tick runs the five show ... commands, writes
  <command>-<iso8601>.json files into --working-dir.
• tools/stress/device-observer/internal/promscrape/scrape.go — fetches
  --agent-metrics-url, parses with expfmt.NewTextParser, appends NDJSON
  rows to observer.agent_metrics.json. Surfaces last counter values to the
  abort decider via a small Snapshot() accessor.
• tools/stress/device-observer/internal/loggingtail/eos.go — show logging last <window> poller, splits + parses standard EOS syslog format (timestamp,
  severity, facility, message), filters out config-commit noise
  (%SYS-5-CONFIG_E, %SYS-5-CONFIG_I), dedupes, writes NDJSON rows.
• tools/stress/device-observer/internal/loggingtail/agent.go — file-based
  tail -F for <working-dir>/orchestrator.agent.log; emits typed events
  (AgentLineSeen, CliTimeout, LockRaceObserved).
• tools/stress/device-observer/internal/runlog/reader.go — re-reads
  orchestrator-runlog.json (NDJSON), pairs submit/applied/deprovision rows
  by user_pubkey, exposes ProvisionDurations(), DeprovisionDurations(),
  and ActiveBatchWindow().
• tools/stress/device-observer/internal/abort/decider.go — central
  state-machine: takes signals from all collectors, holds the rolling
  windows (60 s CPU ring, agent-silence timer, ledger-heartbeat watcher),
  computes p95 helpers, writes the sentinel file once with reason.

New (tests)

• tools/stress/device-observer/internal/eapi/client_test.go
• tools/stress/device-observer/internal/sample/eos_test.go (fixture eAPI
  response → expected files)
• tools/stress/device-observer/internal/promscrape/scrape_test.go (fixture
  exposition format → expected NDJSON rows + counter snapshot)
• tools/stress/device-observer/internal/loggingtail/eos_test.go (fixture
  show logging output → expected rows)
• tools/stress/device-observer/internal/loggingtail/agent_test.go (fixture
  agent log → expected matches)
• tools/stress/device-observer/internal/runlog/reader_test.go
• tools/stress/device-observer/internal/abort/decider_test.go — one test
  per abort trigger, each with a fixture:
  • provision p95 > 30s
  • provision single user > 30s
  • deprovision p95 > 30s
  • CPU sustained > 80% for 60s
  • apply_config_errors increment
  • get_config_errors increment
  • agent log Cli timeout
  • agent log lock race
  • agent silent > 15s
  • ledger heartbeat stale > 30s

New (docs)

• tools/stress/device-observer/README.md — flags, output files, abort
  triggers, contract with the orchestrator (abort sentinel,
  ledger.heartbeat, orchestrator-runlog.json,
  orchestrator.agent.log).
• docs/work-plan-3747.md — this file.

Modified

• CHANGELOG.md — one Unreleased bullet per merged sub-issue, under a new
  "Tools" section if one doesn't exist, otherwise extend.
• CLAUDE.md — only if a non-obvious workflow needs to be captured (likely
  not — the new tool is documented by its own README).
• README.md — likely no change (root README is intentionally terse).

No existing source files outside tools/stress/device-observer/ need to change.

Risks & Considerations

• eAPI JSON shape drift across EOS versions. show processes top once | json and show hardware capacity | json differ between cEOS variants and
  the physical 7130LBR / 7280CR3A targets. Mitigation: write the raw eAPI
  response to disk verbatim (per the issue) and only parse the specific
  field used by the CPU trigger. All other fields are recorded for
  post-hoc analysis. Add a unit test with a captured fixture from local cEOS
  dz1.
• show logging is not native JSON. Wrap as {"raw": "..."} for the
  sample-file output, and separately parse it for the tail rows. Don't
  conflate the two.
• Orchestrator runlog read race. The orchestrator writes NDJSON one line at
  a time; the observer reads the whole file each tick. Use a byte-offset
  resumption (track last-seen offset) to avoid re-parsing rows already seen.
  Tolerate partial trailing lines.
• Heartbeat file may not exist on startup. The observer should not trigger
  ledger unreachable until at least one heartbeat has been seen — otherwise
  starting the observer before the orchestrator would always trip the alarm.
  Use a "grace period until first heartbeat" rule.
• Sentinel idempotency. sync.Once + O_CREATE|O_EXCL ensures one write.
  If a stale abort file exists from a prior run, the observer should refuse
  to start (or require a --force flag) so we don't conflate runs.
• Sample-interval drift. Use time.Ticker, not time.Sleep, so slow eAPI
  calls don't cumulatively shift the schedule. If a tick fires while the
  previous sample is still running, skip the tick and log a warning.
• Provision-window inference. "Active batch window" isn't defined
  rigorously in the issue. Proposed rule: window = [t_now - 2*hold_seconds, t_now], clamped to start at the most recent batch boundary. Document this
  in README.md and flag for review in the abort-decider PR.
• No new external deps. Everything needed (goeapi, expfmt,
  prometheus/common, slog) is already in go.mod.

Testing Strategy

• Unit tests — one per abort trigger (see file list). Each test
  constructs the decider with fixture inputs and asserts the sentinel is /
  isn't written, with the expected reason string.
• Sampler integration check (manual + scripted) — point the binary at
  dz-local-device-dz1 (admin/admin eAPI) for 30 s and assert the five
  expected file kinds appear and parse as JSON. The first sub-issue's PR
  description includes the exact docker exec/go run invocation.
• Prom scrape integration check — point at the running cEOS dz1's agent
  metrics endpoint (devnet exposes one) and assert observer.agent_metrics.json
  has rows for the documented metric names.
• Abort-trigger manual (per acceptance criterion): inject a fake
  show processes top once fixture with cpuUsage: 95, run a 90 s window,
  confirm abort appears within one sample interval after the 60 s threshold.
• No e2e test in this issue — the device-stress e2e is tracked separately
  (e2e: add device_stress_physical_test.go #3726 in the parent tracker). Unit-test coverage of each trigger is the
  acceptance contract.

Estimated Scope

Total new code (excluding tests/docs): ~700–900 lines. Substantially over
the 250-line per-PR threshold. Recommend splitting into the following
sub-issues, each independently mergeable and reviewable.

Sub-issue	Title	Est. code LOC	Outputs
3747-1	stress/device-observer: scaffolding + eAPI device sampler	~200	Binary builds; running it produces the five <command>-<iso8601>.json files per --sample-interval.
3747-2	stress/device-observer: agent Prometheus scrape	~150	observer.agent_metrics.json populates correctly; counter snapshot accessible internally.
3747-3	stress/device-observer: EOS syslog + agent-log tail	~200	observer.logging.json populated; agent log matchers emit typed events.
3747-4	stress/device-observer: abort decider + sentinel	~200	<working-dir>/abort sentinel written on first matching trigger; one unit test per trigger.

Each chunk leaves the binary in a working, runnable state with the previously
shipped behavior intact. Chunk 1 ships the skeleton (with no-op stubs where
later chunks plug in); chunks 2–4 fill in real implementations behind those
stubs.

Operator decision needed

Per Roadbike change-size policy, please confirm:

1. Should I file the four sub-issues now (3747-1 … 3747-4), and what
   metadata (milestone, labels, assignees) should they carry? The
   parent [TRACKER] GRE Tunnel Capacity Study #3744 carries milestone "Device Stress Test" and no labels;
   sibling stress: implement tools/stress/device-orchestrator #3746 is assigned to @elitegreg. Default proposal: same milestone,
   no labels, assignee @nikw9944, link each as a child of stress: implement tools/stress/device-observer #3747.
2. Implementation order — proposed: 1 → 2 → 3 → 4 (each builds on the
   previous), but 2 and 3 are independent of each other after 1 lands and
   could go in either order or in parallel.
3. Should stress: implement tools/stress/device-observer #3747 itself be re-scoped to the scaffolding chunk (and the
   other three filed as separate issues), or kept as the umbrella and closed
   only when all four land?

Open Questions

• show processes top once | json field path for total CPU% — need to
  capture a real cEOS sample to confirm the exact field (cpuTotal.cpuUsage?
  usage.total?). Will be resolved during chunk 4 implementation with a
  fixture captured from dz-local-device-dz1.
• Batch-window definition for p95 — the issue says "p95 over the active
  batch window" but doesn't define the window boundaries. Proposed default
  (above) needs sign-off; alternative is to have the orchestrator emit
  explicit batch_start / batch_end events in orchestrator-runlog.json.
• --abort-file flag default — the spec lists it as a flag; default
  should be <working-dir>/abort to make the orchestrator/observer pair
  trivially compatible. Confirm.

[nikw9944]

Work Log — waiting_review

Good — goeapi is already a dep. Let me look at the orchestrator that this issue refers to, and the broader stress tooling context (issue #3744 tracker).

Now I have a good handle on the project structure. Let me check the existing tools/twamp Makefile for patterns and see if tools/ has its own go.mod somewhere:

I have enough context to write the work plan. The observer is a substantial new tool; let me create the docs directory and plan.

Work Plan — Issue #3747

stress: implement tools/stress/device-observer — saved to docs/work-plan-3747.md.

Summary

Build a standalone Go binary at tools/stress/device-observer/ that runs alongside the (separate) device-orchestrator during a GRE-tunnel-capacity sweep on an isolated Arista DUT. The observer is an independent sampler: it polls the DUT over eAPI, scrapes the agent's Prometheus metrics, tails EOS syslog and the orchestrator's captured agent log, and — on the first sign of a defined fault — writes a sentinel file (<working-dir>/abort) the orchestrator polls to halt the sweep.

Approach

A single cmd/device-observer/main.go parses flags, opens the eAPI client and metrics scraper, opens output writers, and starts a small set of goroutines sharing one context.Context and one abort-decider channel:

• eAPI sampler — time.Ticker every --sample-interval; writes one <command>-<iso8601>.json per command per tick.
• Metrics scraper — expfmt.NewTextParser; appends NDJSON rows to observer.agent_metrics.json and exposes a counter snapshot to the decider.
• EOS log tail — periodic show logging last <window> poll, filters config-commit noise, dedupes by hash, appends NDJSON rows to observer.logging.json.
• Agent-log tail — in-process tail -F of <working-dir>/orchestrator.agent.log; emits typed events for the two trigger strings + tracks time-since-last-line for the agent-silence trigger.
• Run-log reader — re-reads orchestrator-runlog.json NDJSON with byte-offset resumption; pairs submit/applied/deprovision rows by user_pubkey to compute p95s.
• Heartbeat watcher — watches mtime of <working-dir>/ledger.heartbeat (orchestrator writes it on every successful RPC); avoids duplicating RPC config per the issue's recommendation.
• Abort decider — central state machine; writes <working-dir>/abort exactly once via sync.Once + O_CREATE|O_EXCL, with a JSON body {t_ns, trigger, reason}.

Key design choices

• Use github.com/aristanetworks/goeapi — already in go.mod (line 9), already used by e2e/internal/devnet/device.go:889. Avoids reinventing JSON-RPC.
• Don't depend on the agent's gRPC eAPI proxy — the whole point of the observer is to watch the agent, so it must work independently.
• No new external deps — goeapi, expfmt, prometheus/common, slog are all already present.
• Heartbeat over direct RPC probe for the ledger trigger, as the issue recommends.
• Sentinel idempotency — sticky flag prevents double-trigger; observer refuses to start if a stale abort file exists from a prior run.

