SystemdStatus fact result data selection/restriction

[hjoukl]

Is your feature request related to a problem? Please describe

I wanted to select only specific information from the systemd.SystemdStatus fact result (dictionary).
I.e. get only info on a subset of systemd-Services, by service name.

Describe the solution you'd like

SystemdStatus returns a dictionary {server: {service_name: service_active, ...}}, e.g.:

--> Fact data for: systemd.SystemdStatus
{
    "myserver": {
        "lvm2-lvmetad.service": true,
        "goferd.service": true,
        "systemd-reboot.service": false,
        "systemd-journald.service": true,
        ...

}

I'd like to only show information for a selected subset of services. Since the ad-hoc facts command invocation allows for arguments for the fact gathering, how about to add some mechanism to do that, e.g.

# Possibility 1: restrict service names to gather info about with an additional fact arg e.g.
pyinfra myserver fact systemd.SystemdStatus service_names="sshd-keygen.service, sendmail.service"
# Or maybe list each name separately(?)
pyinfra myserver fact systemd.SystemdStatus service_name="sshd-keygen.service" service_name="sendmail.service"

# Possibility 2: general possibility to restrict dictionary fact return values.
# This could then also work for other facts with dict results.
pyinfra myserver fact systemd.SystemdStatus --select-result-keys="sshd-keygen.service, sendmail.service"
# Or maybe allow for a regex selection - might be overkill(?)
pyinfra myserver fact systemd.SystemdStatus --select-result-keys="(sshd-keygen|sendmail)\.service"

Variations possible, example arg names debatable, of course.

I'm aware there's other possibilities to get at the information already, like

pyinfra myserver exec -- systemctl status goferd.service
pyinfra myserver -- systemctl show goferd.service --property=StatusErrno

Still, it feels like this would complement existing functionality nicely/naturally.

Best regards
Holger

[Fizzadar]

Hi Holger! This is a great idea, I’ve actually implemented just this for v3 here: 0db3632

So you should be able to pass services list to the existing fact to reduce the services queried!

[hjoukl]

Great, looking forward to v3! pyinfra is fabulous. :-)