azure_logs_ingestion plugin causes Fluent Bit to segfault during --dry-run

[phaest]

Bug Report

Using the azure_logs_ingestion output plugin causes Fluent Bit to crash with a segmentation fault when running with --dry-run.

This reproduces with the latest Fluent Bit container image and a minimal configuration. If the azure_logs_ingestion output is removed from the config, --dry-run completes successfully.

To Reproduce

• Save the azure_logs_ingestion documentation example config as a file with name: fluent_bit.yaml. Content taken from the documentation page (azure_logs_ingestion docs):

pipeline:
  inputs:
    - name: tail
      path: /path/to/your/sample.log
      tag: sample
      key: RawData

    # Or use other plugins
    #- name: cpu
    #  tag: sample

  filters:
    - name: modify
      match: sample
      # Add a json key named "Application":"fb_log"
      add: Application fb_log

  outputs:
    # Enable this section to see your json-log format
    #- name: stdout
    #  match: '*'

    - name: azure_logs_ingestion
      match: sample
      client_id: XXXXXXXX-xxxx-yyyy-zzzz-xxxxyyyyzzzzxyzz
      client_secret: some.secret.xxxzzz
      tenant_id: XXXXXXXX-xxxx-yyyy-zzzz-xxxxyyyyzzzzxyzz
      dce_url: https://log-analytics-dce-XXXX.region-code.ingest.monitor.azure.com
      dcr_id: dcr-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
      table_name: ladcr_CL
      time_generated: true
      time_key: Time
      compress: true

• Run the container with --dry-run command:
  docker run -ti -v ./fluent-bit.yaml:/fluent-bit/etc/fluent-bit.yaml \ cr.fluentbit.io/fluent/fluent-bit \ -c /fluent-bit/etc/fluent-bit.yaml

• Result of the run command:
  Fluent Bit crashes with SIGSEGV, with the trace pointing to output shutdown:

PS C:\Source> docker run -ti -v ./fluent-bit.yaml:/fluent-bit/etc/fluent-bit.yaml cr.fluentbit.io/fluent/fluent-bit -c /fluent-bit/etc/fluent-bit.yaml --dry-run
Fluent Bit v5.0.5
* Copyright (C) 2015-2026 The Fluent Bit Authors
* Fluent Bit is a CNCF graduated project under the Fluent organization
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |  ___||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   _|___ \ | |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \|  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V //\__/ /\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)\___/


[2026/05/08 09:09:53] [engine] caught signal (SIGSEGV)
#0  0x647f64480f54      in  flb_output_exit() at src/flb_output.c:587
#1  0x647f64495b84      in  flb_engine_shutdown() at src/flb_engine.c:1356
#2  0x647f64463ae4      in  flb_destroy() at src/flb_lib.c:246
#3  0x647f643cf758      in  flb_main_run() at src/fluent-bit.c:1445
#4  0x7b988a730ca7      in  ???() at ???:0
#5  0x7b988a730d64      in  ???() at ???:0
#6  0x647f643cd170      in  ???() at ???:0
#7  0xffffffffffffffff  in  ???() at ???:0

Expected behavior
--dry-run should validate the configuration and exit cleanly without crashing.

Screenshots

Your Environment

• Version used: 3.1.7-5.0.5
• Configuration: Minimal example configuration from plugin docs page: (azure_logs_ingestion docs)
• Environment name and version: Tested with same result on Oracle Linux and Windows Docker Desktop with WSL 2
• Operating System and version: Oracle Linux, WSL 2
• Filters and plugins: azure_logs_ingestion

Additional context
The issue prevents me from validating configuration using --dry-run prior to release.

[patrick-stephens]

@edsiper / @cosmo0920 would this be causing the failures I am seeing with dry-run in fluent/fluent-bit-docs#2627 for various plugin examples.

The examples in the docs for the following pages all trigger a segv when run with dry-run:

• pipeline/outputs/azure_blob.md
• pipeline/outputs/nats.md
• pipeline/outputs/kafka-rest-proxy.md

EDIT: yes it looks like a similar root cause with missing NULL checks at exit, fixed by #12114.