Corosync cmapctl gatherer

[rtorrero]

This PR adds a gatherer to collect facts from the corosync-cmapctl binary and makes it available through our factsengine

Note that I had to move the utils to a separate package as I was incurring in cyclic dependencies when attempting it to use it in the internal package

[arbulu89]

Nice @rtorrero ,
You will need to rebase from main to get the latest changes, which will break some tests I'm afraid hehe

Besides that, once this or the package_version gatherer PRs are merge, we will need to rebase back again, as they have duplicated code for the command executor.

Finally, this new gatherer must be enabled in the factsengine code, as corosyncconf is right now. Otherwise we cannot really use it.

I would try to compile the binary and run to see that it actually works:

./trento-agent facts gather --gatherer corosync-cmapctl --argument runtime.config.totem.consensus

[arbulu89]

In the package version gatherer I have used _ as "splitter". We should agree on this hehe
- or _?

[rtorrero]

it's not really splitting anything, but reflecting the name of the binary as-is in the same way corosync.conf is the fact key for the corosync configuration gatherer. I still understand the confusion and don't have a strong opinion on this, wdyt?

[rtorrero]

Thanks for the review, indeed I was missing enabling the gatherer in the facts engine. Seems to work correctly now:

INFO[2022-08-04 11:24:01] Using config file: /etc/trento/agent.yaml    
INFO[2022-08-04 11:24:01] Starting corosync-cmapctl facts gathering process 
INFO[2022-08-04 11:24:01] Requested corosync-cmapctl facts gathered    
INFO[2022-08-04 11:24:01] Gathered fact for "corosync-cmapctl" with argument "runtime.config.totem.consensus": 
INFO[2022-08-04 11:24:01] {
  "name": "runtime.config.totem.consensus",
  "value": "36000",
  "check_id": ""
} 

[arbulu89]

Perfect!
Green light from my side

[arbulu89]

I have used log.Errorf in other gatherers, but I guess it doesn't really matter that much.
Once we know how to populate the failed fact gatherings we will need to come back and finish the job hehe