Extending systemd generator?

[Lombra]

Hi,

I want to add some extra functionality to quadlets, and I figured systemd generators combined with unit dropin files should come in handy. First I thought of defining entirely new directives, but I think that might not be doable without breaking the existing generator.

One thing I want to do is use a couple of shorthands for the rather verbose Traefik labelling system. Writing your own generators seems simple enough. Ditto for some basic parsing of quadlets, but I'm curious as to whether there are any existing utilities I can use to this end? I was unable to find the source for podman-system-generator.

[eriksjolund]

I was unable to find the source for podman-system-generator.

See the file
https://github.com/containers/podman/blob/main/cmd/quadlet/main.go

Here is how I found it

1. Run command

   /usr/lib/systemd/system-generators/podman-system-generator -help
   

   The following output is printed

   Usage of /usr/lib/systemd/system-generators/podman-system-generator:
     -dryrun
       	Run in dryrun mode printing debug information
     -no-kmsg-log
       	Don't log to kmsg
     -user
       	Run as systemd user
     -v	Print debug information
     -version
       	Print version information and exit
   

2. Clone repo

   git clone https://github.com/containers/podman.git
   

3. Change dir

   cd podman
   

4. Search for Run in dryrun mode printing debug information

    git grep "Run in dryrun mode printing debug information"
   

   The following output is printed

   cmd/quadlet/main.go:    flag.BoolVar(&dryRunFlag, "dryrun", false, "Run in dryrun mode printing debug information")
   

[ygalblum]

Yes, this is the entry point for Quadlet

[Lombra]

Ok, I guess I should have read up more on generators. They only have write access to the final unit directory, and are only intended to be used that way, which I suppose makes sense. I was hoping to write .container.d dropins, and let the existing generator take care of things. I would have to build the ExecStart directive from scratch, unless anyone have any other ideas.