Convert delete-preview action from Docker to composite (#21183)

* Convert delete-preview action from Docker to composite

Fix permission issues on GitHub-hosted runners by converting the
delete-preview action from a Docker container action to a composite
action. This resolves credential access problems where
GOOGLE_APPLICATION_CREDENTIALS set by setup-environment was not
accessible inside the Docker container.

Changes:
- Convert metadata.yml from 'using: docker' to 'using: composite'
- Move commands from entrypoint.sh to composite action steps
- Remove Dockerfile and entrypoint.sh (no longer needed)
- Preserve all functionality: previewctl install and delete-preview

The composite action runs directly on the runner, allowing proper
access to GCP credentials and environment variables set by the
setup-environment action.

Co-authored-by: Ona <[email protected]>

* Add container to delete job for leeway availability

The composite action requires leeway to be available, which is only
present in the dev-environment container. Run the entire delete job
in the container to provide leeway and other required tools.

This matches the pattern used in preview-env-gc.yml for the stale job.

Co-authored-by: Ona <[email protected]>

* Fix duplicate workflow runs on PR push

Remove push trigger and use pull_request with synchronize type to
prevent duplicate workflow runs when pushing to a PR branch.

Previously, both push and pull_request events fired when pushing to a
PR branch, causing the workflow to run twice in parallel.

Changes:
- Remove push trigger (branches-ignore: main)
- Add synchronize and reopened to pull_request types
- Keep opened and edited for PR creation and description updates

The synchronize event fires when commits are pushed to a PR branch,
replacing the need for the push trigger.

Co-authored-by: Ona <[email protected]>

* Add comment explaining pull_request trigger types

Document the purpose of each pull_request event type to clarify when
the workflow runs and why each type is needed.

Co-authored-by: Ona <[email protected]>

---------

Co-authored-by: Ona <[email protected]>

Author: geropl

.github/actions/delete-preview/Dockerfile

@@ -0,0 +1,26 @@
+name: "Delete preview environment"
+description: "Deletes a preview environment"
+inputs:
+    name:
+        description: "The name of the preview environment"
+        required: true
+runs:
+    using: "composite"
+    steps:
+      - name: Install previewctl
+        shell: bash
+        run: |
+          set -euo pipefail
+          leeway run dev/preview/previewctl:install
+
+      - name: Delete preview environment
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          export TF_INPUT=0
+          export TF_IN_AUTOMATION=true
+          TF_VAR_preview_name="$(previewctl get-name --branch "${{ inputs.name }}")"
+          export TF_VAR_preview_name
+
+          leeway run dev/preview:delete-preview

.github/actions/delete-preview/action.yml

@@ -7,10 +7,11 @@ permissions:
   packages: read
 on:
   pull_request:
-    types: [ opened, edited ]
-  push:
-    branches-ignore:
-      - main
+    # opened: PR is created
+    # synchronize: Commits are pushed to the PR branch
+    # reopened: PR is reopened
+    # edited: PR description/title is edited (for checkbox updates like [x] /werft with-preview)
+    types: [ opened, synchronize, reopened, edited ]
   workflow_dispatch:
     inputs:
       recreate_vm:

.github/actions/delete-preview/entrypoint.sh

@@ -14,6 +14,9 @@ jobs:
   delete:
     if: github.event.ref_type == 'branch' || github.event.inputs.name != ''
     runs-on: ubuntu-latest
+    container:
+      image: eu.gcr.io/gitpod-core-dev/dev/dev-environment:main-gha.34181
+      options: --user root
     steps:
       - uses: actions/checkout@v4
       - name: Setup Environment