12장. Porting containers to systemd using Podman

Procedure

1. Create the mysleep.container unit file:

   $ cat $HOME/.config/containers/systemd/mysleep.container
   [Unit]
   Description=The sleep container
   After=local-fs.target
   
   [Container]
   Image=registry.access.redhat.com/ubi10-minimal:latest
   Exec=sleep 1000
   
   [Install]
   # Start by default on boot
   WantedBy=multi-user.target default.target

   In the [Container] section you must specify:

   • Image - container mage you want to tun

   • Exec - the command you want to run inside the container

     This enables you to use all other fields specified in a systemd unit file.

2. Create the mysleep.service based on the mysleep.container file:

   $ systemctl --user daemon-reload

3. Optional: Check the status of the mysleep.service:

   $ systemctl --user status mysleep.service
   ○ mysleep.service - The sleep container
   	 Loaded: loaded (/home/username/.config/containers/systemd/mysleep.container; generated)
   	 Active: inactive (dead)

4. Start the mysleep.service:

   $ systemctl --user start mysleep.service

Verification

1. Check the status of the mysleep.service:

   $ systemctl --user status mysleep.service
   ● mysleep.service - The sleep container
   	 Loaded: loaded (/home/username/.config/containers/systemd/mysleep.container; generated)
   	 Active: active (running) since Thu 2023-02-09 18:07:23 EST; 2s ago
      Main PID: 265651 (conmon)
         Tasks: 3 (limit: 76815)
   	 Memory: 1.6M
      	 CPU: 94ms
   	 CGroup: ...

2. List all containers:

   $ podman ps -a
   CONTAINER ID  IMAGE                            COMMAND               CREATED            STATUS                          PORTS   NAMES
   421c8293fc1b  registry.access.redhat.com/ubi10-minimal:latest               sleep 1000  30 seconds ago   Up 10 seconds ago systemd-mysleep

   Note that the name of the created container consists of the following elements:

   • a systemd- prefix

   • a name of the systemd unit, that is systemd-mysleep

     This naming helps to distinguish common containers from containers running in systemd units. It also helps to determine which unit a container runs in. If you want to change the name of the container, use the ContainerName field in the [Container] section.

     For more information, see the podman-systemd.unit(5) man page on your system.