Freight filtering rules

[jessesuen]

Proposed Feature

Subscribing to a git repository can be, in many cases, very noisy and will produce inconsequential freight. Examples include:

• mono repos where there are other directories of unrelated apps
• changes to README.md or unrelated files

Warehouses should allow users to define rules so that only when certain paths are changed, should new freight be generated. e.g. suppose for a kustomize layout, maybe only changes to these directories should produce freight:

apps/
  guestbook/
    base/
    overlays/

Motivation

This will improve usability and filter out noise in the Freightline

Suggested Implementation

Warehouse API spec should introduce a new stanza on filtering rules. Before generating new Freight, it will see if the filtering rules apply and produce Freight accordingly.

NOTE: if we support git webhooks, the git webhook will have information about files that changed. This would avoid a git checkout. But I consider this an optimization and we shouldn't rely on this because we might miss a webhook.

[maksimstankevic]

@krancour @jessesuen I was looking for a new, bit bigger issue, can I pick this one? I have limited free time off work and not sure how long this will take me but if it's fine - really interested to work on this.

[krancour]

@maksimstankevic have at it. We're happy for your assistance!

If I may suggest, simply on account of this being a somewhat complex change, if @jessesuen or myself can review the additions to the Warehouse CRD before you move ahead with corresponding changes to the controller, I think it would help to make sure we're all on the same page early in the process.

[maksimstankevic]

@krancour @jessesuen could you please check and comment, main...maksimstankevic:kargo:feature/1270. I thought we could use similar approach as with AllowTags/IgnoreTags in ImageSubscription but use list of regexps in both GitSubscription's ScanPaths and IgnorePaths for more flexibility.

[krancour]

@maksimstankevic I am so sorry for the delayed review. I think that is a good starting point.

[maksimstankevic]

@krancour, hey, I submitted #1477 for this one, please, take a look when you have a sec

[krancour]

This was closed by #1477