Add Prometheus installation guide for Linux

node_exporter.md

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+# Node Exporter Installation (Linux)
+
+This guide explains how to install and configure Prometheus Node Exporter as a systemd service.
+
+Node Exporter exposes Linux system metrics such as CPU, memory, disk, and network statistics so that Prometheus can scrape and store them.
+
+Default metrics endpoint:
+http://SERVER_IP:9100/metrics
+
+---
+
+## 1. Download Node Exporter
+
+```bash
+sudo wget <NODE_EXPORTER_DOWNLOAD_LINK>
+```
+Purpose
+
+Downloads the Node Exporter binary from GitHub releases.
+
+## 2. Extract Archive
+
+```bash
+sudo tar xzf node_exporter-*.tar.gz
+```
+
+Purpose
+
+Extracts the Node Exporter binary from the compressed archive.
+
+## 3. Test Node Exporter Manually
+
+```bash
+./node_exporter
+```
+
+Result
+
+Starts Node Exporter
+
+Exposes metrics on port 9100
+
+Verify:
+
+```bash
+http://SERVER_IP:9100/metrics
+```
+
+This step confirms the binary works before creating a service.
+
+## 4. Create Prometheus Service User (Security Best Practice)
+
+```bash
+sudo groupadd --system prometheus
+sudo useradd -s /sbin/nologin --system -g prometheus prometheus
+```
+
+Why
+
+Prevents running exporter as root
+
+Improves production security
+
+## 5. Create Installation Directory
+
+```bash
+sudo mkdir /var/lib/node
+```
+
+
+Purpose
+
+Stores Node Exporter binary in a dedicated location.
+
+## 6. Move Binary
+
+```bash
+sudo mv node_exporter /var/lib/node/
+```
+##7. Create Systemd Service
+
+```bash
+sudo nano /etc/systemd/system/node.service
+```
+
+```bash
+[Unit]
+Description=Prometheus Node Exporter
+Documentation=https://prometheus.io/docs/introduction/overview/
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+Type=simple
+User=prometheus
+Group=prometheus
+ExecReload=/bin/kill -HUP $MAINPID
+ExecStart=/var/lib/node/node_exporter
+
+SyslogIdentifier=prometheus_node_exporter
+Restart=always
+
+[Install]
+WantedBy=multi-user.target
+```
+
+Purpose
+
+Runs Node Exporter as a background service
+
+Enables restart on failure
+
+Allows automatic startup during boot
+
+
+## 8. Set Permissions
+
+```bash
+sudo chown -R prometheus:prometheus /var/lib/node
+sudo chmod -R 775 /var/lib/node/
+```
+
+Why
+
+Prevents permission-related service failures
+
+Allows Prometheus user to execute exporter
+
+## 9. Start and Enable Service
+
+```bash
+sudo systemctl daemon-reload
+sudo systemctl start node
+sudo systemctl enable node
+```
+
+## 10. Verify Service
+
+```bash
+sudo systemctl status node
+```
+
+Then open:
+
+```bash
+http://SERVER_IP:9100/metrics
+```
+
+What Node Exporter Provides
+
+CPU usage
+
+Memory usage
+
+Disk utilization
+
+Network statistics
+
+Filesystem metrics
+
+Load average
+
+## Connect Node Exporter to Prometheus
+
+Add this to prometheus.yml:
+
+```bash
+scrape_configs:
+  - job_name: "node_exporter"
+    static_configs:
+      - targets: ["SERVER_IP:9100"]
+```
+
+Then restart Prometheus:
+
+```bash
+sudo systemctl restart prometheus
+```
+
+
+⚠️ Common Mistakes
+
+Forgetting to open firewall port 9100
+
+Wrong binary path in systemd service
+
+Permission denied errors
+
+Not reloading systemd daemon