Files to Change

New code:

• tools/stress/device-observer/cmd/device-observer/main.go
• tools/stress/device-observer/internal/eapi/client.go
• tools/stress/device-observer/internal/sample/eos.go
• tools/stress/device-observer/internal/promscrape/scrape.go
• tools/stress/device-observer/internal/loggingtail/eos.go
• tools/stress/device-observer/internal/loggingtail/agent.go
• tools/stress/device-observer/internal/runlog/reader.go
• tools/stress/device-observer/internal/abort/decider.go

Tests — one per package, plus one test per abort trigger in abort/decider_test.go (10 triggers total).

Docs: tools/stress/device-observer/README.md, this work plan.

Modified: CHANGELOG.md (one Unreleased bullet per sub-issue). Lives inside the root Go module — no new go.mod.

Risks & Considerations

• eAPI JSON shape drift between cEOS and physical 7130LBR / 7280CR3A — record raw responses verbatim; only parse the one field used by the CPU trigger; cover with a captured-fixture unit test.
• show logging is text, not JSON — wrap as {"raw": "..."} in the per-sample file but parse separately for the tail rows.
• Orchestrator runlog read race — byte-offset resumption + tolerate partial trailing lines.
• Heartbeat may not exist at startup — grace period until first heartbeat seen, otherwise starting observer before orchestrator would always trip.
• "Active batch window" not rigorously defined — proposed default [t_now - 2*hold_seconds, t_now] clamped to most recent batch boundary; flagged as Open Question.
• show processes top once | json field path — needs a captured fixture to confirm at implementation time.

Testing Strategy

• Unit tests per abort trigger (10 total) — each constructs the decider with fixture inputs, asserts sentinel/reason.
• Sampler integration check — point binary at dz-local-device-dz1 for 30 s, assert five expected file kinds appear and parse as JSON (acceptance criterion).
• Prom scrape integration check — point at devnet cEOS dz1's agent metrics endpoint.
• Manual CPU-spike check (acceptance criterion) — inject cpuUsage: 95 fixture and confirm abort appears within one sample interval after the 60 s threshold.
• No e2e test in this issue — device-stress e2e is tracked separately (e2e: add device_stress_physical_test.go #3726).

Estimated Scope

~700–900 lines of code (excluding tests/docs) — substantially over the 250-line per-PR Roadbike threshold. Recommend splitting into four sub-issues:

Sub-issue	Title	Est. LOC	Acceptance
3747-1	scaffolding + eAPI device sampler	~200	Binary builds; five <command>-<iso8601>.json per sample interval against local cEOS.
3747-2	agent Prometheus scrape	~150	observer.agent_metrics.json populates; counter snapshot accessible to decider stub.
3747-3	EOS syslog + agent-log tail	~200	observer.logging.json populates; agent-log matchers emit typed events.
3747-4	abort decider + sentinel	~200	Sentinel written on first matching trigger; one unit test per trigger.

Each chunk leaves the binary runnable. Chunks 2 and 3 are independent of each other after 1 lands and could be done in parallel.

Operator decision needed

1. File the four sub-issues now? With what metadata? Default proposal: milestone "Device Stress Test" (matches [TRACKER] GRE Tunnel Capacity Study #3744/stress: implement tools/stress/device-orchestrator #3746), no labels, assignee @nikw9944, linked as children of stress: implement tools/stress/device-observer #3747.
2. Implementation order — proposed 1 → 2 → 3 → 4; 2 and 3 are parallelizable after 1 lands.
3. Should stress: implement tools/stress/device-observer #3747 itself be re-scoped to the scaffolding chunk, or kept as the umbrella and closed only when all four land?

Open Questions

• Exact show processes top once | json field path for total CPU% — resolve during chunk 4 with a real cEOS fixture.
• Rigorous "active batch window" definition — proposed default flagged for review; alternative is to have the orchestrator (stress: implement tools/stress/device-orchestrator #3746) emit explicit batch_start/batch_end events.
• Default value for --abort-file flag — proposed <working-dir>/abort for trivial orchestrator/observer pairing.

STATUS: COMPLETE — Plan written to docs/work-plan-3747.md. The estimated scope (~700–900 LOC) exceeds the 250-line policy, so the plan proposes a four-way split with operator decisions called out. No source files were modified.

--- Result: success | Session cost: $2.1406 | Turns: 45 | Tokens: 50 in / 20090 out | 2026-05-22 16:09:04 UTC ---

[nikw9944]

Roadbike Operator Feedback

Action: Plan revision requested (Revision 1)
Instance: #4477

Here's sample output of show processes top once | json:

{
    "timeInfo": {
        "currentTime": 1779478316.872492,
        "upTime": 340405.24,
        "users": 1,
        "loadAvg": [
            2.07,
            1.84,
            1.86
        ]
    },
    "threadsStateInfo": {
        "total": 380,
        "run": 1,
        "sleep": 379,
        "stop": 0,
        "zombie": 0
    },
    "cpuInfo": {
        "%Cpu(s)": {
            "user": 1.1,
            "system": 0.8,
            "nice": 0.0,
            "idle": 97.3,
            "ioWait": 0.0,
            "hwIrq": 0.4,
            "swIrq": 0.4,
            "stolen": 0.0
        }
    },
    "memInfo": {
        "physicalMem": {
            "memTotal": 32687411,
            "memUsed": 6278246,
            "memFree": 22808371,
            "memBuffer": 5159424
        },
        "swapMem": {
            "memTotal": 0,
            "memUsed": 0,
            "memFree": 0,
            "memBuffer": 26409267
        }
    },
    "processes": {
        "8211": {
            "cmd": "SandMact",
            "userName": "root",
            "priority": "20",
            "niceValue": 0,
            "virtMem": "8748740",
            "residentMem": "174804",
            "sharedMem": "153436",
            "status": "S",
            "cpuPctType": "{:.1f}",
            "cpuPct": 12.5,
            "memPct": 0.5,
            "activeTime": 974663
        },
        ...
    }
}

Do you not need sample output for any of the other show commands?

Regarding batch-window definition, let's start with your proposed default.

Regarding the --abort-file flag, sure, let's use your suggested default.

For show logging, you observed that this is not native JSON. That's correct, and I don't see any benefit it wrapping it in JSON. Let's just store it in a plain text file.

Does the observer need to read the whole file on each tick? When can't it read it tail -f style?

[nikw9944]

Work Plan (Revision 1)

Work Plan (Revision 1)

Work Plan — Issue #3747

stress: implement tools/stress/device-observer

Tracker: #3744 — GRE Tunnel Capacity Study

Summary

Build a standalone Go binary at tools/stress/device-observer/ that runs alongside
the (separate) device-orchestrator during a GRE-tunnel-capacity sweep on an
isolated Arista DUT. The observer is an independent sampler: it polls the DUT
over eAPI, scrapes the agent's Prometheus metrics, tails EOS syslog and the
orchestrator's captured agent log, and — on the first sign of a defined fault —
writes a sentinel file (<working-dir>/abort) that the orchestrator polls to halt
the sweep. Splitting this from the orchestrator keeps the breaking-point detection
logic out of the sweep path and lets either side be replaced/restarted
independently.

Approach

Top-level shape

A single cmd/device-observer/main.go parses flags, opens the eAPI client and
metrics scraper, opens output writers, and starts a small set of goroutines that
share a context.Context and a single "abort decider" channel:

• eAPI sampler — every --sample-interval runs the five show ... commands
  and writes one <command>-<iso8601>.json file per sample.
• Metrics scraper — every --sample-interval GETs --agent-metrics-url,
  parses with prometheus/common/expfmt, appends one row per metric+labels
  combo to observer.agent_metrics.json (NDJSON).
• EOS log tail — every --sample-interval runs show logging last <window>,
  parses each non-config-commit line, dedupes against a moving window, appends
  rows to observer.logging.json (NDJSON).
• Agent-log tail — tail -F-style read of
  <working-dir>/orchestrator.agent.log, emitting matches for the two trigger
  strings + tracking time-since-last-line for the agent-silence trigger.
• Run-log reader — re-reads <working-dir>/orchestrator-runlog.json
  (NDJSON) on each sample tick to recompute provision / deprovision p95 over the
  active batch window.
• Heartbeat watcher — checks mtime of a ledger-heartbeat file the
  orchestrator updates (preferred over duplicating RPC config, as the issue
  recommends).
• Abort decider — consumes signals from the above, evaluates the trigger
  list, writes <working-dir>/abort exactly once with a JSON body
  {reason, t_ns, trigger} and sets a sticky internal flag so further signals
  are no-ops.

All file writes go to --working-dir. NDJSON (one JSON object per line) is
used for the append-mostly outputs because it survives crash/SIGINT cleanly and
is trivial to validate.

Output formats

All output is JSON:

• Sample files: one per command per sample interval, named
  <command-slug>-<iso8601>.json (slug examples:
  show-hardware-capacity, show-gre-tunnel-static, show-processes-top,
  show-logging-errors, show-logging-critical). Body is the raw eAPI
  response for | json commands; the two show logging {errors,critical}
  outputs are wrapped as {"raw": "<stdout>"} since they are not native JSON.
• observer.agent_metrics.json (NDJSON):
  {"t_ns": ..., "metric_name": "...", "value": ..., "labels_json": "{...}"}.
• observer.logging.json (NDJSON):
  {"t_ns": ..., "severity": "...", "facility": "...", "message": "..."}.
• observer-config.json (one-shot): full CLI options snapshot, written at
  startup for reproducibility (mirrors orchestrator-config.json).
• abort sentinel: written once on first trigger, body
  {"t_ns": ..., "trigger": "<key>", "reason": "<human-readable>"}.

