podman-generate-systemd deprecato – usare Podman Quadlet

ByLuckysideburn

November 12, 2024

Salve a tutti. Oggi fortunatamente ho un’oretta libera dal lavoro e prima di tornare a casa vorrei sistemare un tema che da anni ormai sto rimandando. Sulla VM dove eseguo il mio blog ed accolli.it ho tantissimi container lanciati con Podman e che non sono servizi Systemd.

La cosa mi crea un senso di confusione per cui meglio procedere sistemando la situazione.

Inizierò usando podman-generate-systemd ma è deprecato (lo trovavo molto comodo) in favore di Podman Quadlet dalla versione 4.4 di Podman. In realtà mi ci devo abituare perché in effetti è molto più sensato e ci permette di definire il container stesso nella unit Systemd. Come riportato nell’articolo https://blogs.gnome.org/alexl/2021/10/12/quadlet-an-easier-way-to-run-system-containers/ di Alexander Larsson verrebbe più o meno così:

[Unit]
Description=Redis container

[Container]
Image=docker.io/redis
PublishPort=6379:6379
User=999

[Service]
Restart=always

[Install]
WantedBy=local.target

Alla vecchia maniera ho dovuto svolgere i seguenti passi che lascio per chi dovesse avere una versione antecedente alla 4.4 di Podman.

Prima di tutto prendere la lista di tutti i container running sul nodo con un for per generare i file .service.

[root@web01]:~ >> mkdir my_systemd_units
[root@web01]:~ >>
[root@web01]:~ >>
[root@web01]:~ >>
[root@web01]:~ >> cd my_systemd_units/
[root@web01]:~/my_systemd_units >> for i in $(podman ps --format '{{.Names}}' | grep -v infra); do podman generate systemd --restart-policy=always --new --files --name -t 1 $i; done

Please refer to podman-systemd.unit(5) for details.
/root/container-mysql.service

Please refer to podman-systemd.unit(5) for details.
/root/container-devopstribe.service

Please refer to podman-systemd.unit(5) for details.
/root/container-cartediaccollo2.service

Please refer to podman-systemd.unit(5) for details.
/root/container-mongodb.service

Please refer to podman-systemd.unit(5) for details.
/root/container-grafana.service

Please refer to podman-systemd.unit(5) for details.
/root/container-registry.service


Please refer to podman-systemd.unit(5) for details.
/root/container-prometheus.service


[root@web01]:~/my_systemd_units >> cp *.service /usr/lib/systemd/system/
[root@web01]:~/my_systemd_units >>

Riavvio i servizi e li abilito al boot

[root@web01]:~/my_systemd_units >> for i in $(ls -lart /usr/lib/systemd/system/ | grep 'container-' | awk '{ print $9}'); do systemctl restart $i && systemctl enable $i; done

See system logs and 'systemctl status container-getty@.service' for details.
Created symlink /etc/systemd/system/default.target.wants/container-registry.service → /usr/lib/systemd/system/container-registry.service.
Created symlink /etc/systemd/system/default.target.wants/container-prometheus.service → /usr/lib/systemd/system/container-prometheus.service.
Created symlink /etc/systemd/system/default.target.wants/container-mysql.service → /usr/lib/systemd/system/container-mysql.service.
Created symlink /etc/systemd/system/default.target.wants/container-mongodb.service → /usr/lib/systemd/system/container-mongodb.service.
Created symlink /etc/systemd/system/default.target.wants/container-grafana.service → /usr/lib/systemd/system/container-grafana.service.
Created symlink /etc/systemd/system/default.target.wants/container-devopstribe.service → /usr/lib/systemd/system/container-devopstribe.service.
Created symlink /etc/systemd/system/default.target.wants/container-cartediaccollo2.service → /usr/lib/systemd/system/container-cartediaccollo2.service.

