Custom Git Commit Status Prefix

[clarkdoan]

Resolves: #194

Problem

When setting a git commit status the controller only uses the event.InvolvedObject.Kind and event.InvolvedObject.Name to generate the status' context. This does not allow multiple clusters to update the commit status if they use the same Kustomization name.

Proposed Solution

The event that is passed to the formatNameAndDescription function contains a Metadata field.

The AlertSpec contains a Summary field which is used as a Short description of the impact and affected cluster.

The event handler copies the value of the Summary field from the AlertSpec to the Metadata field of the event.

This PR checks the value of the Metadata field to see if there is a summary key. If the key exists then the summary value will be prepended to the context of the commit status. This will allow the user to set the prefix of the commit status.

[stefanprodan]

Please change the Summary description in code and run make test then commit the generated CRDs. Append this to the field description: "For commit status updates, this field is used to prefix the status message.".

[phillebaba]

We need to do some testing with this feature regarding different provider length constraints and format constraints, as this will allow users to inject arbitrary text into the status ID.

[stefanprodan]

@phillebaba I think we should trim the summary to a small number of characters, as you said we need to determine which number that is.

[phillebaba]

Github has a limit of 140 last time I hit this issue but is not documented. Gitlab has something similar while Azure DevOps has a much larger limit. The issue is that none of these limits are documented.

[phillebaba]

I would actually prefer to hold off on this PR and instead implement a more generic solution as proposed here.
fluxcd/flux2#1529