Docker-Compose Podman

Prerequisites

• docker-compose
• A Linux host – I use a Debian 11 KVM virtual machine
• Time

Setup

There are two routes here that I considered.

Use Podman from Debian

This should work just fine, but I would make sure that there isn’t a feature you are missing out on due to running Debian’s older version. Check Podman’s release page against Debian’s package version. At the time of this writing, it is a matter of version 3.3.0 vs 3.0.1.

This method is quite simple, just run apt install podman

(what I did) Use Kubic’s Podman package

I found the Kubic Package Repository for Podman on Podman’s install page. I noticed that there are repositories for not only Ubuntu, but Centos, Debian, Fedora, and Raspbian too.

To use this with Debian 11, run the following as root…

echo 'deb https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/Debian_11/ /' | sudo tee /etc/apt/sources.list.d/podman.list

curl -LSs https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/Debian_11/Release.key | sudo apt-key add -

Configuration

For the most part, you have a pretty sane Podman setup at this point. You should be able to run podman commands just fine. I did perform one optimization and some additional setup to accommodate the migration from docker-compose.

(optional) Change the Storage Driver

By default, Podman uses the overlay storage driver. I use BTRFS as my file system for Linux systems so I would like to leverage its builtin features for container storage.

Open /etc/containers/storage.conf with your favorite editor and change the line, driver = "overlay" to driver = "btrfs".

sed -i 's/^driver *= *.*/driver = "btrfs"/' /etc/containers/storage.conf

This is a one line solution too.

Run man containers-storage.conf for more details and other drivers you might be interested in.

Enable systemd Units for Docker API support

• podman.socket – This is what provides the Docker API Unix domain socket at /var/run/podman/podman.sock
• podman.service – This is a direct dependency of podman.socket and provides the Podman API.
• podman-restart.service – This makes sure that containers with a restart policy set are restarted.

To enable all of the above…

systemctl enable --now podman.socket podman.service podman-restart.service

docker-compose up -d

To run your docker-compose.yml with your project with docker-compose, you will need to export the following to your shell…

export DOCKER_HOST="unix:///var/run/podman/podman.sock"

This tells the docker-compose command to speak to the Podman socket.

Now, execute docker-compose up -d, your containers should now be up and running. Verify by running podman ps.

Prologue

You now have a system using Podman with docker-compose!

Next steps will be migrating to something like a Kubernetes YAML or systemd unit files.

re: podman generate