docker

name	docker
description	Production-grade Docker configurations (Dockerfile, Compose, best practices)
argument-hint	<dockerization request>
level	2

Docker Skill

Use this skill when user explicitly requests Docker configurations.

When to Use

• User says: "dockerize", "add docker", "create a Dockerfile", "docker-compose"
• User wants to containerize an application
• User asks about Docker best practices

Trigger: docker: prefix or explicit Docker request

What This Skill Provides

Based on Docker Official Best Practices.

Files to Create

File	When
Dockerfile	Application containerization
.dockerignore	Exclude unnecessary files
docker-compose.yml	Multi-container orchestration
docker-compose.override.yml	Dev-specific overrides
compose.yaml	Compose v2 format

Common Deliverables

1. Multi-stage Dockerfile with build/production stages
2. .dockerignore to reduce image size
3. docker-compose.yml with:
   • Health checks
   • Resource limits
   • Named volumes
   • Networks
   • Secrets (for sensitive data)
4. Security best practices:
   • Non-root user
   • Minimal base images
   • No secrets in image

Steps

1. Analyze Requirements

   • Language/runtime of the application
   • Dependencies and ports
   • Environment variables needed
   • Persistent data requirements
   • Health check endpoint available?

2. Create Dockerfile

   • Choose appropriate base image
   • Multi-stage build pattern
   • Non-root user
   • Healthcheck directive
   • Labels for metadata

3. Create .dockerignore

   • Dependencies (node_modules, etc.)
   • Build outputs
   • Git and IDE files
   • Environment files

4. Create docker-compose.yml

   • Service definitions
   • Volume mounts
   • Network configuration
   • Resource limits
   • Health checks

5. Verify

   • docker build succeeds
   • docker compose up works
   • Health checks pass
   • No security warnings

Examples

User: "dockerize this Node.js API" Why good: Clear request with specific tech stack User: "add Docker support for the frontend app" Why good: Explicit Docker request User: "fix the login bug" Why bad: No Docker involved User: "build me a web app" (without Docker mention) Why bad: Docker not explicitly requested

Related Skills

Skill	Use When
@deploy-engineer	Full deployment with Docker
@infra-planner	Infrastructure design
@dep-auditor	Check for vulnerabilities

Documentation

See skills/docker/DOCKERFILE.md for:

• Complete Dockerfile patterns
• Docker Compose best practices
• Security checklist
• Multi-stage build examples
• Commands reference