8.5. Vagens de inicialização automática usando systemd

Procedimento

1. Criar uma cápsula vazia, por exemplo, chamada systemd-pod:

   $ podman pod create --name systemd-pod
   11d4646ba41b1fffa51c108cbdf97cfab3213f7bd9b3e1ca52fe81b90fed5577

2. Liste todas as cápsulas:

   $ podman pod ps
   POD ID        NAME         STATUS   CREATED         # OF CONTAINERS  INFRA ID
   11d4646ba41b  systemd-pod  Created  40 seconds ago  1                8a428b257111
   11d4646ba41b1fffa51c108cbdf97cfab3213f7bd9b3e1ca52fe81b90fed5577

3. Criar dois recipientes na cápsula vazia. Por exemplo, para criar container0 e container1 em systemd-pod:

   $ podman create --pod systemd-pod --name container0 registry.access.redhat.com/ubi8 top
   $ podman create --pod systemd-pod --name container1 registry.access.redhat.com/ubi8 top

4. Liste todas as cápsulas e recipientes associados a elas:

   $ podman ps -a --pod
   CONTAINER ID  IMAGE                                   COMMAND  CREATED        STATUS         PORTS   NAMES               POD ID        PODNAME
   24666f47d9b2  registry.access.redhat.com/ubi8:latest  top      3 minutes ago  Created                container0          3130f724e229  systemd-pod
   56eb1bf0cdfe  k8s.gcr.io/pause:3.2                             4 minutes ago  Created                3130f724e229-infra  3130f724e229  systemd-pod
   62118d170e43  registry.access.redhat.com/ubi8:latest  top      3 seconds ago  Created                container1          3130f724e229  systemd-pod

5. Gerar o arquivo da unidade do sistema para o novo módulo:

   $ podman generate systemd --files --name systemd-pod
   /home/user1/pod-systemd-pod.service
   /home/user1/container-container0.service
   /home/user1/container-container1.service

   Observe que são gerados três arquivos de unidade do sistema, um para o módulo systemd-pod e dois para os recipientes container0 e container1.

6. Exibir o arquivo da unidade pod-systemd-pod.service:

   $ cat pod-systemd-pod.service
   # pod-systemd-pod.service
   # autogenerated by Podman 2.0.3
   # Tue Jul 28 14:00:46 EDT 2020
   
   
   [Unit]
   Description=Podman pod-systemd-pod.service
   Documentation=man:podman-generate-systemd(1)
   Wants=network.target
   After=network-online.target
   Requires=container-container0.service container-container1.service
   Before=container-container0.service container-container1.service
   
   [Service]
   Environment=PODMAN_SYSTEMD_UNIT=%n
   Restart=on-failure
   ExecStart=/usr/bin/podman start c852fbaba568-infra
   ExecStop=/usr/bin/podman stop -t 10 c852fbaba568-infra
   ExecStopPost=/usr/bin/podman stop -t 10 c852fbaba568-infra
   PIDFile=/run/user/1000/containers/overlay-containers/a7ff86382608add27a03ac2166d5d0164199f01eadf80b68b06a406c195105fc/userdata/conmon.pid
   KillMode=none
   Type=forking
   
   [Install]
   WantedBy=multi-user.target default.target

   • A linha Requires na seção [Unit] define as dependências dos arquivos das unidades container-container0.service e container-container1.service. Ambos os arquivos unitários serão ativados.
   • As linhas ExecStart e ExecStop na seção [Service] iniciam e param o infracontainer, respectivamente.

7. Exibir o arquivo da unidade container-container0.service:

   $ cat container-container0.service
   # container-container0.service
   # autogenerated by Podman 2.0.3
   # Tue Jul 28 14:00:46 EDT 2020
   
   [Unit]
   Description=Podman container-container0.service
   Documentation=man:podman-generate-systemd(1)
   Wants=network.target
   After=network-online.target
   BindsTo=pod-systemd-pod.service
   After=pod-systemd-pod.service
   
   [Service]
   Environment=PODMAN_SYSTEMD_UNIT=%n
   Restart=on-failure
   ExecStart=/usr/bin/podman start container0
   ExecStop=/usr/bin/podman stop -t 10 container0
   ExecStopPost=/usr/bin/podman stop -t 10 container0
   PIDFile=/run/user/1000/containers/overlay-containers/12e85378f2854b8283f791974494a02aa6c92630d76d1050237839b61508a008/userdata/conmon.pid
   KillMode=none
   Type=forking
   
   [Install]
   WantedBy=multi-user.target default.target

   • A linha BindsTo na seção [Unit] define a dependência do arquivo da unidade pod-systemd-pod.service
   • As linhas ExecStart e ExecStop na seção [Service] iniciam e param o container0 respectivamente.

8. Exibir o arquivo da unidade container-container1.service:

   Container-container1.serviço de $ cat

9. Copiar todos os arquivos gerados para $HOME/.config/systemd/user para instalação como usuário não-rootal:

   $ cp pod-systemd-pod.service container-container0.service container-container1.service $HOME/.config/systemd/user

10. Habilite o serviço e comece com o login do usuário:

    $ systemctl enable --user pod-systemd-pod.service
    Created symlink /home/user1/.config/systemd/user/multi-user.target.wants/pod-systemd-pod.service → /home/user1/.config/systemd/user/pod-systemd-pod.service.
    Created symlink /home/user1/.config/systemd/user/default.target.wants/pod-systemd-pod.service → /home/user1/.config/systemd/user/pod-systemd-pod.service.

    Note que o serviço pára no logout do usuário.