"# DevOps Monitoring & Alerting Stack

A Docker-based monitoring and alerting solution using Prometheus, Grafana, Node Exporter, and AlertManager. This stack provides comprehensive system monitoring, visualization, and alert notifications via email.

• Overview
• Prerequisites
• Quick Start
• Services
• Access Points
• Configuration
• Architecture
• Alert Rules
• Usage
• Troubleshooting

This project sets up a complete monitoring ecosystem that:

• Collects system metrics from your infrastructure
• Stores and queries metrics using Prometheus
• Visualizes data through Grafana dashboards
• Triggers alerts based on predefined rules
• Sends notifications via email

Before starting, ensure you have:

• Docker (v20.10 or higher)
• Docker Compose (v1.29 or higher)
• A valid Gmail account (for email alerts)
• At least 2GB of RAM allocated to Docker

1. Clone or navigate to the project directory:

   cd d:\Devops

2. Update AlertManager configuration:

   • Edit alertmanager.yml and update Gmail credentials with an app-specific password

3. Start all services:

   docker-compose up -d

4. Verify services are running:

   docker-compose ps

5. Access the services:

   • Prometheus: http://localhost:9090
   • Grafana: http://localhost:3000
   • AlertManager: http://localhost:9093

• Port: 9090
• Purpose: Metrics collection and storage
• Configuration: prometheus.yml
• Scrape Interval: 5 seconds
• Features:
  • Collects metrics from Node Exporter
  • Evaluates alert rules
  • Routes alerts to AlertManager

• Port: 3000
• Purpose: Metrics visualization and dashboards
• Default Credentials:
  • Username: admin
  • Password: admin
• Features:
  • Create custom dashboards
  • Visualize Prometheus metrics
  • Alert management UI

• Port: 9100
• Purpose: Exports system and hardware metrics
• Metrics Exposed:
  • CPU usage
  • Memory usage
  • Disk I/O
  • Network statistics
  • Process information

• Port: 9093
• Purpose: Handles and routes alerts
• Configuration: alertmanager.yml
• Notification Method: Email

Global Settings:
- Scrape interval: 5 seconds
- Target: Node Exporter on port 9100

Alert Configuration:
- Rule file: alert.rules.yml
- AlertManager target: localhost:9093

Triggered alerts:

• HighCPUUsage: Triggers when CPU usage > 5% for 1 second
• HighMemoryUsage: Triggers when Memory usage > 5% for 1 second

Email notification settings:

• SMTP Server: smtp.gmail.com:587
• From Email: raghulpg2006@gmail.com
• To Email: raghulpg2006@gmail.com
• TLS: Enabled

Email Template:

• Uses custom HTML template (email_template.html) for professional alert formatting
• Features:
  • Color-coded alert status (🔴 Red for active, ✅ Green for resolved)
  • Severity badges with visual indicators
  • Clean, organized layout with instance details
  • Direct links to AlertManager for quick access
  • Professional styling with improved readability
  • Grouped alerts for better organization

┌─────────────────────────────────────────────────────────────────┐
│                        Monitoring Stack                         │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  ┌──────────────────┐  ┌──────────────────┐  ┌──────────────┐ │
│  │  Node Exporter   │  │   Prometheus     │  │    Grafana   │ │
│  │   (9100)         │  │    (9090)        │  │   (3000)     │ │
│  └────────┬─────────┘  └────────┬─────────┘  └──────┬───────┘ │
│           │                     │                    │          │
│           │    Metrics          │                    │          │
│           └─────────────────────┤                    │          │
│                                 │ Alert Rules        │          │
│                            ┌────▼─────────────┐     │          │
│                            │  Alert Manager   │     │          │
│                            │    (9093)        │     │          │
│                            └────┬─────────────┘     │          │
│                                 │                    │          │
│                        ┌────────▼────────┐           │          │
│                        │   Email Alert   │           │          │
│                        │  (Gmail SMTP)   │           │          │
│                        └─────────────────┘           │          │
│                                                      │          │
│                          Connected to Grafana ───────┘          │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

The system monitors two critical metrics:

• Condition: CPU usage > 5%
• Duration: 1 second
• Severity: Critical
• Action: Email notification

• Condition: Memory usage > 5%
• Duration: 1 second
• Severity: Critical
• Action: Email notification

Note: Alert thresholds can be adjusted in alert.rules.yml

1. Open http://localhost:9090
2. Go to "Graph" tab
3. Example queries:
   • node_cpu_seconds_total - CPU metrics
   • node_memory_MemTotal_bytes - Memory metrics

1. Open http://localhost:3000
2. Login with default credentials
3. Add Prometheus as data source
4. Create visualization panels
5. Save as dashboard

1. Open http://localhost:9093
2. View active alerts
3. Check alert history

# Start services
docker-compose up -d

# Stop services
docker-compose down

# View logs for all services
docker-compose logs -f

# View logs for specific service
docker-compose logs -f prometheus
docker-compose logs -f grafana
docker-compose logs -f node_exporter
docker-compose logs -f alertmanager

# Restart services
docker-compose restart

# Check service status
docker-compose ps

# Remove containers and volumes
docker-compose down -v

• docker-compose.yml - Service definitions and configurations
• prometheus.yml - Prometheus configuration
• alert.rules.yml - Alert rules and thresholds
• alertmanager.yml - AlertManager configuration and notification settings
• email_template.html - Custom HTML email template for professional alert formatting
• README.md - This file

# Check logs
docker-compose logs

# Verify Docker daemon is running
docker ps

• Ensure Node Exporter is running: http://localhost:9100/metrics
• Check Prometheus target status in UI: http://localhost:9090/targets

• Verify Gmail credentials in alertmanager.yml
• Ensure "Less secure app access" is enabled (or use app-specific password)
• Check AlertManager logs: docker-compose logs alertmanager

• Ensure services are running: docker-compose ps
• Check if ports are already in use
• Try recreating containers: docker-compose down && docker-compose up -d

• Alert thresholds (5%) are set very low for testing. Adjust in alert.rules.yml for production
• Gmail credentials are hardcoded. For production, use secrets management
• Default Grafana password should be changed on first login
• Regular backups recommended for Prometheus data

For issues or questions, check:

• Individual service logs: docker-compose logs <service-name>
• Service health pages at their respective ports
• Official documentation:
  • Prometheus
  • Grafana
  • AlertManager"