feat(hydrator): add inline parameter support to Source Hydrator (#24228)

[sangyeong01]

Summary

Add Helm support to Source Hydrator (alpha feature) to enable using Helm charts with environment-specific value files and parameters.

Currently, Source Hydrator only supports basic Git repository fields (repoURL, targetRevision, path) in the DrySource specification, making it impossible to use with Helm charts that require valueFiles, parameters, or other Helm-specific configurations.

This PR adds a Helm field to the DrySource type and updates the hydrator logic to properly handle Helm configurations, enabling teams to use Source Hydrator with Helm-based applications.

Closes #24228

Changes

• API: Added Helm *ApplicationSourceHelm field to DrySource type in pkg/apis/application/v1alpha1/types.go
• Logic: Updated controller/hydrator/hydrator.go to copy Helm configuration from DrySource to the hydrated ApplicationSource

Example Usage

Before (not supported):

apiVersion: argoproj.io/v1alpha1
kind: Application
spec:
  sourceHydrator:
    drySource:
      repoURL: https://github.com/example/charts.git
      targetRevision: main
      path: my-chart
      # ❌ helm field not supported

After (now supported):

apiVersion: argoproj.io/v1alpha1
kind: Application
spec:
  sourceHydrator:
    drySource:
      repoURL: https://github.com/example/charts.git
      targetRevision: main
      path: my-chart
      helm:  # ✅ Now works
        valueFiles:
          - values-prod.yaml
        parameters:
          - name: image.tag
            value: v1.2.3
        releaseName: my-release

Use Case

Many teams use Helm with environment-specific value files (e.g., values-dev.yaml, values-prod.yaml). Without this support, Source Hydrator cannot be used for Helm applications, limiting its adoption for teams that want to use both Helm and the hydration workflow.

Testing

• Manual testing with Helm chart and multiple value files
• Verified existing functionality remains unaffected
• Confirmed omitempty tag ensures backward compatibility

Future Work

• Add unit tests (will be included in follow-up PR)
• Update CRD schema (will be included in follow-up PR)
• Add documentation (will be included in follow-up PR)

Checklist

• Either (a) I've created an [enhancement proposal](https://github.com/argoproj/argo-cd/issues/new/choose) and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the [Title of the PR](https://argo-cd.readthedocs.io/en/latest/developer-guide/submit-your-pr/#title-of-the-pr)
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by [DCO](https://github.com/argoproj/argoproj/blob/master/community/CONTRIBUTING.md#legal)
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green ([troubleshooting builds](https://argo-cd.readthedocs.io/en/latest/developer-guide/ci/)).
• My new feature complies with the [feature status](https://github.com/argoproj/argoproj/blob/master/community/feature-status.md) guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

Notes

This PR focuses on the core API and logic changes. Follow-up PRs will include:

1. Unit and integration tests
2. CRD schema updates
3. Documentation updates
4. CLI/UI updates if needed

The changes are minimal and backward-compatible, using the omitempty JSON tag to ensure existing DrySource configurations continue to work without modification.

[bunnyshell]

❌ Preview Environment undeployed from Bunnyshell

Available commands (reply to this comment):

• 🚀 /bns:deploy to deploy the environment

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.57%. Comparing base (d59276a) to head (26498c9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #24277      +/-   ##
==========================================
+ Coverage   60.48%   60.57%   +0.09%     
==========================================
  Files         350      350              
  Lines       60208    60212       +4     
==========================================
+ Hits        36417    36474      +57     
+ Misses      20853    20812      -41     
+ Partials     2938     2926      -12     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[crenshaw-dev]

Thanks for the PR! I've marked it as draft while it's being iterated over.

I think we should add kustomize and directory fields at the same time for feature parity with the source field.

I don't think we can save CRD updates, tests, and docs for a follow-up PR. Those need to be part of the initial PR.

[crenshaw-dev]

Thanks for the changes! Can you add docs and e2e tests?

[sangyeong01]

@crenshaw-dev,
I’ve addressed all requested changes, including adding docs and e2e tests. Could you please take another look when you have a chance? Thanks!

[sangyeong01]

Hi @crenshaw-dev,

Thanks for the follow-up. I've updated the PR to address the additional changes you requested. Please let me know what you think when you have a moment. Thanks!

[olivergondza]

nit: Can be rewritten for increased readability:

generate:
  command:
    - sh
    - -c
    - |
      cat <<'EOF'
      {
        "kind": "ConfigMap",
        "apiVersion": "v1",
        "metadata": {
          "name": "plugin-generated-map",
          "namespace": "$ARGOCD_APP_NAMESPACE"
        },
        "data": {
          "message": "plugin-hydrated",
          "source": "hydrator-plugin",
          "content": "$(cat data.txt)"
        }
      }
      EOF