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content/blog/docker-to-podman.md

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+date = '2025-02-16T12:29:47+01:00'
+draft = true
+title = 'From Docker to Podman'
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+
+[Podman](https://podman.io/) is a tool that can run OCI containers and aims at being a drop replacement for [Docker](https://www.docker.com/) but with some differences
+- no daemon
+- rootless by default
+- only run containers, do not build images
+
+However, there a subtle differences that makes it hard to directly replace docker by podman.
+
+# Usage 
+
+The main difference with docker is that podman does not use a daemon. The consequence of that is that the containers are running with the user that started them.
+
+## Use container as a service
+
+There are a couple of things to be able to use podman containers as a service
+
+### linger
+
+As the container is started in the session of the user that started it, by default, when the user closes her session, the containers will be stopped.
+To prevent that, you need to enabled linger
+ 
+`loginctl enable-linger $USER`
+
+[Reference](https://github.com/containers/podman/blob/b03466c/troubleshooting.md#17-rootless-containers-exit-once-the-user-session-exits)
+
+### restart
+
+The user that is running the containers need to have a restart service for podman:
+ `systemctl --user edit podman-restart.service`
+
+{{< highlight SYSTEMD "linenos=inline">}}
+[Service]
+ExecStart=
+ExecStart=/usr/bin/podman $LOGGING start --all
+ExecStop=
+ExecStop=/bin/sh -c '/usr/bin/podman $LOGGING stop $(/usr/bin/podman container ls -q)'
+{{</ highlight >}}
+
+The service need to be enabled: `systemctl --user enable podman-restart.service`
+
+Once this is setup, all the containers will be stopped at shutdown and started at startup
+
+[Reference](https://nts.strzibny.name/systemd-user-services/)
+
+### port
+
+By default, podman cannot create containers that bind to ports < 1024
+There is a few of options to solve that. 
+The one I recommend is using a tool like [redir](https://github.com/troglobit/redir) that will listen to privileged port and forward to an unprivileged one used by podman.
+
+Install redir:
+
+`sudo apt install redir`
+
+`sudo nvim /etc/systemd/system/redir.service`
+{{< highlight SYSTEMD "linenos=inline">}}
+[Unit]
+Description=Redirect tcp port 443 to 8443 with redir
+
+[Service]
+ExecStart=/bin/redir -sn :443 127.0.0.1:8443
+
+[Install]
+WantedBy=multi-user.target
+{{</ highlight >}}
+
+`sudo systemctl enable --now redir.service`
+
+[Reference](https://linuxconfig.org/how-to-bind-a-rootless-container-to-a-privileged-port-on-linux)
+
+## Compose
+
+`podman compose` is only supported starting version 4.7 of podman
+You will need to install `podman-compose` aside podman
+To be compatible with both podman and docker
+
+Although the name `docker-compose.yml` is supported, I prefer using `compose.yml`
+
+
+## Socket
+
+Docker uses a daemon that is accessible from a socket.
+This is used by a bunch of tools to automate tasks related to docker, get info on running containers or automatically configure things based on the labels defined in a container.
+
+Podman being daemon-less,