Key design choices and why

• Use github.com/aristanetworks/goeapi — already a dependency
  (go.mod:9), already used by e2e/internal/devnet/device.go:889 to talk to
  cEOS, supports HTTP/HTTPS basic-auth eAPI directly. Avoids reimplementing
  JSON-RPC ourselves.
• Don't depend on the agent's gRPC eAPI proxy (aristapb.EapiMgrService).
  That requires the agent to be up — but the whole point of the observer is to
  watch the agent. Direct eAPI is independent.
• Tail orchestrator.agent.log via file polling, not pipe — the file is
  written by the orchestrator (stress: implement tools/stress/device-orchestrator #3746); observer must work even if it's started
  after the orchestrator. A tail -F-style reader handles rotation/recreate.
  golang.org/x/sys is already available; we can implement a tiny in-process
  tailer (open + seek-to-end + periodic poll) without adding a dep.
• Reuse the existing MetricsClient (e2e/internal/prometheus/metrics.go)
  pattern but inline a smaller version under tools/stress/device-observer/
  to keep the tool self-contained (the e2e helper isn't easily importable from
  outside the e2e tree and carries unnecessary dependencies).
• Ledger heartbeat over direct RPC probe — the issue recommends the
  heartbeat approach; orchestrator already has the RPC config, observer
  should not duplicate it. The contract: orchestrator writes
  <working-dir>/ledger.heartbeat with the current time on every successful
  RPC call; observer watches its mtime and triggers if older than 30 s. The
  orchestrator side of this contract is its own work (stress: implement tools/stress/device-orchestrator #3746) — the observer
  should still function (without the ledger trigger) if the file is absent.
• Provision/deprovision p95 from orchestrator-runlog.json — the
  orchestrator emits one row per event (submit / applied / deprovision_*); the
  observer pairs them by user_pubkey and computes t_agent_applied - t_submit. Only the active batch window matters: pairs whose applied
  ts falls inside the most-recent batch window (between the last batch start
  and now). The observer infers batch boundaries from a submit row whose
  n_after_event resets / advances to the next batch (interpretation here is
  conservative: a 60-second "no new submits" gap rolls the window).
• CPU sustained-over-60s check — keep a ring of (t_ns, cpu%) samples
  from show processes top once | json, parse cpuTotal.cpuUsage (the
  field name needs verification against a real cEOS sample at implementation
  time — fall back to summing per-process CPU if the field is absent). If
  every sample in the most-recent 60 s exceeds 80%, trigger.
• Counter-increment triggers — keep last-seen values for
  doublezero_agent_apply_config_errors_total and
  doublezero_agent_get_config_errors_total; trigger if current > previous
  on any scrape.
• Sentinel writes once — a sync.Once plus an os.OpenFile(..., O_CREATE|O_EXCL, ...) ensures the file is only written once even if
  multiple triggers fire in the same tick.

Module layout

The existing tools/twamp/ lives inside the root Go module
(github.com/malbeclabs/doublezero — go.mod:1). Follow the same pattern; do
not create a separate Go module. Imports will be
github.com/malbeclabs/doublezero/tools/stress/device-observer/....

Files to Change

Sub-issue decomposition follows in the "Estimated Scope" section. The list
below is the union across all chunks.

New (code)

• tools/stress/device-observer/cmd/device-observer/main.go — CLI flags
  (--dut-host, --eapi-user, --eapi-pass, --agent-metrics-url,
  --sample-interval default 10s, --abort-file, --working-dir), signal
  handling, goroutine wiring, config snapshot writer.
• tools/stress/device-observer/internal/eapi/client.go — thin wrapper around
  goeapi.Connect exposing RunShowJSON(cmd) ([]byte, error) and
  RunShowText(cmd) (string, error).
• tools/stress/device-observer/internal/sample/eos.go — sample loop;
  per-tick runs the five show ... commands, writes
  <command>-<iso8601>.json files into --working-dir.
• tools/stress/device-observer/internal/promscrape/scrape.go — fetches
  --agent-metrics-url, parses with expfmt.NewTextParser, appends NDJSON
  rows to observer.agent_metrics.json. Surfaces last counter values to the
  abort decider via a small Snapshot() accessor.
• tools/stress/device-observer/internal/loggingtail/eos.go — show logging last <window> poller, splits + parses standard EOS syslog format (timestamp,
  severity, facility, message), filters out config-commit noise
  (%SYS-5-CONFIG_E, %SYS-5-CONFIG_I), dedupes, writes NDJSON rows.
• tools/stress/device-observer/internal/loggingtail/agent.go — file-based
  tail -F for <working-dir>/orchestrator.agent.log; emits typed events
  (AgentLineSeen, CliTimeout, LockRaceObserved).
• tools/stress/device-observer/internal/runlog/reader.go — re-reads
  orchestrator-runlog.json (NDJSON), pairs submit/applied/deprovision rows
  by user_pubkey, exposes ProvisionDurations(), DeprovisionDurations(),
  and ActiveBatchWindow().
• tools/stress/device-observer/internal/abort/decider.go — central
  state-machine: takes signals from all collectors, holds the rolling
  windows (60 s CPU ring, agent-silence timer, ledger-heartbeat watcher),
  computes p95 helpers, writes the sentinel file once with reason.

New (tests)

• tools/stress/device-observer/internal/eapi/client_test.go
• tools/stress/device-observer/internal/sample/eos_test.go (fixture eAPI
  response → expected files)
• tools/stress/device-observer/internal/promscrape/scrape_test.go (fixture
  exposition format → expected NDJSON rows + counter snapshot)
• tools/stress/device-observer/internal/loggingtail/eos_test.go (fixture
  show logging output → expected rows)
• tools/stress/device-observer/internal/loggingtail/agent_test.go (fixture
  agent log → expected matches)
• tools/stress/device-observer/internal/runlog/reader_test.go
• tools/stress/device-observer/internal/abort/decider_test.go — one test
  per abort trigger, each with a fixture:
  • provision p95 > 30s
  • provision single user > 30s
  • deprovision p95 > 30s
  • CPU sustained > 80% for 60s
  • apply_config_errors increment
  • get_config_errors increment
  • agent log Cli timeout
  • agent log lock race
  • agent silent > 15s
  • ledger heartbeat stale > 30s

New (docs)

• tools/stress/device-observer/README.md — flags, output files, abort
  triggers, contract with the orchestrator (abort sentinel,
  ledger.heartbeat, orchestrator-runlog.json,
  orchestrator.agent.log).
• docs/work-plan-3747.md — this file.

Modified

• CHANGELOG.md — one Unreleased bullet per merged sub-issue, under a new
  "Tools" section if one doesn't exist, otherwise extend.
• CLAUDE.md — only if a non-obvious workflow needs to be captured (likely
  not — the new tool is documented by its own README).
• README.md — likely no change (root README is intentionally terse).

No existing source files outside tools/stress/device-observer/ need to change.

Risks & Considerations

• eAPI JSON shape drift across EOS versions. show processes top once | json and show hardware capacity | json differ between cEOS variants and
  the physical 7130LBR / 7280CR3A targets. Mitigation: write the raw eAPI
  response to disk verbatim (per the issue) and only parse the specific
  field used by the CPU trigger. All other fields are recorded for
  post-hoc analysis. Add a unit test with a captured fixture from local cEOS
  dz1.
• show logging is not native JSON. Wrap as {"raw": "..."} for the
  sample-file output, and separately parse it for the tail rows. Don't
  conflate the two.
• Orchestrator runlog read race. The orchestrator writes NDJSON one line at
  a time; the observer reads the whole file each tick. Use a byte-offset
  resumption (track last-seen offset) to avoid re-parsing rows already seen.
  Tolerate partial trailing lines.
• Heartbeat file may not exist on startup. The observer should not trigger
  ledger unreachable until at least one heartbeat has been seen — otherwise
  starting the observer before the orchestrator would always trip the alarm.
  Use a "grace period until first heartbeat" rule.
• Sentinel idempotency. sync.Once + O_CREATE|O_EXCL ensures one write.
  If a stale abort file exists from a prior run, the observer should refuse
  to start (or require a --force flag) so we don't conflate runs.
• Sample-interval drift. Use time.Ticker, not time.Sleep, so slow eAPI
  calls don't cumulatively shift the schedule. If a tick fires while the
  previous sample is still running, skip the tick and log a warning.
• Provision-window inference. "Active batch window" isn't defined
  rigorously in the issue. Proposed rule: window = [t_now - 2*hold_seconds, t_now], clamped to start at the most recent batch boundary. Document this
  in README.md and flag for review in the abort-decider PR.
• No new external deps. Everything needed (goeapi, expfmt,
  prometheus/common, slog) is already in go.mod.

Testing Strategy

• Unit tests — one per abort trigger (see file list). Each test
  constructs the decider with fixture inputs and asserts the sentinel is /
  isn't written, with the expected reason string.
• Sampler integration check (manual + scripted) — point the binary at
  dz-local-device-dz1 (admin/admin eAPI) for 30 s and assert the five
  expected file kinds appear and parse as JSON. The first sub-issue's PR
  description includes the exact docker exec/go run invocation.
• Prom scrape integration check — point at the running cEOS dz1's agent
  metrics endpoint (devnet exposes one) and assert observer.agent_metrics.json
  has rows for the documented metric names.
• Abort-trigger manual (per acceptance criterion): inject a fake
  show processes top once fixture with cpuUsage: 95, run a 90 s window,
  confirm abort appears within one sample interval after the 60 s threshold.
• No e2e test in this issue — the device-stress e2e is tracked separately
  (e2e: add device_stress_physical_test.go #3726 in the parent tracker). Unit-test coverage of each trigger is the
  acceptance contract.

Estimated Scope

Total new code (excluding tests/docs): ~700–900 lines. Substantially over
the 250-line per-PR threshold. Recommend splitting into the following
sub-issues, each independently mergeable and reviewable.

Sub-issue	Title	Est. code LOC	Outputs
3747-1	stress/device-observer: scaffolding + eAPI device sampler	~200	Binary builds; running it produces the five <command>-<iso8601>.json files per --sample-interval.
3747-2	stress/device-observer: agent Prometheus scrape	~150	observer.agent_metrics.json populates correctly; counter snapshot accessible internally.
3747-3	stress/device-observer: EOS syslog + agent-log tail	~200	observer.logging.json populated; agent log matchers emit typed events.
3747-4	stress/device-observer: abort decider + sentinel	~200	<working-dir>/abort sentinel written on first matching trigger; one unit test per trigger.

Each chunk leaves the binary in a working, runnable state with the previously
shipped behavior intact. Chunk 1 ships the skeleton (with no-op stubs where
later chunks plug in); chunks 2–4 fill in real implementations behind those
stubs.

Operator decision needed

Per Roadbike change-size policy, please confirm:

1. Should I file the four sub-issues now (3747-1 … 3747-4), and what
   metadata (milestone, labels, assignees) should they carry? The
   parent [TRACKER] GRE Tunnel Capacity Study #3744 carries milestone "Device Stress Test" and no labels;
   sibling stress: implement tools/stress/device-orchestrator #3746 is assigned to @elitegreg. Default proposal: same milestone,
   no labels, assignee @nikw9944, link each as a child of stress: implement tools/stress/device-observer #3747.
2. Implementation order — proposed: 1 → 2 → 3 → 4 (each builds on the
   previous), but 2 and 3 are independent of each other after 1 lands and
   could go in either order or in parallel.
3. Should stress: implement tools/stress/device-observer #3747 itself be re-scoped to the scaffolding chunk (and the
   other three filed as separate issues), or kept as the umbrella and closed
   only when all four land?

Open Questions

• show processes top once | json field path for total CPU% — need to
  capture a real cEOS sample to confirm the exact field (cpuTotal.cpuUsage?
  usage.total?). Will be resolved during chunk 4 implementation with a
  fixture captured from dz-local-device-dz1.
• Batch-window definition for p95 — the issue says "p95 over the active
  batch window" but doesn't define the window boundaries. Proposed default
  (above) needs sign-off; alternative is to have the orchestrator emit
  explicit batch_start / batch_end events in orchestrator-runlog.json.
• --abort-file flag default — the spec lists it as a flag; default
  should be <working-dir>/abort to make the orchestrator/observer pair
  trivially compatible. Confirm.

[nikw9944]

Work Log — waiting_review

STATUS: COMPLETE — Revised plan written to docs/work-plan-3747.md.

