Problem

Both the SCM Provider generator and Pull Request generator are very good tools for different and valid use cases, but the limitation is that they cannot be used together in a Matrix generator:

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: myapp
spec:
  generators:
    - matrix:
        generators:
        - scmProvider:
            github:
              organization: myorg
        - pullRequest:
            github:
              owner: myorg
              repo: < Cannot do this here! >
  template:
   ....

We are trying to adopt/migrate to ArgoCD and this is sort of a major blocker. Our testing ecosystem depends on engineers being able to deploy PRs to validate features. According to Pull Request generator docs, "this [the genrator] fits well with the style of building a test environment when you create a pull request". However, when using ApplicationSets, we cannot really have one ApplicationSet with SCM generator and one with Pull Request generator.

Proposed solution

Add an extra attribute to SCM generator:

  generators:
  - scmProvider:
      github:
        organization: myorg
        allBranches: false
        allPullRequests: true

Similar to allBranches, allPullRequests would create a new ArgoCD app for the open PRs, and could also have a PRMatch filter.

So it would be like embedding the Pull Request generator into the SCM generator.

Any feedback/comments would be appreciated.