How to Use Podman with Docker Compose: A Step-by-Step Guide to Container Orchestration

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In the evolving landscape of containerization, Podman has emerged as a robust alternative to Docker, bringing unique features like daemonless architecture and rootless containers to the forefront. While Docker Compose has long been a staple for defining and running multi-container Docker applications, the good news is that Podman now offers compatibility with Docker Compose files, enabling users to leverage existing Compose workflows without the Docker daemon. This guide provides a comprehensive walkthrough on how to use Podman with Docker Compose, showcasing how to deploy multi-container applications seamlessly with Podman.

Table of Contents

Understanding Podman and Docker Compose

Podman (Pod Manager) is an open-source container management tool that is part of the libpod library. It offers a Docker-compatible command-line interface (CLI), but unlike Docker, it operates without a central daemon and can run containers as non-root users, enhancing security.

Docker Compose, on the other hand, is a tool that allows users to define and run multi-container Docker applications using a YAML file. The integration of Podman with Docker Compose means you can now use these YAML files with Podman, benefiting from Podman’s advanced features.

Prerequisites

Before proceeding, ensure Podman is installed on your system. Installation instructions for various platforms are available on the official Podman website. Additionally, you need to install podman-compose, a script that provides a Docker Compose-compatible CLI using Podman. You can typically install it via your system’s package manager or Python’s pip.

Step 1: Prepare Your Docker Compose File

For this guide, we’ll create a simple application stack that includes a web server and a database. Create a directory for your project and navigate into it:

mkdir podman-compose-demo && cd podman-compose-demo

Create a docker-compose.yml file:

Create a docker-compose.yml file:

Open the file in a text editor and add the following content:

version: '3'
services:
  web:
    image: nginx:alpine
    ports:
      - "8080:80"
    networks:
      - app-network

  db:
    image: postgres:alpine
    environment:
      POSTGRES_DB: exampledb
      POSTGRES_USER: exampleuser
      POSTGRES_PASSWORD: examplepass
    networks:
      - app-network

networks:
  app-network:
    driver: bridge

This Compose file defines two services: web, an Nginx web server, and db, a PostgreSQL database. Both services are attached to a custom network named app-network.

Step 2: Deploy with Podman Compose

With your docker-compose.yml file ready, you can deploy the application stack using podman-compose. Run the following command in the directory containing your Compose file:

podman-compose up -d

This command reads the docker-compose.yml file and creates the defined services using Podman. The -d flag runs the containers in the background.

Step 3: Verify the Deployment

To ensure your services are running correctly, use the podman ps command to list the running containers:

podman ps

You should see the containers for both the web and db services listed.

To test the web service, open a web browser and navigate to http://localhost:8080. You should see the default Nginx welcome page.

Best Practices and Considerations

Rootless Mode: One of Podman’s key features is the ability to run containers without root privileges. This enhances security by reducing the potential impact of container vulnerabilities.
Compatibility: While podman-compose aims for Docker Compose compatibility, there may be differences or unsupported features. Always test your Compose files thoroughly when migrating from Docker to Podman.
Networking: Podman’s networking model differs from Docker’s. While it offers powerful features, you might need to adjust your network configurations when porting Docker Compose files.

Conclusion

The combination of Podman and Docker Compose offers a powerful, flexible, and secure approach to container orchestration. By leveraging podman-compose, developers can utilize existing Docker Compose workflows while benefiting from Podman’s daemonless and rootless features. This guide has demonstrated how to deploy a simple multi-container application with Podman and Docker Compose, marking just the beginning of what’s possible with these versatile containerization tools. Whether you’re developing locally or orchestrating production deployments, Podman and Docker Compose stand ready to streamline your container management tasks.

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Anastasios Antoniadis

Anastasios Antoniadis is the founder and editor-in-chief of BORDERPOLAR... He is a software engineer, blogger, and avid gamer covering tech, gaming, and coding guides for over 4 years. He is a 2014 graduate of the Department of Informatics and Telecommunications of the University of Athens, an M.Sc. holder in Computer Science, and a Ph.D. student in Program Analysis.