The full revised plan:

Work Plan — Issue #3747 (Revision 1)

stress: implement tools/stress/device-observer

Tracker: #3744 — GRE Tunnel Capacity Study

Revision Notes

Revision 1 addresses operator feedback on revision 0:

• CPU trigger field path resolved. show processes top once | json exposes total CPU as cpuInfo["%Cpu(s)"].idle (a percentage). Total = 100 - idle. We can also cross-check against user + system + nice + hwIrq + swIrq + stolen. Open question on this resolved; no fixture-capture step needed.
• No sample output needed for the other commands. We store the raw eAPI response verbatim for show hardware capacity | json and show gre tunnel static | json — no parsing of specific fields, so we don't need a captured fixture to write the code. (The unit test for the sampler still uses a synthetic fixture to assert file naming + content round-trip.)
• show logging outputs are plain text. Filenames are show-logging-errors-<iso8601>.log and show-logging-critical-<iso8601>.log. No JSON wrapping. The separate parsed-syslog stream remains NDJSON because it carries structured fields (timestamp, severity, facility, message) that the decider consumes.
• Runlog reader is tail-style, not full-file-per-tick. Same pattern as the agent-log tailer: open once, track byte offset, poll for new bytes, buffer partial trailing lines, handle truncation/rotation. The decider keeps an in-memory rolling map of pending submit events keyed by user_pubkey, and pairs each applied / deprovision_applied event against that map as it arrives. Closed pairs are appended to a bounded ring used for p95.
• Batch-window definition: confirmed default ([t_now - 2*hold_seconds, t_now], clamped at the last batch boundary).
• --abort-file default: confirmed (<working-dir>/abort).

Summary

Build a standalone Go binary at tools/stress/device-observer/ that runs alongside the (separate) device-orchestrator during a GRE-tunnel-capacity sweep on an isolated Arista DUT. The observer is an independent sampler: it polls the DUT over eAPI, scrapes the agent's Prometheus metrics, tails EOS syslog and the orchestrator's captured agent log, and — on the first sign of a defined fault — writes a sentinel file (<working-dir>/abort) that the orchestrator polls to halt the sweep. Splitting this from the orchestrator keeps the breaking-point detection logic out of the sweep path and lets either side be replaced/restarted independently.

Approach

Top-level shape

A single cmd/device-observer/main.go parses flags, opens the eAPI client and metrics scraper, opens output writers, and starts a small set of goroutines that share a context.Context and a single "abort decider" channel:

• eAPI sampler — every --sample-interval runs the five show ... commands and writes one file per sample. JSON commands → <command>-<iso8601>.json. Text show logging {errors,critical} → <command>-<iso8601>.log.
• Metrics scraper — every --sample-interval GETs --agent-metrics-url, parses with prometheus/common/expfmt, appends one row per metric+labels combo to observer.agent_metrics.json (NDJSON).
• EOS log tail — every --sample-interval runs show logging last <window>, parses each non-config-commit line, dedupes against a moving window, appends rows to observer.logging.json (NDJSON).
• Agent-log tail — file-poll, tail -F-style read of <working-dir>/orchestrator.agent.log, emitting matches for the two trigger strings + tracking time-since-last-line for the agent-silence trigger.
• Run-log tail — file-poll, tail -F-style read of <working-dir>/orchestrator-runlog.json (NDJSON). Maintains an in-memory map of pending submit events keyed by user_pubkey; on each applied / deprovision_applied event pairs the duration and appends it to a bounded ring used to compute provision / deprovision p95 over the active batch window.
• Heartbeat watcher — checks mtime of a ledger-heartbeat file the orchestrator updates (preferred over duplicating RPC config, as the issue recommends).
• Abort decider — consumes signals from the above, evaluates the trigger list, writes <working-dir>/abort exactly once with a JSON body {reason, t_ns, trigger} and sets a sticky internal flag so further signals are no-ops.

All file writes go to --working-dir. NDJSON is used for the append-mostly structured outputs because it survives crash/SIGINT cleanly and is trivial to validate. The show logging * per-sample files are plain text (eAPI returns plain text for those).

Output formats

• Sample files:
  • JSON commands: one file per command per sample interval, named <command-slug>-<iso8601>.json. Slugs: show-hardware-capacity, show-gre-tunnel-static, show-processes-top. Body is the raw eAPI response.
  • Text commands: show-logging-errors-<iso8601>.log, show-logging-critical-<iso8601>.log. Body is the raw eAPI text output verbatim, no wrapping.
• observer.agent_metrics.json (NDJSON): {"t_ns": ..., "metric_name": "...", "value": ..., "labels_json": "{...}"}.
• observer.logging.json (NDJSON): {"t_ns": ..., "severity": "...", "facility": "...", "message": "..."}.
• observer-config.json (one-shot): full CLI options snapshot, written at startup for reproducibility (mirrors orchestrator-config.json).
• abort sentinel: written once on first trigger, body {"t_ns": ..., "trigger": "<key>", "reason": "<human-readable>"}.

CPU trigger — exact field path

Confirmed against the operator-supplied sample:

"cpuInfo": {
  "%Cpu(s)": {
    "user": 1.1, "system": 0.8, "nice": 0.0,
    "idle": 97.3, "ioWait": 0.0,
    "hwIrq": 0.4, "swIrq": 0.4, "stolen": 0.0
  }
}

Compute cpu_total = 100 - idle per sample. Maintain a ring keyed by t_ns covering at least 60 s. Trigger when every sample in the trailing 60 s has cpu_total > 80%. (Equivalent: trigger when min over the trailing-60 s window > 80%.)

Key design choices and why

• Use github.com/aristanetworks/goeapi — already a dependency (go.mod), already used by e2e/internal/devnet/device.go to talk to cEOS, supports HTTP/HTTPS basic-auth eAPI directly. Avoids reimplementing JSON-RPC ourselves.

• Don't depend on the agent's gRPC eAPI proxy (aristapb.EapiMgrService). That requires the agent to be up — but the whole point of the observer is to watch the agent. Direct eAPI is independent.

• Tail orchestrator output files via file polling, not pipe. Both orchestrator.agent.log and orchestrator-runlog.json are tailed by the same small in-process tailer (open + seek-to-end + periodic poll + handle truncation/recreate by checking inode/size). The observer must work even if it's started after the orchestrator and must tolerate rotation. Implemented once, reused twice.

• Reuse the existing MetricsClient pattern but inline a smaller version under tools/stress/device-observer/ (the e2e helper isn't easily importable and carries unnecessary dependencies).

• Ledger heartbeat over direct RPC probe — the issue recommends the heartbeat approach; orchestrator already has the RPC config, observer should not duplicate it. Contract: orchestrator writes <working-dir>/ledger.heartbeat with the current time on every successful RPC call; observer watches its mtime and triggers if older than 30 s. The orchestrator side of this contract is its own work (stress: implement tools/stress/device-orchestrator #3746) — the observer should still function (without the ledger trigger) if the file is absent, with a "grace period until first heartbeat" rule so it never trips on cold-start.

• Runlog tail with in-memory pending-submit map — orchestrator emits rows in order: a submit row first, then a later applied row with the same user_pubkey. As tail-style reads pull new lines:

  • submit → insert into pending[user_pubkey] = t_submit.
  • applied → t_applied - pending[user_pubkey] → append to provision-p95 ring; delete from pending.
  • deprovision_submit / deprovision_applied → same pattern against a second map / ring.

  This avoids re-scanning the file on every tick and avoids re-parsing rows we've already seen. The decider re-evaluates p95 every sample tick against the current ring contents.

• Sentinel writes once — a sync.Once plus an os.OpenFile(..., O_CREATE|O_EXCL, ...) ensures the file is only written once even if multiple triggers fire in the same tick.

Module layout

The existing tools/twamp/ lives inside the root Go module (github.com/malbeclabs/doublezero). Follow the same pattern; do not create a separate Go module. Imports will be github.com/malbeclabs/doublezero/tools/stress/device-observer/....

Files to Change

Sub-issue decomposition follows in the "Estimated Scope" section. The list below is the union across all chunks.

New (code)

• tools/stress/device-observer/cmd/device-observer/main.go — CLI flags (--dut-host, --eapi-user, --eapi-pass, --agent-metrics-url, --sample-interval default 10s, --abort-file default <working-dir>/abort, --working-dir), signal handling, goroutine wiring, config snapshot writer.
• tools/stress/device-observer/internal/eapi/client.go — thin wrapper around goeapi.Connect exposing RunShowJSON(cmd) ([]byte, error) and RunShowText(cmd) (string, error).
• tools/stress/device-observer/internal/sample/eos.go — sample loop; per-tick runs the five show ... commands, writes <command-slug>-<iso8601>.{json,log} files into --working-dir. Also surfaces the parsed CPU-total value to the abort decider via a small channel/accessor (avoid double-fetching the same response).
• tools/stress/device-observer/internal/tailer/tailer.go — generic file-poll tailer used by both the agent-log and the runlog readers (open + offset + recreate/truncate detection + partial-line buffer).
• tools/stress/device-observer/internal/promscrape/scrape.go — fetches --agent-metrics-url, parses with expfmt.NewTextParser, appends NDJSON rows to observer.agent_metrics.json. Surfaces last counter values to the abort decider via a small Snapshot() accessor.
• tools/stress/device-observer/internal/loggingtail/eos.go — show logging last <window> poller, splits + parses standard EOS syslog format (timestamp, severity, facility, message), filters out config-commit noise (%SYS-5-CONFIG_E, %SYS-5-CONFIG_I), dedupes, writes NDJSON rows.
• tools/stress/device-observer/internal/loggingtail/agent.go — uses tailer.Tailer against <working-dir>/orchestrator.agent.log; emits typed events (AgentLineSeen, CliTimeout, LockRaceObserved).
• tools/stress/device-observer/internal/runlog/reader.go — uses tailer.Tailer against <working-dir>/orchestrator-runlog.json. Owns pending-submit maps and bounded duration rings. Exposes ProvisionDurations(window), DeprovisionDurations(window), and per-event channels the decider can subscribe to.
• tools/stress/device-observer/internal/abort/decider.go — central state-machine: takes signals from all collectors, holds the rolling windows (60 s CPU ring, agent-silence timer, ledger-heartbeat watcher), computes p95 helpers, writes the sentinel file once with reason.

New (tests)

• tools/stress/device-observer/internal/eapi/client_test.go
• tools/stress/device-observer/internal/sample/eos_test.go — fixture eAPI response → expected files; covers both JSON and .log output paths and asserts CPU-total computation from operator's sample.
• tools/stress/device-observer/internal/tailer/tailer_test.go — covers append, partial trailing line, truncation, recreate.
• tools/stress/device-observer/internal/promscrape/scrape_test.go — fixture exposition format → expected NDJSON rows + counter snapshot.
• tools/stress/device-observer/internal/loggingtail/eos_test.go — fixture show logging output → expected rows.
• tools/stress/device-observer/internal/loggingtail/agent_test.go — fixture agent log appended in chunks → expected matches.
• tools/stress/device-observer/internal/runlog/reader_test.go — fixture NDJSON appended in chunks → expected paired durations; out-of-order applied before submit ignored gracefully.
• tools/stress/device-observer/internal/abort/decider_test.go — one test per abort trigger, each with a fixture:
  • provision p95 > 30s
  • provision single user > 30s
  • deprovision p95 > 30s
  • CPU sustained > 80% for 60s (using operator's sample shape)
  • apply_config_errors increment
  • get_config_errors increment
  • agent log Cli timeout
  • agent log lock race
  • agent silent > 15s
  • ledger heartbeat stale > 30s (with grace-period rule)

New (docs)

• tools/stress/device-observer/README.md — flags, output files, abort triggers, contract with the orchestrator (abort sentinel, ledger.heartbeat, orchestrator-runlog.json, orchestrator.agent.log).
• docs/work-plan-3747.md — this file.