prometheus-setup.md

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+# Prometheus Installation on Linux
+
+This guide documents the step-by-step installation and configuration of Prometheus using a binary installation approach and running it as a systemd service.
+
+Prometheus is an open-source monitoring and alerting toolkit used to collect and store time-series metrics in DevOps and cloud environments.
+
+---
+
+## 1. Update System Packages
+
+```bash
+sudo apt-get update
+```
+
+Purpose
+
+Refreshes package lists
+
+Prevents dependency conflicts during installation
+
+---
+
+## 2. Download Prometheus
+
+```bash
+sudo wget https://github.com/prometheus/prometheus/releases/download/v3.10.0-rc.1/prometheus-3.10.0-rc.1.linux-amd64.tar.gz
+```
+
+Purpose
+
+Downloads the Prometheus precompiled binary
+
+## 3. Create Prometheus Service User (Security Best Practice)
+
+```bash
+sudo groupadd --system prometheus
+sudo useradd -s /sbin/nologin --system -g prometheus prometheus
+```
+
+Why
+
+Prevents Prometheus from running as root
+
+Improves system security
+
+## 4. Create Prometheus Directories
+
+```bash
+sudo mkdir /var/lib/prometheus
+sudo mkdir -p /etc/prometheus/rules
+sudo mkdir -p /etc/prometheus/rules.s
+sudo mkdir -p /etc/prometheus/files_sd
+```
+
+| Directory             | Purpose                      |
+| --------------------- | ---------------------------- |
+| `/var/lib/prometheus` | Metrics storage (TSDB)       |
+| `/etc/prometheus`     | Configuration files          |
+| `rules/`              | Alerting & recording rules   |
+| `files_sd/`           | File-based service discovery |
+
+
+## 5. Extract Archive
+
+```bash
+sudo tar xzf prometheus-3.10.0-rc.1.linux-amd64.tar.gz
+```
+## 6. Move Binaries to System Path
+
+```bash
+sudo mv prometheus promtool /usr/local/bin
+prometheus --version
+```
+
+Why
+
+Allows Prometheus to run globally
+
+promtool is used for config validation
+
+
+
+## 7. Move Configuration File
+
+```bash
+sudo mv prometheus.yml /etc/prometheus/prometheus.yml
+```
+
+## 8. Create Systemd Service
+
+```bash
+sudo tee /etc/systemd/system/prometheus.service<<EOF
+[Unit]
+Description=Prometheus
+Documentation=https://prometheus.io/docs/introduction/overview/
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+Type=simple
+User=prometheus
+Group=prometheus
+ExecReload=/bin/kill -HUP \$MAINPID
+ExecStart=/usr/local/bin/prometheus \
+  --config.file=/etc/prometheus/prometheus.yml \
+  --storage.tsdb.path=/var/lib/prometheus \
+  --web.console.templates=/etc/prometheus/consoles \
+  --web.console.libraries=/etc/prometheus/console_libraries \
+  --web.listen-address=0.0.0.0:9090
+
+SyslogIdentifier=prometheus
+Restart=always
+
+[Install]
+WantedBy=multi-user.target
+EOF
+```
+
+Purpose
+
+Runs Prometheus as a managed Linux service
+
+Enables restart on failure
+
+Starts automatically on boot
+
+
+## 9. Set Permissions
+
+```bash
+sudo chown -R prometheus:prometheus /etc/prometheus
+sudo chmod -R 755 /etc/prometheus
+sudo chown -R prometheus:prometheus /var/lib/prometheus/
+```
+
+Why
+
+Prevents permission errors
+
+Allows Prometheus to write metrics safely
+
+## 10. Start and Enable Service
+
+```bash
+sudo systemctl daemon-reload
+sudo systemctl start prometheus
+sudo systemctl enable prometheus
+```
+
+## 11. Verify Installation
+
+```bash
+sudo systemctl status prometheus
+```
+
+## 12. Open browser:
+
+```bash
+http://SERVER_IP:9090
+```