Docker Containerization

Docker Containerization

Overview

This skill provides a structured workflow and a set of reusable assets for containerizing applications using Docker. It includes best-practice templates for Dockerfiles, docker-compose.yml, and other configuration files to streamline the containerization process.

Workflow

Follow this workflow to containerize an application.

1. Choose a Dockerfile Template

Based on the service you are containerizing, start with one of the templates in assets/dockerfile-templates/:

• Dockerfile.nextjs: For Next.js frontend applications.
• Dockerfile.fastapi: For FastAPI backend applications.
• Dockerfile.worker: For generic background worker processes.

Copy the most relevant template to the root of your service's directory and rename it to Dockerfile.

For more details on Dockerfile best practices, refer to references/dockerfile-best-practices.md.

2. Set up docker-compose.yml

If you are working with a multi-service application, use the template at assets/docker-compose-template/docker-compose.yml as a starting point. This template defines a typical full-stack setup with a frontend, backend, and database.

Copy this file to the root of your project and customize it for your services.

For a detailed guide on Docker Compose, see references/docker-compose-guide.md.

3. Configure .dockerignore

To optimize the Docker build context and avoid sending unnecessary files to the Docker daemon, use a .dockerignore file. A comprehensive template is available at assets/dockerignore-template/.dockerignore.

Copy this file to the root of your project, and also to each service directory that has its own build context.

4. Configure Health Checks

Health checks are essential for ensuring the reliability of your services. This skill provides guidance and scripts for setting up health checks.

• For a guide on health check strategies, see references/healthcheck-guide.md.
• For a sample web service health check script, see scripts/healthchecks/web-healthcheck.sh.
• For a sample database health check script, see scripts/healthchecks/db-healthcheck.sh.

5. Manage Environment Variables

Properly managing environment variables is key to secure and flexible containerized applications. For a guide on different ways to inject environment variables, see references/env-variable-guide.md.

Resources

This skill provides the following resources:

assets/

Contains template files to be copied and customized.

• dockerfile-templates/: Dockerfile templates for different types of services.
• docker-compose-template/: A docker-compose.yml template for a multi-service application.
• dockerignore-template/: A .dockerignore template.
• database/: Contains an init.sql script for initializing a PostgreSQL database.

scripts/

Contains executable scripts.

• healthchecks/: Shell scripts for container health checks.

references/

Contains detailed documentation.

• dockerfile-best-practices.md: A guide to writing efficient and secure Dockerfiles.
• docker-compose-guide.md: A guide to using Docker Compose.
• healthcheck-guide.md: A guide to configuring health checks.
• env-variable-guide.md: A guide to managing environment variables.