Quadlets can be debugged with systemd-analyze --generators=true verify example.service (an alternative to podman-system-generator -dryrun)

[eriksjolund]

I have two files my1.container and my2.container. The first one contains a syntax error (the key jImage)

/var/home/test/.config/containers/systemd/my1.container

[Container]
jImage=docker.io/library/alpine
Exec=/bin/sh -c "sleep 300"

/var/home/test/.config/containers/systemd/my2.container

[Container]
Image=docker.io/library/alpine
Exec=/bin/sh -c "sleep 300"

Test 1

1. Run command

   systemd-analyze --user --generators=true verify my1.service
   

   The following output is printed

   quadlet-generator[9752]: converting "my1.container": unsupported key 'jImage' in group 'Container' in 
   /var/home/test/.config/containers/systemd/my1.container
   /usr/lib/systemd/user-generators/podman-user-generator failed with exit status 1.
   Unit my1.service not found.
   

Test 2

1. Run command

   /usr/lib/systemd/system-generators/podman-system-generator --user --dryrun
   

   The following output is printed

   quadlet-generator[9733]: Loading source unit file /var/home/test/.config/containers/systemd/my1.container
   quadlet-generator[9733]: Loading source unit file /var/home/test/.config/containers/systemd/my2.container
   ---my2.service---
   [X-Container]
   Image=docker.io/library/alpine
   Exec=/bin/sh -c "sleep 300"
   
   
   [Unit]
   Wants=podman-user-wait-network-online.service
   After=podman-user-wait-network-online.service
   SourcePath=/var/home/test/.config/containers/systemd/my2.container
   RequiresMountsFor=%t/containers
   
   [Service]
   Environment=PODMAN_SYSTEMD_UNIT=%n
   KillMode=mixed
   ExecStop=/usr/bin/podman rm -v -f -i --cidfile=%t/%N.cid
   ExecStopPost=-/usr/bin/podman rm -v -f -i --cidfile=%t/%N.cid
   Delegate=yes
   Type=notify
   NotifyAccess=all
   SyslogIdentifier=%N
   ExecStart=/usr/bin/podman run --name systemd-%N --cidfile=%t/%N.cid --replace --rm --cgroups=split --sdnotify=conmon -d docker.io/library/alpine /bin/sh -c "sleep 300"
   
   quadlet-generator[9733]: converting "my1.container": unsupported key 'jImage' in group 'Container' in /var/home/test/.config/containers/systemd/my1.container
   

Discussion

The command

systemd-analyze --user --generators=true verify my1.service

seems to be more user-friendly because it just prints the error messages.

It is possible to achieve a similar result by adding > /dev/null

$ /usr/lib/systemd/system-generators/podman-system-generator --user --dryrun > /dev/null
quadlet-generator[9787]: Loading source unit file /var/home/test/.config/containers/systemd/my1.container
quadlet-generator[9787]: Loading source unit file /var/home/test/.config/containers/systemd/my2.container
quadlet-generator[9787]: converting "my1.container": unsupported key 'jImage' in group 'Container' in /var/home/test/.config/containers/systemd/my1.container

(Some additional lines containing Loading source unit file are also listed)

Side note 1: I verified that it is possible to analyse a quadlets in a custom directory path with

QUADLET_UNIT_DIRS=/some/path systemd-analyze --user --generators=true verify my1.service

Side note 2:
The command systemd-analyze verify performs additional checks on
the generated service unit. (See https://www.man7.org/linux/man-pages/man1/systemd-analyze.1.html)

[vrothberg]

Thanks for sharing and kicking off a discussion, @eriksjolund!

I think we should add all this information to the man pages. @ygalblum WDYT?

[ygalblum]

I don't mind adding this to the documentation. Just keep in mind that it is useful only when Quadlet fails to convert the unit file, for example when the key is incorrect. It will not help you if the issue is with the values themselves (for example typo in the image name).
But, as I wrote, I don't mind adding it. @eriksjolund would you like to open a PR?

[eriksjolund]

@eriksjolund would you like to open a PR?

Sure, I'll do that.