Docker Helper

Manage Docker containers, images, volumes, networks, and Docker Compose projects. Use when the user wants to: (1) List/start/stop/restart Docker containers, (2) View container logs and stats, (3) Build and manage Docker images, (4) Create and manage docker-compose.yml files, (5) Clean up unused Docker resources, (6) Debug container issues. Best for developers, DevOps engineers, and anyone running Docker on their server.

Simplify Docker container management, compose setup, and debugging through natural language commands.

When to Use

✅ USE this skill when:

• "Show me all running containers"
• "Start/stop/restart container [name]"
• "Show logs for [container]"
• "Check disk usage of Docker"
• "Prune unused containers/images"
• "Create a docker-compose.yml for [service]"
• "What's running on port 8080?"
• "Container [name] won't start, debug it"

❌ DON'T use this skill when:

• Need Kubernetes management → use a K8s skill
• Building complex multi-service orchestrations → consider Docker Swarm/K8s skills
• Production deployment with zero-downtime → use deployment-specific skills

Workflow

1. Container Management

When the user asks about containers, the agent runs:

# List all
docker ps -a
docker ps --format "table {{.Names}}\t{{.Status}}\t{{.Ports}}"

# Inspect specific
docker inspect [container] | jq '.[0].NetworkSettings.Ports'
docker stats [container] --no-stream

# Control
docker start/stop/restart [container]
docker rm -f [container]    (only with user confirmation)

2. Logs & Debugging

For debugging container issues:

# Standard logs
docker logs [container] --tail 50
docker logs [container] --tail 200 | grep -i error

# Resource issues
docker stats --no-stream

# Check why container exited
docker inspect [container] | jq '.[0].State'
docker logs [container] --tail 20 --timestamps

3. Image Management

# List images
docker images

# Build
docker build -t [name]:[tag] .

# Cleanup (with confirmation)
docker image prune -a -f

4. Docker Compose

When the user needs a compose file:

1. Ask what services they need (e.g., "nginx + postgres + redis")
2. Generate a docker-compose.yml with:
   • Appropriate image tags (avoid latest in production)
   • Volume mounts for persistence
   • Network configuration
   • Health checks where applicable
   • Environment variable stubs (.env file)
3. Show the user the generated file, offer to adjust

5. Resource Cleanup (WITH CONFIRMATION)

Always ask for confirmation before:

• docker system prune -a -f (removes ALL unused resources)
• docker volume prune -f (removes orphaned volumes with data)
• docker image rm without the -f flag first

Common Templates

Web App (Node/Python + Postgres):

services:
  app:
    build: .
    ports: ["${PORT}:${PORT}"]
    env_file: .env
    depends_on: [db]
  db:
    image: postgres:16-alpine
    volumes: ["pgdata:/var/lib/postgresql/data"]
    environment:
      POSTGRES_DB: ${DB_NAME}
      POSTGRES_PASSWORD: ${DB_PASS}
volumes: {pgdata:}

Nginx Reverse Proxy:

services:
  nginx:
    image: nginx:alpine
    ports: ["80:80", "443:443"]
    volumes: ["./nginx.conf:/etc/nginx/nginx.conf:ro", "./html:/usr/share/nginx/html:ro"]

Examples

User: "What containers are running?" Agent: Runs docker ps --format "table..." and shows a clean table

User: "My nginx container won't start" Agent: Checks logs + inspect, identifies the port conflict or config error

User: "Clean up Docker, it's using too much space" Agent: Runs docker system df, shows usage, asks what to prune

User: "Create a compose file for a Python app with Redis" Agent: Generates docker-compose.yml + .env.example, explains each part

Notes

• Always prefix destructive commands with confirmation
• Use docker compose (v2) over docker-compose (v1) when available
• Prefer alpine-based images for smaller footprint
• For security: never expose Docker socket without TLS