Modified

• CHANGELOG.md — one Unreleased bullet per merged sub-issue, under a new "Tools" section if one doesn't exist, otherwise extend.

No existing source files outside tools/stress/device-observer/ need to change.

Risks & Considerations

• eAPI JSON shape drift across EOS versions. show hardware capacity | json and show gre tunnel static | json differ between cEOS variants and the physical 7130LBR / 7280CR3A targets. Mitigation: write the raw eAPI response to disk verbatim (per the issue) and only parse the specific field used by the CPU trigger, which is now known (cpuInfo["%Cpu(s)"].idle). All other fields are recorded for post-hoc analysis.
• show logging is not native JSON. Per operator feedback: store the raw text verbatim as .log files; do not wrap in JSON. The separately parsed syslog stream (observer.logging.json) is the structured view used by the decider.
• Tailer correctness. Both runlog and agent-log readers must handle: appends, partial trailing lines (no newline yet), file truncation (new run starts), file recreation (orchestrator restart), and the file not existing yet at startup. All four cases get a tailer-level unit test.
• Out-of-order runlog events. If the observer is started mid-run, the first applied it sees may have no matching submit in its in-memory map. Ignore those events for p95 purposes (don't synthesize a pair from partial data).
• Heartbeat file may not exist on startup. The observer should not trigger ledger unreachable until at least one heartbeat has been seen — otherwise starting the observer before the orchestrator would always trip the alarm. Use a "grace period until first heartbeat" rule.
• Sentinel idempotency. sync.Once + O_CREATE|O_EXCL ensures one write. If a stale abort file exists from a prior run, the observer should refuse to start (or require a --force flag) so we don't conflate runs.
• Sample-interval drift. Use time.Ticker, not time.Sleep, so slow eAPI calls don't cumulatively shift the schedule. If a tick fires while the previous sample is still running, skip the tick and log a warning.
• Provision-window definition — confirmed by operator: window = [t_now - 2*hold_seconds, t_now], clamped at the most recent batch boundary. Documented in README.
• No new external deps. Everything needed (goeapi, expfmt, prometheus/common, slog) is already in go.mod.

Testing Strategy

• Unit tests — one per abort trigger (see file list). Each test constructs the decider with fixture inputs and asserts the sentinel is / isn't written, with the expected reason string.
• Tailer tests — append, partial line, truncation, recreate; reused by agent-log and runlog readers.
• Sampler integration check (manual + scripted) — point the binary at dz-local-device-dz1 (admin/admin eAPI) for 30 s and assert the five expected file kinds appear and parse (JSON files parse as JSON; .log files are non-empty text). The first sub-issue's PR description includes the exact docker exec/go run invocation.
• Prom scrape integration check — point at the running cEOS dz1's agent metrics endpoint (devnet exposes one) and assert observer.agent_metrics.json has rows for the documented metric names.
• Abort-trigger manual (per acceptance criterion): inject a fake show processes top once fixture with idle: 5.0, run a 90 s window, confirm abort appears within one sample interval after the 60 s threshold.
• No e2e test in this issue — the device-stress e2e is tracked separately (e2e: add device_stress_physical_test.go #3726 in the parent tracker). Unit-test coverage of each trigger is the acceptance contract.

Estimated Scope

Total new code (excluding tests/docs): ~700–900 lines. Substantially over the 250-line per-PR threshold. Recommend splitting into the following sub-issues, each independently mergeable and reviewable.

Sub-issue	Title	Est. code LOC	Outputs
3747-1	stress/device-observer: scaffolding + eAPI device sampler	~200	Binary builds; running it produces the five per-sample files (.json for JSON commands, .log for show logging *).
3747-2	stress/device-observer: agent Prometheus scrape	~150	observer.agent_metrics.json populates correctly; counter snapshot accessible internally.
3747-3	stress/device-observer: EOS syslog + tail-based readers (agent log, runlog)	~250	observer.logging.json populated; agent-log matchers emit typed events; runlog reader emits paired durations. Includes the shared tailer package.
3747-4	stress/device-observer: abort decider + sentinel	~200	<working-dir>/abort sentinel written on first matching trigger; one unit test per trigger.

Each chunk leaves the binary in a working, runnable state with the previously shipped behavior intact. Chunk 1 ships the skeleton (with no-op stubs where later chunks plug in); chunks 2–4 fill in real implementations behind those stubs.

Operator decision needed

Per Roadbike change-size policy, please confirm:

1. Should I file the four sub-issues now (3747-1 … 3747-4), and what metadata (milestone, labels, assignees) should they carry? The parent [TRACKER] GRE Tunnel Capacity Study #3744 carries milestone "Device Stress Test" and no labels; sibling stress: implement tools/stress/device-orchestrator #3746 is assigned to @elitegreg. Default proposal: same milestone, no labels, assignee @nikw9944, link each as a child of stress: implement tools/stress/device-observer #3747.
2. Implementation order — proposed: 1 → 2 → 3 → 4 (each builds on the previous), but 2 and 3 are independent of each other after 1 lands and could go in either order or in parallel.
3. Should stress: implement tools/stress/device-observer #3747 itself be re-scoped to the scaffolding chunk (and the other three filed as separate issues), or kept as the umbrella and closed only when all four land?

Open Questions

(All previous open questions resolved by operator feedback in this revision. None outstanding.)

--- Result: success | Session cost: $0.9653 | Turns: 6 | Tokens: 11 in / 24461 out | 2026-05-22 19:47:18 UTC ---

[nikw9944]

Roadbike Operator Feedback

Action: Plan revision requested (Revision 2)
Instance: #4477

Decisions:

1. Yes, please create the issues with same milestone and project, no labels, assignee @nikw9944, and link each as a child of stress: implement tools/stress/device-observer #3747.
2. Implementation order: sure, let's do it in your proposed order. And let's make a stack of PRs, where PR 1 targets main, PR 2 targets PR 1's branch, PR 3 targets PR2's branch, and PR 4 targets PR3's branch.
3. Keep stress: implement tools/stress/device-observer #3747 as the umbrella

[nikw9944]

Work Plan (Revision 2)

Work Plan (Revision 2)

Work Plan — Issue #3747 (Revision 1)

stress: implement tools/stress/device-observer

Tracker: #3744 — GRE Tunnel Capacity Study

Revision Notes

Revision 1 addresses operator feedback on revision 0:

• CPU trigger field path resolved. show processes top once | json exposes
  total CPU as cpuInfo["%Cpu(s)"].idle (a percentage). Total = 100 - idle.
  We can also cross-check against user + system + nice + hwIrq + swIrq + stolen.
  Open question on this resolved; no fixture-capture step needed.
• No sample output needed for the other commands. We store the raw eAPI
  response verbatim for show hardware capacity | json and show gre tunnel static | json — no parsing of specific fields, so we don't need a captured
  fixture to write the code. (The unit test for the sampler still uses a
  synthetic fixture to assert file naming + content round-trip.)
• show logging outputs are plain text. Filenames are
  show-logging-errors-<iso8601>.log and show-logging-critical-<iso8601>.log.
  No JSON wrapping. The separate parsed-syslog stream remains NDJSON because
  it carries structured fields (timestamp, severity, facility, message) that
  the decider consumes.
• Runlog reader is tail-style, not full-file-per-tick. Same pattern as the
  agent-log tailer: open once, track byte offset, poll for new bytes, buffer
  partial trailing lines, handle truncation/rotation. The decider keeps an
  in-memory rolling map of pending submit events keyed by user_pubkey, and
  pairs each applied / deprovision_applied event against that map as it
  arrives. Closed pairs are appended to a bounded ring used for p95.
• Batch-window definition: confirmed default ([t_now - 2*hold_seconds, t_now], clamped at the last batch boundary).
• --abort-file default: confirmed (<working-dir>/abort).

Summary

Build a standalone Go binary at tools/stress/device-observer/ that runs
alongside the (separate) device-orchestrator during a GRE-tunnel-capacity
sweep on an isolated Arista DUT. The observer is an independent sampler:
it polls the DUT over eAPI, scrapes the agent's Prometheus metrics, tails EOS
syslog and the orchestrator's captured agent log, and — on the first sign of
a defined fault — writes a sentinel file (<working-dir>/abort) that the
orchestrator polls to halt the sweep. Splitting this from the orchestrator
keeps the breaking-point detection logic out of the sweep path and lets either
side be replaced/restarted independently.

Approach

Top-level shape

A single cmd/device-observer/main.go parses flags, opens the eAPI client and
metrics scraper, opens output writers, and starts a small set of goroutines that
share a context.Context and a single "abort decider" channel:

• eAPI sampler — every --sample-interval runs the five show ... commands
  and writes one file per sample. JSON commands → <command>-<iso8601>.json.
  Text show logging {errors,critical} → <command>-<iso8601>.log.
• Metrics scraper — every --sample-interval GETs --agent-metrics-url,
  parses with prometheus/common/expfmt, appends one row per metric+labels
  combo to observer.agent_metrics.json (NDJSON).
• EOS log tail — every --sample-interval runs show logging last <window>,
  parses each non-config-commit line, dedupes against a moving window, appends
  rows to observer.logging.json (NDJSON).
• Agent-log tail — file-poll, tail -F-style read of
  <working-dir>/orchestrator.agent.log, emitting matches for the two trigger
  strings + tracking time-since-last-line for the agent-silence trigger.
• Run-log tail — file-poll, tail -F-style read of
  <working-dir>/orchestrator-runlog.json (NDJSON). Maintains an in-memory
  map of pending submit events keyed by user_pubkey; on each applied /
  deprovision_applied event pairs the duration and appends it to a bounded
  ring used to compute provision / deprovision p95 over the active batch
  window.
• Heartbeat watcher — checks mtime of a ledger-heartbeat file the
  orchestrator updates (preferred over duplicating RPC config, as the issue
  recommends).
• Abort decider — consumes signals from the above, evaluates the trigger
  list, writes <working-dir>/abort exactly once with a JSON body
  {reason, t_ns, trigger} and sets a sticky internal flag so further signals
  are no-ops.

All file writes go to --working-dir. NDJSON is used for the append-mostly
structured outputs because it survives crash/SIGINT cleanly and is trivial to
validate. The show logging * per-sample files are plain text (eAPI returns
plain text for those).