Controllo che sia tutto running da systemctl

[root@web01]:~/my_systemd_units >> for i in $(ls -lart  /usr/lib/systemd/system/ | grep 'container-' | awk '{ print $9}'); do systemctl status $i; done
Failed to get properties: Unit name container-getty@.service is neither a valid invocation ID nor unit name.
● container-registry.service - Podman container-registry.service
   Loaded: loaded (/usr/lib/systemd/system/container-registry.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:58:46 UTC; 2min 6s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2542077 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 1.3M
   CGroup: /system.slice/container-registry.service
           └─2542077 /usr/bin/conmon --api-version 1 -c 91c8e4006588b0c0595660280cde6b54560e5896cbeec7ce2e2d56ec739052f1 -u 91c8e4006588b0c0595660280cde6b54560e5896cbeec7ce2e2d56ec739052f1 -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:58:45 web01 systemd[1]: Starting Podman container-registry.service...
Nov 12 17:58:46 web01 systemd[1]: Started Podman container-registry.service.
Nov 12 17:58:46 web01 podman[2541923]: 91c8e4006588b0c0595660280cde6b54560e5896cbeec7ce2e2d56ec739052f1
● container-prometheus.service - Podman container-prometheus.service
   Loaded: loaded (/usr/lib/systemd/system/container-prometheus.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:58:48 UTC; 2min 8s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2542169 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 1.7M
   CGroup: /system.slice/container-prometheus.service
           └─2542169 /usr/bin/conmon --api-version 1 -c 6c3bd4ffe7195989b448ffa6bed8891812912398b39ac4d8a5e6bf278ff64d9f -u 6c3bd4ffe7195989b448ffa6bed8891812912398b39ac4d8a5e6bf278ff64d9f -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:58:47 web01 systemd[1]: Starting Podman container-prometheus.service...
Nov 12 17:58:48 web01 systemd[1]: Started Podman container-prometheus.service.
Nov 12 17:58:48 web01 podman[2542127]: 6c3bd4ffe7195989b448ffa6bed8891812912398b39ac4d8a5e6bf278ff64d9f
● container-mysql.service - Podman container-mysql.service
   Loaded: loaded (/usr/lib/systemd/system/container-mysql.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:58:52 UTC; 2min 5s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2542262 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 1.2M
   CGroup: /system.slice/container-mysql.service
           └─2542262 /usr/bin/conmon --api-version 1 -c b8279692cb99652dedfa4d59b88d2ec4d50d8e1c4541e4cc5bf00ad1e32062b2 -u b8279692cb99652dedfa4d59b88d2ec4d50d8e1c4541e4cc5bf00ad1e32062b2 -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:58:49 web01 systemd[1]: Starting Podman container-mysql.service...
Nov 12 17:58:52 web01 systemd[1]: Started Podman container-mysql.service.
Nov 12 17:58:52 web01 podman[2542221]: b8279692cb99652dedfa4d59b88d2ec4d50d8e1c4541e4cc5bf00ad1e32062b2
● container-mongodb.service - Podman container-mongodb.service
   Loaded: loaded (/usr/lib/systemd/system/container-mongodb.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:58:56 UTC; 2min 1s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2542589 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 1.2M
   CGroup: /system.slice/container-mongodb.service
           └─2542589 /usr/bin/conmon --api-version 1 -c 289a78dcf214c4c27dac624d4c74a44037697a85f954bb63212c51d15565d99e -u 289a78dcf214c4c27dac624d4c74a44037697a85f954bb63212c51d15565d99e -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:58:53 web01 systemd[1]: Starting Podman container-mongodb.service...
Nov 12 17:58:56 web01 systemd[1]: Started Podman container-mongodb.service.
Nov 12 17:58:56 web01 podman[2542345]: 289a78dcf214c4c27dac624d4c74a44037697a85f954bb63212c51d15565d99e
● container-grafana.service - Podman container-grafana.service
   Loaded: loaded (/usr/lib/systemd/system/container-grafana.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:59:00 UTC; 1min 58s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2542713 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 1.2M
   CGroup: /system.slice/container-grafana.service
           └─2542713 /usr/bin/conmon --api-version 1 -c bc437bff8a6a9548d72f22d75dc9bfb97cf60d1f9b1bd5b5add5b3197e3778c9 -u bc437bff8a6a9548d72f22d75dc9bfb97cf60d1f9b1bd5b5add5b3197e3778c9 -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:58:57 web01 systemd[1]: Starting Podman container-grafana.service...
Nov 12 17:59:00 web01 systemd[1]: Started Podman container-grafana.service.
Nov 12 17:59:00 web01 podman[2542652]: bc437bff8a6a9548d72f22d75dc9bfb97cf60d1f9b1bd5b5add5b3197e3778c9
● container-devopstribe.service - Podman container-devopstribe.service
   Loaded: loaded (/usr/lib/systemd/system/container-devopstribe.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:59:05 UTC; 1min 53s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2542851 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 2.6M
   CGroup: /system.slice/container-devopstribe.service
           └─2542851 /usr/bin/conmon --api-version 1 -c c044fc2a723700585572e34d889425266f12b9c226b3f86dd8921c0b54979aed -u c044fc2a723700585572e34d889425266f12b9c226b3f86dd8921c0b54979aed -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:59:00 web01 systemd[1]: Starting Podman container-devopstribe.service...
Nov 12 17:59:05 web01 systemd[1]: Started Podman container-devopstribe.service.
Nov 12 17:59:05 web01 podman[2542771]: c044fc2a723700585572e34d889425266f12b9c226b3f86dd8921c0b54979aed
● container-cartediaccollo2.service - Podman container-cartediaccollo2.service
   Loaded: loaded (/usr/lib/systemd/system/container-cartediaccollo2.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2024-11-12 17:59:10 UTC; 1min 48s ago
     Docs: man:podman-generate-systemd(1)
 Main PID: 2543177 (conmon)
    Tasks: 1 (limit: 22914)
   Memory: 1.2M
   CGroup: /system.slice/container-cartediaccollo2.service
           └─2543177 /usr/bin/conmon --api-version 1 -c fc9be83b3cc3514d0439a47badc195c358c14f77e6c209c77394281255327f57 -u fc9be83b3cc3514d0439a47badc195c358c14f77e6c209c77394281255327f57 -r /usr/bin/runc -b /var/lib/con>

