12.6. Automatically generating a systemd unit file using Podman

Procedure

1. Pull the image you want to use on your system. For example, to pull the httpd-24 image:

   # podman pull registry.access.redhat.com/ubi10/httpd-24

2. Optional: List all images available on your system:

   # podman images
   REPOSITORY                                TAG                  IMAGE ID      CREATED        SIZE
   registry.access.redhat.com/ubi10/httpd-24  latest               8594be0a0b57  2 weeks ago    462 MB

3. Create the httpd container:

   # podman create --name httpd -p 8080:8080 registry.access.redhat.com/ubi10/httpd-24
   cdb9f981cf143021b1679599d860026b13a77187f75e46cc0eac85293710a4b1

4. Optional: Verify the container has been created:

   # podman ps -a
   CONTAINER ID  IMAGE                                            COMMAND               CREATED        STATUS      PORTS                   NAMES
   cdb9f981cf14  registry.access.redhat.com/ubi10/httpd-24:latest  /usr/bin/run-http...  5 minutes ago  Created     0.0.0.0:8080->8080/tcp  httpd

5. Generate a systemd unit file for the httpd container:

   # podman generate systemd --new --files --name httpd
   /root/container-httpd.service

6. Display the content of the generated container-httpd.service systemd unit file:

   # cat /root/container-httpd.service
   # container-httpd.service
   # autogenerated by Podman 3.3.1
   # Wed Sep  8 20:41:44 CEST 2021
   
   [Unit]
   Description=Podman container-httpd.service
   Documentation=man:podman-generate-systemd(1)
   Wants=network-online.target
   After=network-online.target
   RequiresMountsFor=%t/containers
   
   [Service]
   Environment=PODMAN_SYSTEMD_UNIT=%n
   Restart=on-failure
   TimeoutStopSec=70
   ExecStartPre=/bin/rm -f %t/%n.ctr-id
   ExecStart=/usr/bin/podman run --cidfile=%t/%n.ctr-id --sdnotify=conmon --cgroups=no-conmon --rm -d --replace --name httpd -p 8080:8080 registry.access.redhat.com/ubi10/httpd-24
   ExecStop=/usr/bin/podman stop --ignore --cidfile=%t/%n.ctr-id
   ExecStopPost=/usr/bin/podman rm -f --ignore --cidfile=%t/%n.ctr-id
   Type=notify
   NotifyAccess=all
   
   [Install]
   WantedBy=multi-user.target default.target

   注意

   Unit files generated by using the --new option do not expect containers and pods to exist. Therefore, they perform the podman run command when starting the service (see the ExecStart line) instead of the podman start command. For example, see section Generating a systemd unit file using Podman.

   • The podman run command uses the following command-line options:

     • The --conmon-pidfile option points to a path to store the process ID for the conmon process running on the host. The conmon process terminates with the same exit status as the container, which allows systemd to report the correct service status and restart the container if needed.
     • The --cidfile option points to the path that stores the container ID.
     • The %t is the path to the run time directory root, for example /run/user/$UserID.
     • The %n is the full name of the service.

7. Copy unit files to /etc/systemd/system for installing them as a root user:

   # cp -Z container-httpd.service /etc/systemd/system

8. Enable and start the container-httpd.service:

   # systemctl daemon-reload
   # systemctl enable --now container-httpd.service
   Created symlink /etc/systemd/system/multi-user.target.wants/container-httpd.service  /etc/systemd/system/container-httpd.service.
   Created symlink /etc/systemd/system/default.target.wants/container-httpd.service  /etc/systemd/system/container-httpd.service.