Output formats

• Sample files:
  • JSON commands: one file per command per sample interval, named
    <command-slug>-<iso8601>.json. Slugs: show-hardware-capacity,
    show-gre-tunnel-static, show-processes-top. Body is the raw eAPI
    response.
  • Text commands: show-logging-errors-<iso8601>.log,
    show-logging-critical-<iso8601>.log. Body is the raw eAPI text output
    verbatim, no wrapping.
• observer.agent_metrics.json (NDJSON):
  {"t_ns": ..., "metric_name": "...", "value": ..., "labels_json": "{...}"}.
• observer.logging.json (NDJSON):
  {"t_ns": ..., "severity": "...", "facility": "...", "message": "..."}.
• observer-config.json (one-shot): full CLI options snapshot, written at
  startup for reproducibility (mirrors orchestrator-config.json).
• abort sentinel: written once on first trigger, body
  {"t_ns": ..., "trigger": "<key>", "reason": "<human-readable>"}.

CPU trigger — exact field path

Confirmed against the operator-supplied sample:

"cpuInfo": {
  "%Cpu(s)": {
    "user": 1.1, "system": 0.8, "nice": 0.0,
    "idle": 97.3, "ioWait": 0.0,
    "hwIrq": 0.4, "swIrq": 0.4, "stolen": 0.0
  }
}

Compute cpu_total = 100 - idle per sample. Maintain a ring keyed by t_ns
covering at least 60 s. Trigger when every sample in the trailing 60 s has
cpu_total > 80%. (Equivalent: trigger when min over the trailing-60 s window

80%.)

Key design choices and why

• Use github.com/aristanetworks/goeapi — already a dependency
  (go.mod), already used by e2e/internal/devnet/device.go to talk to cEOS,
  supports HTTP/HTTPS basic-auth eAPI directly. Avoids reimplementing
  JSON-RPC ourselves.
• Don't depend on the agent's gRPC eAPI proxy (aristapb.EapiMgrService).
  That requires the agent to be up — but the whole point of the observer is to
  watch the agent. Direct eAPI is independent.
• Tail orchestrator output files via file polling, not pipe. Both
  orchestrator.agent.log and orchestrator-runlog.json are tailed by the
  same small in-process tailer (open + seek-to-end + periodic poll + handle
  truncation/recreate by checking inode/size). The observer must work even if
  it's started after the orchestrator and must tolerate rotation. Implemented
  once, reused twice.
• Reuse the existing MetricsClient pattern but inline a smaller version
  under tools/stress/device-observer/ (the e2e helper isn't easily
  importable and carries unnecessary dependencies).
• Ledger heartbeat over direct RPC probe — the issue recommends the
  heartbeat approach; orchestrator already has the RPC config, observer
  should not duplicate it. Contract: orchestrator writes
  <working-dir>/ledger.heartbeat with the current time on every successful
  RPC call; observer watches its mtime and triggers if older than 30 s. The
  orchestrator side of this contract is its own work (stress: implement tools/stress/device-orchestrator #3746) — the observer
  should still function (without the ledger trigger) if the file is absent,
  with a "grace period until first heartbeat" rule so it never trips on
  cold-start.
• Runlog tail with in-memory pending-submit map — orchestrator emits rows
  in order: a submit row first, then a later applied row with the same
  user_pubkey. As tail-style reads pull new lines:
  • submit → insert into pending[user_pubkey] = t_submit.
  • applied → t_applied - pending[user_pubkey] → append to provision-p95
    ring; delete from pending.
  • deprovision_submit / deprovision_applied → same pattern against a
    second map / ring.
    This avoids re-scanning the file on every tick and avoids re-parsing rows
    we've already seen. The decider re-evaluates p95 every sample tick against
    the current ring contents.
• Sentinel writes once — a sync.Once plus an os.OpenFile(..., O_CREATE|O_EXCL, ...) ensures the file is only written once even if
  multiple triggers fire in the same tick.

Module layout

The existing tools/twamp/ lives inside the root Go module
(github.com/malbeclabs/doublezero). Follow the same pattern; do not
create a separate Go module. Imports will be
github.com/malbeclabs/doublezero/tools/stress/device-observer/....

Files to Change

Sub-issue decomposition follows in the "Estimated Scope" section. The list
below is the union across all chunks.

New (code)

• tools/stress/device-observer/cmd/device-observer/main.go — CLI flags
  (--dut-host, --eapi-user, --eapi-pass, --agent-metrics-url,
  --sample-interval default 10s, --abort-file default
  <working-dir>/abort, --working-dir), signal handling, goroutine wiring,
  config snapshot writer.
• tools/stress/device-observer/internal/eapi/client.go — thin wrapper around
  goeapi.Connect exposing RunShowJSON(cmd) ([]byte, error) and
  RunShowText(cmd) (string, error).
• tools/stress/device-observer/internal/sample/eos.go — sample loop;
  per-tick runs the five show ... commands, writes
  <command-slug>-<iso8601>.{json,log} files into --working-dir. Also
  surfaces the parsed CPU-total value to the abort decider via a small
  channel/accessor (avoid double-fetching the same response).
• tools/stress/device-observer/internal/tailer/tailer.go — generic
  file-poll tailer used by both the agent-log and the runlog readers
  (open + offset + recreate/truncate detection + partial-line buffer).
• tools/stress/device-observer/internal/promscrape/scrape.go — fetches
  --agent-metrics-url, parses with expfmt.NewTextParser, appends NDJSON
  rows to observer.agent_metrics.json. Surfaces last counter values to the
  abort decider via a small Snapshot() accessor.
• tools/stress/device-observer/internal/loggingtail/eos.go — show logging last <window> poller, splits + parses standard EOS syslog format
  (timestamp, severity, facility, message), filters out config-commit noise
  (%SYS-5-CONFIG_E, %SYS-5-CONFIG_I), dedupes, writes NDJSON rows.
• tools/stress/device-observer/internal/loggingtail/agent.go — uses
  tailer.Tailer against <working-dir>/orchestrator.agent.log; emits typed
  events (AgentLineSeen, CliTimeout, LockRaceObserved).
• tools/stress/device-observer/internal/runlog/reader.go — uses
  tailer.Tailer against <working-dir>/orchestrator-runlog.json. Owns
  pending-submit maps and bounded duration rings. Exposes
  ProvisionDurations(window), DeprovisionDurations(window), and
  per-event channels the decider can subscribe to.
• tools/stress/device-observer/internal/abort/decider.go — central
  state-machine: takes signals from all collectors, holds the rolling
  windows (60 s CPU ring, agent-silence timer, ledger-heartbeat watcher),
  computes p95 helpers, writes the sentinel file once with reason.

New (tests)

• tools/stress/device-observer/internal/eapi/client_test.go
• tools/stress/device-observer/internal/sample/eos_test.go — fixture eAPI
  response → expected files; covers both JSON and .log output paths and
  asserts CPU-total computation from operator's sample.
• tools/stress/device-observer/internal/tailer/tailer_test.go — covers
  append, partial trailing line, truncation, recreate.
• tools/stress/device-observer/internal/promscrape/scrape_test.go — fixture
  exposition format → expected NDJSON rows + counter snapshot.
• tools/stress/device-observer/internal/loggingtail/eos_test.go — fixture
  show logging output → expected rows.
• tools/stress/device-observer/internal/loggingtail/agent_test.go — fixture
  agent log appended in chunks → expected matches.
• tools/stress/device-observer/internal/runlog/reader_test.go — fixture
  NDJSON appended in chunks → expected paired durations; out-of-order
  applied before submit ignored gracefully.
• tools/stress/device-observer/internal/abort/decider_test.go — one test
  per abort trigger, each with a fixture:
  • provision p95 > 30s
  • provision single user > 30s
  • deprovision p95 > 30s
  • CPU sustained > 80% for 60s (using operator's sample shape)
  • apply_config_errors increment
  • get_config_errors increment
  • agent log Cli timeout
  • agent log lock race
  • agent silent > 15s
  • ledger heartbeat stale > 30s (with grace-period rule)

New (docs)

• tools/stress/device-observer/README.md — flags, output files, abort
  triggers, contract with the orchestrator (abort sentinel,
  ledger.heartbeat, orchestrator-runlog.json, orchestrator.agent.log).
• docs/work-plan-3747.md — this file.

Modified

• CHANGELOG.md — one Unreleased bullet per merged sub-issue, under a new
  "Tools" section if one doesn't exist, otherwise extend.

No existing source files outside tools/stress/device-observer/ need to
change.

Risks & Considerations

• eAPI JSON shape drift across EOS versions. show hardware capacity | json and show gre tunnel static | json differ between cEOS variants and
  the physical 7130LBR / 7280CR3A targets. Mitigation: write the raw eAPI
  response to disk verbatim (per the issue) and only parse the specific
  field used by the CPU trigger, which is now known
  (cpuInfo["%Cpu(s)"].idle). All other fields are recorded for post-hoc
  analysis.
• show logging is not native JSON. Per operator feedback: store the
  raw text verbatim as .log files; do not wrap in JSON. The separately
  parsed syslog stream (observer.logging.json) is the structured view used
  by the decider.
• Tailer correctness. Both runlog and agent-log readers must handle:
  appends, partial trailing lines (no newline yet), file truncation (new run
  starts), file recreation (orchestrator restart), and the file not existing
  yet at startup. All four cases get a tailer-level unit test.
• Out-of-order runlog events. If the observer is started mid-run, the
  first applied it sees may have no matching submit in its in-memory
  map. Ignore those events for p95 purposes (don't synthesize a pair from
  partial data).
• Heartbeat file may not exist on startup. The observer should not
  trigger ledger unreachable until at least one heartbeat has been seen —
  otherwise starting the observer before the orchestrator would always trip
  the alarm. Use a "grace period until first heartbeat" rule.
• Sentinel idempotency. sync.Once + O_CREATE|O_EXCL ensures one
  write. If a stale abort file exists from a prior run, the observer
  should refuse to start (or require a --force flag) so we don't conflate
  runs.
• Sample-interval drift. Use time.Ticker, not time.Sleep, so slow
  eAPI calls don't cumulatively shift the schedule. If a tick fires while
  the previous sample is still running, skip the tick and log a warning.
• Provision-window definition — confirmed by operator: window =
  [t_now - 2*hold_seconds, t_now], clamped at the most recent batch
  boundary. Documented in README.
• No new external deps. Everything needed (goeapi, expfmt,
  prometheus/common, slog) is already in go.mod.

Testing Strategy

• Unit tests — one per abort trigger (see file list). Each test
  constructs the decider with fixture inputs and asserts the sentinel
  is / isn't written, with the expected reason string.
• Tailer tests — append, partial line, truncation, recreate; reused
  by agent-log and runlog readers.
• Sampler integration check (manual + scripted) — point the binary at
  dz-local-device-dz1 (admin/admin eAPI) for 30 s and assert the five
  expected file kinds appear and parse (JSON files parse as JSON; .log
  files are non-empty text). The first sub-issue's PR description includes
  the exact docker exec/go run invocation.
• Prom scrape integration check — point at the running cEOS dz1's
  agent metrics endpoint (devnet exposes one) and assert
  observer.agent_metrics.json has rows for the documented metric names.
• Abort-trigger manual (per acceptance criterion): inject a fake
  show processes top once fixture with idle: 5.0, run a 90 s window,
  confirm abort appears within one sample interval after the 60 s
  threshold.
• No e2e test in this issue — the device-stress e2e is tracked
  separately (e2e: add device_stress_physical_test.go #3726 in the parent tracker). Unit-test coverage of each
  trigger is the acceptance contract.

