Docker metrics in Prometheus

Export Docker container metrics (memory usage, limits, and reservations) to Prometheus.

Features

• Collcts memory metrics per container.
• Supports Docker Swarm, Rancher, and Compose labels for stack/service identification.
• Compatible with cgroups v1 and v2.
• Exposes /metrics endpoint for Prometheus scraping.

Usage

Running via Docker

You can run the exporter as a Docker container. Example:

services:
  prometheus-integration:
    image: <your-docker-username>/prometheus-integration:latest
    privileged: true
    environment:
      DOCKER_CLUSTER_CGROUP_VERSION: v2
    network_mode: host
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
      - /sys:/host:ro
    pid: host
    ports:
      - "9476:9476"

• The exporter reads container cgroups from /host/sys.
• If you use cgroups v2, use DOCKER_CLUSTER_CGROUP_VERSION=v2.
• The /var/run/docker.sock volume allows the exporter to request Docker container info.

Running Locally

1. Build binary with Go 1.21:

go build -o prometheus-integration main.go

2. Run exporter:

./prometheus-integration

3. Metrics are available at http://localhost:9476/metrics.

Running via Docker Compose

version: '3.9'
services:
  prometheus-integration:
    build: .
    container_name: prometheus-docker-integration
    privileged: true
    pid: host
    network_mode: host
    environment:
      DOCKER_CLUSTER_CGROUP_VERSION: v2
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
      - /sys:/host:ro
    ports:
      - "9476:9476"
    restart: unless-stopped

Metrics

Metric	Description
docker_container_memory_usage_bytes	Memory usage of container in bytes (excluding cache)
docker_container_memory_reservation_bytes	Memory reserved for container
docker_container_memory_limit_bytes	Memory limit for container

Env Variables

• DOCKER_CLUSTER_CGROUP_VERSION – Optional, v1 (default) or v2.