Allow enabling collectors from the charm

[sudeephb]

If, for whatever reason, the required collector is not activated by the charm automatically, the user has to ssh into the machine and re-run the service with a different configuration. Instead of this, it would be nice to have a way from the charm itself(eg. an action) to enable collectors according to user's choice.

[jneo8]

The issue of it is because there is not configure for single unit in juju.

So imagine you provide this config, and then

• The resource/package will be fetch/install on every units.
• The collector will be active on every units.

I am not sure it's a good practice for debugging on one unit because it will have a side effects. It will be terrible if your grafana throw multiple alerts because the hardware is not there after you gave this config.

https://discourse.charmhub.io/t/per-unit-configuration/2261/4

One way to do this is we still provide this kind of configure but user need to segregate different servers to different application for this approach.

(Currently install two hardware-observer charms may cause an issue because the config file is in the same path)

[jneo8]

One idea from me is maybe we can provide a juju action which helps us to debugging. The action will

• Fetch the required resource and install
• Run prometheus collector's code directly(We maybe need to provide some simple cli in exporter repo)
  • The CLI is to provide a different CLI interface in front of the real prometheus checking code, instead of prometheus API.
• Remove resource

It's like a simple hardware checking script that provide the prometheus metrics output, I think it's enough for us to debugging. And It's easy for us to package it as snap later in the future.

[aieri]

I think this may be already somewhat covered by the hardware redetection action. If this is still needed please reopen.