Nov 12 17:59:08 web01 systemd[1]: container-cartediaccollo2.service: Failed with result 'exit-code'.
Nov 12 17:59:08 web01 systemd[1]: Stopped Podman container-cartediaccollo2.service.
Nov 12 17:59:08 web01 systemd[1]: Starting Podman container-cartediaccollo2.service...
Nov 12 17:59:10 web01 systemd[1]: Started Podman container-cartediaccollo2.service.
Nov 12 17:59:10 web01 podman[2543019]: fc9be83b3cc3514d0439a47badc195c358c14f77e6c209c77394281255327f57

Come sarebbe usando Podman Quadlet?

Come riportato anche in questo articolo https://www.redhat.com/en/blog/quadlet-podman con Quadlet è possibile istrumentare delle unit Systemd che abbiano al loro interno direttamente i parametri che esprimono i nostri container… Ne riporto di seguito un estratto.

ContainerName=name–name name
ContainersConfModule=/etc/nvd.conf–module=/etc/nvd.conf
DNS=192.168.55.1–dns=192.168.55.1
DNSOption=ndots:1–dns-option=ndots:1
DNSSearch=example.com–dns-search example.com
DropCapability=CAP–cap-drop=CAP
Entrypoint=/foo.sh–entrypoint=/foo.sh
Environment=foo=bar–env foo=bar
EnvironmentFile=/tmp/env–env-file /tmp/env
EnvironmentHost=true–env-host
Exec=/usr/bin/commandCommand after image specification – /usr/bin/command

Ricapitolando, una unit Systemd verrebbe più o meno così:

[Unit]
Description=The sleep container
After=local-fs.target

[Container]
Image=registry.access.redhat.com/ubi9-minimal:latest
Exec=sleep 1000

[Install]
# Start by default on boot
WantedBy=multi-user.target default.target

Supporta diversi tipi di file:

  • .kube (manifest di pod Kubernetes)
  • .network (container network)
  • .container (definizione container)
  • .volume (volumi per la persistenza dei container)

Non andiamo più a definire nelle unit .service dei container espandendo il comando “podman run… ” sostanzialmente, ma andiamo ad esprimere una unit che definisce i parametri necessari al container.

Direi che è molto utile e come sempre, per alcuni tipi di workload e quando non è necessario usare Kubernetes, anche delle VMs con Podman vanno più che bene.

A presto!