Fix position files

[dstathis]

Issue

Fixes #109

Solution

Use different names for the positions files

Testing Instructions

Relate over loki_push_api and check systemctl status snap.grafana-agent.grafana-agent.service

Release Notes

Fixed an issue where Grafana Agent could not start if related to loki.

[rbarry82]

LGTM.

Amazing that every different scraper needs its own YAML instead of just making a new key.

Obviously the linter, again...

[Abuelodelanada]

Shouldn't we put these in constants, so it is easy to modify in the future?

[rbarry82]

For me, that's six of one and half a dozen of another. The only place the constant would be used is here, and it's swapping one hardcoded string for another.

If Grafana Agent isn't able to share, I wonder instead if we should make the name more dynamic, so it's something like:

name = # generate_some_meaningful_identifier
{
  "name": name,
  "positions": { "filename": f"/run/{name}_positions.yaml" },
  ..
}

To future proof a little against the possibility of some other possible need for a position file coming up in the future and us forgetting that bad things happen if they share.

[awnns]

I played around a little with this. You can also set a folder in which the grafana-agent will generate its own position files based on the job name so you don't have to set the name manually for every job. There's a field on the same level as "configs" called "positions_directory" (see https://grafana.com/docs/agent/latest/configuration/logs-config/). I had to put it in /var/snap/[...] to get it to work permissions wise, but that did the trick for me at least. Have you considered it?

[rbarry82]

I don't know if any of us came across that in the docs, but it's a great find we should definitely use. Thanks @awnns !