Estimated Scope

Total new code (excluding tests/docs): ~700–900 lines. Substantially
over the 250-line per-PR threshold. Recommend splitting into the
following sub-issues, each independently mergeable and reviewable.

Sub-issue	Title	Est. code LOC	Outputs
3747-1	stress/device-observer: scaffolding + eAPI device sampler	~200	Binary builds; running it produces the five per-sample files (.json for JSON commands, .log for show logging *).
3747-2	stress/device-observer: agent Prometheus scrape	~150	observer.agent_metrics.json populates correctly; counter snapshot accessible internally.
3747-3	stress/device-observer: EOS syslog + tail-based readers (agent log, runlog)	~250	observer.logging.json populated; agent-log matchers emit typed events; runlog reader emits paired durations. Includes the shared tailer package.
3747-4	stress/device-observer: abort decider + sentinel	~200	<working-dir>/abort sentinel written on first matching trigger; one unit test per trigger.

Each chunk leaves the binary in a working, runnable state with the
previously shipped behavior intact. Chunk 1 ships the skeleton (with
no-op stubs where later chunks plug in); chunks 2–4 fill in real
implementations behind those stubs.

Operator decision needed

Per Roadbike change-size policy, please confirm:

1. Should I file the four sub-issues now (3747-1 … 3747-4), and what
   metadata (milestone, labels, assignees) should they carry? The
   parent [TRACKER] GRE Tunnel Capacity Study #3744 carries milestone "Device Stress Test" and no labels;
   sibling stress: implement tools/stress/device-orchestrator #3746 is assigned to @elitegreg. Default proposal: same
   milestone, no labels, assignee @nikw9944, link each as a child of
   stress: implement tools/stress/device-observer #3747.
2. Implementation order — proposed: 1 → 2 → 3 → 4 (each builds on the
   previous), but 2 and 3 are independent of each other after 1 lands and
   could go in either order or in parallel.
3. Should stress: implement tools/stress/device-observer #3747 itself be re-scoped to the scaffolding chunk (and the
   other three filed as separate issues), or kept as the umbrella and
   closed only when all four land?

Open Questions

(All previous open questions resolved by operator feedback in this
revision. None outstanding.)

[nikw9944]

Work Log — waiting_review

STATUS: COMPLETE — Revised plan saved to docs/work-plan-3747.md.

---

Work Plan — Issue #3747 (Revision 2)

stress: implement tools/stress/device-observer

Tracker: #3744 — GRE Tunnel Capacity Study

Revision Notes

Revision 2 incorporates operator decisions on revision 1:

• Sub-issues will be filed as 3747-1 … 3747-4 with same milestone/project as stress: implement tools/stress/device-observer #3747, no labels, assignee @nikw9944, each linked as a child of stress: implement tools/stress/device-observer #3747.
• Implementation order confirmed: 1 → 2 → 3 → 4.
• PR strategy: stacked PRs. PR 1 targets main; PR 2 targets PR 1's branch; PR 3 targets PR 2's branch; PR 4 targets PR 3's branch. Each PR stays at or under doublezero's recommended size. After PR 1 merges to main, PR 2 is rebased onto main; same cascade for 3 and 4. This keeps each PR independently reviewable but allows the full feature to be built up before any of it lands.
• stress: implement tools/stress/device-observer #3747 remains the umbrella issue and closes only when all four sub-issues are closed.

Revision 1 (preserved for context) addressed earlier operator feedback:

• CPU trigger field path: show processes top once | json exposes total CPU as cpuInfo["%Cpu(s)"].idle (a percentage). Total = 100 - idle.
• show hardware capacity / show gre tunnel static: raw eAPI response stored verbatim. No parsing of specific fields needed.
• show logging outputs are plain text: stored as show-logging-errors-<iso8601>.log / show-logging-critical-<iso8601>.log. Structured syslog view remains NDJSON.
• Runlog reader is tail-style, mirroring the agent-log tailer; decider keeps an in-memory rolling pending-submit map keyed by user_pubkey.
• Batch-window default confirmed: [t_now - 2*hold_seconds, t_now], clamped at the last batch boundary.
• --abort-file default confirmed: <working-dir>/abort.

Summary

Build a standalone Go binary at tools/stress/device-observer/ that runs alongside the (separate) device-orchestrator during a GRE-tunnel-capacity sweep on an isolated Arista DUT. The observer is an independent sampler: it polls the DUT over eAPI, scrapes the agent's Prometheus metrics, tails EOS syslog and the orchestrator's captured agent log, and — on the first sign of a defined fault — writes a sentinel file (<working-dir>/abort) that the orchestrator polls to halt the sweep. Splitting this from the orchestrator keeps the breaking-point detection logic out of the sweep path and lets either side be replaced/restarted independently.

Approach

Top-level shape

A single cmd/device-observer/main.go parses flags, opens the eAPI client and metrics scraper, opens output writers, and starts a small set of goroutines that share a context.Context and a single "abort decider" channel:

• eAPI sampler — every --sample-interval runs the five show ... commands and writes one file per sample. JSON commands → <command>-<iso8601>.json. Text show logging {errors,critical} → <command>-<iso8601>.log.
• Metrics scraper — every --sample-interval GETs --agent-metrics-url, parses with prometheus/common/expfmt, appends one row per metric+labels combo to observer.agent_metrics.json (NDJSON).
• EOS log tail — every --sample-interval runs show logging last <window>, parses each non-config-commit line, dedupes against a moving window, appends rows to observer.logging.json (NDJSON).
• Agent-log tail — file-poll, tail -F-style read of <working-dir>/orchestrator.agent.log, emitting matches for the two trigger strings + tracking time-since-last-line for the agent-silence trigger.
• Run-log tail — file-poll, tail -F-style read of <working-dir>/orchestrator-runlog.json (NDJSON). Maintains an in-memory map of pending submit events keyed by user_pubkey; on each applied / deprovision_applied event pairs the duration and appends it to a bounded ring used to compute provision / deprovision p95 over the active batch window.
• Heartbeat watcher — checks mtime of a ledger-heartbeat file the orchestrator updates (preferred over duplicating RPC config, as the issue recommends).
• Abort decider — consumes signals from the above, evaluates the trigger list, writes <working-dir>/abort exactly once with a JSON body {reason, t_ns, trigger} and sets a sticky internal flag so further signals are no-ops.

All file writes go to --working-dir. NDJSON is used for the append-mostly structured outputs because it survives crash/SIGINT cleanly and is trivial to validate. The show logging * per-sample files are plain text (eAPI returns plain text for those).

Output formats

• Sample files:
  • JSON commands: one file per command per sample interval, named <command-slug>-<iso8601>.json. Slugs: show-hardware-capacity, show-gre-tunnel-static, show-processes-top. Body is the raw eAPI response.
  • Text commands: show-logging-errors-<iso8601>.log, show-logging-critical-<iso8601>.log. Body is the raw eAPI text output verbatim, no wrapping.
• observer.agent_metrics.json (NDJSON): {"t_ns": ..., "metric_name": "...", "value": ..., "labels_json": "{...}"}.
• observer.logging.json (NDJSON): {"t_ns": ..., "severity": "...", "facility": "...", "message": "..."}.
• observer-config.json (one-shot): full CLI options snapshot, written at startup for reproducibility (mirrors orchestrator-config.json).
• abort sentinel: written once on first trigger, body {"t_ns": ..., "trigger": "<key>", "reason": "<human-readable>"}.

CPU trigger — exact field path

Confirmed against the operator-supplied sample:

"cpuInfo": {
  "%Cpu(s)": {
    "user": 1.1, "system": 0.8, "nice": 0.0,
    "idle": 97.3, "ioWait": 0.0,
    "hwIrq": 0.4, "swIrq": 0.4, "stolen": 0.0
  }
}

Compute cpu_total = 100 - idle per sample. Maintain a ring keyed by t_ns covering at least 60 s. Trigger when every sample in the trailing 60 s has cpu_total > 80%. (Equivalent: trigger when min over the trailing-60 s window > 80%.)

Key design choices and why

• Use github.com/aristanetworks/goeapi — already a dependency (go.mod), already used by e2e/internal/devnet/device.go to talk to cEOS, supports HTTP/HTTPS basic-auth eAPI directly. Avoids reimplementing JSON-RPC ourselves.
• Don't depend on the agent's gRPC eAPI proxy (aristapb.EapiMgrService). That requires the agent to be up — but the whole point of the observer is to watch the agent. Direct eAPI is independent.
• Tail orchestrator output files via file polling, not pipe. Both orchestrator.agent.log and orchestrator-runlog.json are tailed by the same small in-process tailer (open + seek-to-end + periodic poll + handle truncation/recreate by checking inode/size). The observer must work even if it's started after the orchestrator and must tolerate rotation. Implemented once, reused twice.
• Reuse the existing MetricsClient pattern but inline a smaller version under tools/stress/device-observer/ (the e2e helper isn't easily importable and carries unnecessary dependencies).
• Ledger heartbeat over direct RPC probe — the issue recommends the heartbeat approach; orchestrator already has the RPC config, observer should not duplicate it. Contract: orchestrator writes <working-dir>/ledger.heartbeat with the current time on every successful RPC call; observer watches its mtime and triggers if older than 30 s. The orchestrator side of this contract is its own work (stress: implement tools/stress/device-orchestrator #3746) — the observer should still function (without the ledger trigger) if the file is absent, with a "grace period until first heartbeat" rule so it never trips on cold-start.
• Runlog tail with in-memory pending-submit map — orchestrator emits rows in order: a submit row first, then a later applied row with the same user_pubkey. As tail-style reads pull new lines:
  • submit → insert into pending[user_pubkey] = t_submit.
  • applied → t_applied - pending[user_pubkey] → append to provision-p95 ring; delete from pending.
  • deprovision_submit / deprovision_applied → same pattern against a second map / ring.
    This avoids re-scanning the file on every tick and avoids re-parsing rows we've already seen. The decider re-evaluates p95 every sample tick against the current ring contents.
• Sentinel writes once — a sync.Once plus an os.OpenFile(..., O_CREATE|O_EXCL, ...) ensures the file is only written once even if multiple triggers fire in the same tick.

Module layout

The existing tools/twamp/ lives inside the root Go module (github.com/malbeclabs/doublezero). Follow the same pattern; do not create a separate Go module. Imports will be github.com/malbeclabs/doublezero/tools/stress/device-observer/....

Sub-issues and Stacked-PR Plan

Per operator direction, the work ships as four stacked PRs, each backed by a child issue of #3747. Each sub-issue gets the same milestone and project as #3747, no labels, and assignee @nikw9944.

