This service deploys Prometheus, an open-source system monitoring and alerting toolkit with a multi-dimensional data model and powerful query language.

Services

prometheus: The Prometheus server for scraping and storing time series data.

Environment Variables

Variable Name	Description	Default Value
PROMETHEUS_VERSION	Prometheus image version	`v3.5.0`
PROMETHEUS_PORT_OVERRIDE	Host port mapping (maps to Prometheus port 9090 in container)	`9090`
PROMETHEUS_RETENTION_TIME	How long to retain data	`15d`
PROMETHEUS_RETENTION_SIZE	Maximum storage size (empty = unlimited)	`""`
PROMETHEUS_EXTERNAL_URL	External URL for Prometheus (used for links and redirects)	`http://localhost:9090`

Please modify the .env file as needed for your use case.

Volumes

prometheus_data: A volume for storing Prometheus time series data.
prometheus.yml: Optional custom configuration file (mount to /etc/prometheus/prometheus.yml).
rules: Optional directory for alerting and recording rules (mount to /etc/prometheus/rules).

Default Configuration

The default Prometheus configuration includes:

Scraping itself for metrics
Global scrape interval of 15 seconds
Basic web console access

Configuration Files

Custom Prometheus Configuration

Mount a custom prometheus.yml file to /etc/prometheus/prometheus.yml:

volumes:
  - ./prometheus.yml:/etc/prometheus/prometheus.yml

Example prometheus.yml:

global:
  scrape_interval: 15s
  evaluation_interval: 15s

scrape_configs:
  - job_name: 'prometheus'
    static_configs:
      - targets: ['localhost:9090']
  
  - job_name: 'node_exporter'
    static_configs:
      - targets: ['node_exporter:9100']

Alert Rules

Mount rules directory to /etc/prometheus/rules:

volumes:
  - ./rules:/etc/prometheus/rules

Data Retention

Configure data retention using environment variables:

PROMETHEUS_RETENTION_TIME: Time-based retention (e.g., 30d, 1y)
PROMETHEUS_RETENTION_SIZE: Size-based retention (e.g., 10GB, 1TB)

API Access

Web UI: http://localhost:9090
API endpoint: http://localhost:9090/api/v1/
Admin API is enabled for configuration reloads

Security Notes

Consider restricting access to the admin API in production
Use authentication/authorization proxy for production deployments
Monitor resource usage as Prometheus can consume significant storage and memory

Common Use Cases

Monitoring Docker Containers

Add cAdvisor to monitor container metrics:

services:
  cadvisor:
    image: gcr.io/cadvisor/cadvisor:latest
    ports:
      - "8080:8080"
    volumes:
      - /:/rootfs:ro
      - /var/run:/var/run:ro
      - /sys:/sys:ro
      - /var/lib/docker/:/var/lib/docker:ro
      - /dev/disk/:/dev/disk:ro

Service Discovery

Use file-based service discovery or integrate with service discovery systems like Consul or Kubernetes.

License

Prometheus is licensed under the Apache 2.0 license.