ruler: Use `notifier` Prometheus package when decoupled from config package.

[bwplotka]

Rationales: Ensure similar logic and usage of powerful relabelling in Thanos Ruler.

Acceptance Criteria

• We don't mainain pkg/alert package and instead use notifier from Prometheus codebase.
• We don't depend on config package that depends on lots of 3rd party packages (k8s, consul, ec2, etc)

Right now our code mimics notifier.

[bwplotka]

First part of it is to move relabel to not use config package: https://github.com/prometheus/prometheus/pull/4955

[bwplotka]

First part merged, whole thing in review: https://github.com/prometheus/prometheus/pull/5025

[markmsmith]

Is this work still planned, or is full relabeling in Ruler already supported in some other way?

[FUSAKLA]

Hi, I believe for now there are the --alert.label-drop= and --label= flags which I'd say cover most of the use cases? Let us knou if you are blocked by this and those labels does not suffice you and we can look more into it. Right now I'm not aware of anyone working on this.

[markmsmith]

We're still in the early stages of figuring out our Thanos alerting setup, so I'm not sure yet if we'll need richer relabeling or not. I was just curious since it seemed like the PR linked above was pretty much there, it just needed a final 👍.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[lilic]

@bwplotka Can we remove this note that links to issue in the docs? https://github.com/thanos-io/thanos/blob/master/docs/components/rule.md#ruler-ha If not all is implemented do you think it makes sense to open a new issue about this?

[bwplotka]

We might need another issue if we need such, so far we did not seen the need ): Anyway the comment in doc is confusing (:

[sjentzsch]

We require full alert relabeling within Thanos Rule. To move forward, we would consider a contribution, but would need some assistance/guidance on how to move forward. Maybe @bwplotka , how would you proceed or what would you suggest as next step?

[yeya24]

IIUC, we still want to use notifier package rather than maintaining our own alert package? I will reopen this issue, feel free to comment and close it if it is unnecessary anymore