Sub-issue list (to file)

#	Title	Branch	PR base
3747-1	stress/device-observer: scaffolding + eAPI device sampler	nikw9944/doublezero-3747-1	main
3747-2	stress/device-observer: agent Prometheus scrape	nikw9944/doublezero-3747-2	nikw9944/doublezero-3747-1
3747-3	stress/device-observer: EOS syslog + tail-based readers	nikw9944/doublezero-3747-3	nikw9944/doublezero-3747-2
3747-4	stress/device-observer: abort decider + sentinel	nikw9944/doublezero-3747-4	nikw9944/doublezero-3747-3

After PR 1 merges to main, PR 2's base is switched to main (GitHub auto-retargets if PR 1's branch is deleted on merge; otherwise switch manually) and the branch is rebased onto main + force-pushed. The same cascade applies for PR 3 and PR 4.

Per-sub-issue scope

3747-1 — scaffolding + eAPI device sampler (~200 LOC code)

• Creates tools/stress/device-observer/cmd/device-observer/main.go with flag parsing, signal handling, working-dir creation, observer-config.json one-shot writer.
• Creates internal/eapi/client.go (wrapper around goeapi.Connect, RunShowJSON + RunShowText).
• Creates internal/sample/eos.go (per-tick loop running the five show commands, writing JSON files for the three JSON commands and .log files for the two show logging commands).
• Stubs the other collectors as no-op interfaces so the goroutine wiring exists from PR 1.
• Adds tools/stress/device-observer/README.md (initial draft documenting the binary, flags, and output file layout).
• Lands docs/work-plan-3747.md (this file).
• Output: binary builds and produces the five per-sample files when pointed at dz-local-device-dz1.

3747-2 — agent Prometheus scrape (~150 LOC code)

• Creates internal/promscrape/scrape.go (fetches --agent-metrics-url, parses with expfmt.NewTextParser, appends to observer.agent_metrics.json).
• Surfaces a Snapshot() accessor with the latest counter values for the abort decider (decider lands in PR 4 — for now it's just exposed).
• Wires the scraper into main.go as a real goroutine replacing the PR 1 stub.
• Updates README with the metrics-output section.

3747-3 — EOS syslog + tail-based readers (~250 LOC code)

• Creates internal/tailer/tailer.go (shared poll-based tailer with open + offset + recreate/truncate detection + partial-line buffering).
• Creates internal/loggingtail/eos.go (show logging last <window> poller with parse + dedupe + NDJSON output).
• Creates internal/loggingtail/agent.go (uses tailer.Tailer against <working-dir>/orchestrator.agent.log; emits typed events).
• Creates internal/runlog/reader.go (uses tailer.Tailer against <working-dir>/orchestrator-runlog.json; owns pending-submit maps and bounded duration rings; exposes ProvisionDurations(window) and DeprovisionDurations(window)).
• Updates README with EOS-log / agent-log / runlog sections.

3747-4 — abort decider + sentinel (~200 LOC code)

• Creates internal/abort/decider.go (central state machine, rolling windows, p95 helpers, sentinel writer).
• Wires all collector outputs into the decider (replacing PR 1 stub channels).
• Adds startup check that refuses to start when a stale abort exists in --working-dir unless --force.
• Adds unit test per trigger (full list in "Files to Change → New (tests)" below).
• Updates README with abort-trigger table and operator-contract section.

Each chunk leaves the binary in a working, runnable state with the previously shipped behavior intact.

Files to Change

The list below is the union across all four sub-issues. See the per-sub-issue scope above for the chunk that each file lands in.

New (code)

• tools/stress/device-observer/cmd/device-observer/main.go — CLI flags (--dut-host, --eapi-user, --eapi-pass, --agent-metrics-url, --sample-interval default 10s, --abort-file default <working-dir>/abort, --working-dir), signal handling, goroutine wiring, config snapshot writer.
• tools/stress/device-observer/internal/eapi/client.go — thin wrapper around goeapi.Connect exposing RunShowJSON(cmd) ([]byte, error) and RunShowText(cmd) (string, error).
• tools/stress/device-observer/internal/sample/eos.go — sample loop; per-tick runs the five show ... commands, writes <command-slug>-<iso8601>.{json,log} files into --working-dir. Also surfaces the parsed CPU-total value to the abort decider via a small channel/accessor (avoid double-fetching the same response).
• tools/stress/device-observer/internal/tailer/tailer.go — generic file-poll tailer used by both the agent-log and the runlog readers (open + offset + recreate/truncate detection + partial-line buffer).
• tools/stress/device-observer/internal/promscrape/scrape.go — fetches --agent-metrics-url, parses with expfmt.NewTextParser, appends NDJSON rows to observer.agent_metrics.json. Surfaces last counter values to the abort decider via a small Snapshot() accessor.
• tools/stress/device-observer/internal/loggingtail/eos.go — show logging last <window> poller, splits + parses standard EOS syslog format (timestamp, severity, facility, message), filters out config-commit noise (%SYS-5-CONFIG_E, %SYS-5-CONFIG_I), dedupes, writes NDJSON rows.
• tools/stress/device-observer/internal/loggingtail/agent.go — uses tailer.Tailer against <working-dir>/orchestrator.agent.log; emits typed events (AgentLineSeen, CliTimeout, LockRaceObserved).
• tools/stress/device-observer/internal/runlog/reader.go — uses tailer.Tailer against <working-dir>/orchestrator-runlog.json. Owns pending-submit maps and bounded duration rings. Exposes ProvisionDurations(window), DeprovisionDurations(window), and per-event channels the decider can subscribe to.
• tools/stress/device-observer/internal/abort/decider.go — central state-machine: takes signals from all collectors, holds the rolling windows (60 s CPU ring, agent-silence timer, ledger-heartbeat watcher), computes p95 helpers, writes the sentinel file once with reason.

New (tests)

• tools/stress/device-observer/internal/eapi/client_test.go (PR 1)
• tools/stress/device-observer/internal/sample/eos_test.go — fixture eAPI response → expected files; covers both JSON and .log output paths and asserts CPU-total computation from operator's sample. (PR 1)
• tools/stress/device-observer/internal/tailer/tailer_test.go — covers append, partial trailing line, truncation, recreate. (PR 3)
• tools/stress/device-observer/internal/promscrape/scrape_test.go — fixture exposition format → expected NDJSON rows + counter snapshot. (PR 2)
• tools/stress/device-observer/internal/loggingtail/eos_test.go — fixture show logging output → expected rows. (PR 3)
• tools/stress/device-observer/internal/loggingtail/agent_test.go — fixture agent log appended in chunks → expected matches. (PR 3)
• tools/stress/device-observer/internal/runlog/reader_test.go — fixture NDJSON appended in chunks → expected paired durations; out-of-order applied before submit ignored gracefully. (PR 3)
• tools/stress/device-observer/internal/abort/decider_test.go — one test per abort trigger, each with a fixture (PR 4):
  • provision p95 > 30s
  • provision single user > 30s
  • deprovision p95 > 30s
  • CPU sustained > 80% for 60s (using operator's sample shape)
  • apply_config_errors increment
  • get_config_errors increment
  • agent log Cli timeout
  • agent log lock race
  • agent silent > 15s
  • ledger heartbeat stale > 30s (with grace-period rule)

New (docs)

• tools/stress/device-observer/README.md — flags, output files, abort triggers, contract with the orchestrator (abort sentinel, ledger.heartbeat, orchestrator-runlog.json, orchestrator.agent.log). Drafted in PR 1; extended in each subsequent PR.
• docs/work-plan-3747.md — this file. (PR 1)

Modified

• CHANGELOG.md — one Unreleased bullet per merged sub-issue, under a new "Tools" section if one doesn't exist, otherwise extend.

No existing source files outside tools/stress/device-observer/ need to change.

Risks & Considerations

• eAPI JSON shape drift across EOS versions. show hardware capacity | json and show gre tunnel static | json differ between cEOS variants and the physical 7130LBR / 7280CR3A targets. Mitigation: write the raw eAPI response to disk verbatim (per the issue) and only parse the specific field used by the CPU trigger, which is now known (cpuInfo["%Cpu(s)"].idle). All other fields are recorded for post-hoc analysis.
• show logging is not native JSON. Per operator feedback: store the raw text verbatim as .log files; do not wrap in JSON. The separately parsed syslog stream (observer.logging.json) is the structured view used by the decider.
• Tailer correctness. Both runlog and agent-log readers must handle: appends, partial trailing lines (no newline yet), file truncation (new run starts), file recreation (orchestrator restart), and the file not existing yet at startup. All four cases get a tailer-level unit test.
• Out-of-order runlog events. If the observer is started mid-run, the first applied it sees may have no matching submit in its in-memory map. Ignore those events for p95 purposes (don't synthesize a pair from partial data).
• Heartbeat file may not exist on startup. The observer should not trigger ledger unreachable until at least one heartbeat has been seen — otherwise starting the observer before the orchestrator would always trip the alarm. Use a "grace period until first heartbeat" rule.
• Sentinel idempotency. sync.Once + O_CREATE|O_EXCL ensures one write. If a stale abort file exists from a prior run, the observer should refuse to start (or require a --force flag) so we don't conflate runs.
• Sample-interval drift. Use time.Ticker, not time.Sleep, so slow eAPI calls don't cumulatively shift the schedule. If a tick fires while the previous sample is still running, skip the tick and log a warning.
• Provision-window definition — confirmed by operator: window = [t_now - 2*hold_seconds, t_now], clamped at the most recent batch boundary. Documented in README.
• Stacked-PR rebase friction. When PR 1 merges, PR 2 needs its base switched to main and a rebase; same cascade for 3→4. GitHub auto-updates the base when the source branch is deleted, but rebases happen manually. Plan: rebase each follow-up branch onto main immediately after the prior PR merges, then force-push.
• No new external deps. Everything needed (goeapi, expfmt, prometheus/common, slog) is already in go.mod.

Testing Strategy

• Unit tests — one per abort trigger (see file list). Each test constructs the decider with fixture inputs and asserts the sentinel is / isn't written, with the expected reason string.
• Tailer tests — append, partial line, truncation, recreate; reused by agent-log and runlog readers.
• Sampler integration check (manual + scripted) — point the binary at dz-local-device-dz1 (admin/admin eAPI) for 30 s and assert the five expected file kinds appear and parse (JSON files parse as JSON; .log files are non-empty text). PR 1's description includes the exact docker exec/go run invocation.
• Prom scrape integration check — point at the running cEOS dz1's agent metrics endpoint (devnet exposes one) and assert observer.agent_metrics.json has rows for the documented metric names.
• Abort-trigger manual (per acceptance criterion): inject a fake show processes top once fixture with idle: 5.0, run a 90 s window, confirm abort appears within one sample interval after the 60 s threshold.
• No e2e test in this issue — the device-stress e2e is tracked separately (e2e: add device_stress_physical_test.go #3726 in the parent tracker). Unit-test coverage of each trigger is the acceptance contract.

Estimated Scope

Total new code (excluding tests/docs): ~700–900 lines, split across four stacked PRs as detailed in the "Sub-issues and Stacked-PR Plan" section. Each individual PR stays at or under doublezero's recommended size threshold (most stay well under, ~150–250 LOC).

Open Questions

All previous open questions resolved by operator feedback. None outstanding.

--- Result: success | Session cost: $1.0246 | Turns: 5 | Tokens: 10 in / 27051 out | 2026-05-22 20:28:22 UTC ---