jsonnet: Expose prometheus alerting configuration in $.values.prometheus configuration

[paulfantom]

Description

Describe the big picture of your changes here to communicate to the maintainers why we should accept this pull request.
If it fixes a bug or resolves a feature request, be sure to link to that issue.

Blocked by #1475

Allow passing PrometheusSpec-native alerting configuration in $.values.prometheus instead of alertmanagerName. The latter option is still available, but should be removed post release-0.10.

This is part of aligning configuration options with ones present in CRDs.

Type of change

What type of changes does your code introduce to the kube-prometheus? Put an x in the box that apply.

• CHANGE (fix or feature that would cause existing functionality to not work as expected)
• FEATURE (non-breaking change which adds functionality)
• BUGFIX (non-breaking change which fixes an issue)
• ENHANCEMENT (non-breaking change which improves existing functionality)
• NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Changelog entry

Please put a one-line changelog entry below. Later this will be copied to the changelog file.

Expose prometheus alerting configuration in $.values.prometheus configuration

[paulfantom]

ping @fpetkovski @philipgough as this has potential implications on CMO stack.

[fpetkovski]

Is this a breaking change that needs to be addressed by all clients?

[paulfantom]

No, it is not breaking right now as I maintained backwards compatibility in this PR. However, it is advised to move to a new solution as the intention is to remove alertmanagerName field. This is required to allow using CRD fields as kube-prometheus configuration instead of inventing new fields (like alertmanagerName).

[fpetkovski]

Ack, I saw this line and I thought it was a new variable.