ci: skip steps if successful build for the same commit exists

This will be very handy for release builds, where the very same commit
has usually been build successfully when building the main branch.

.github/workflows/ci.yaml

@@ -27,11 +27,23 @@ concurrency:
   cancel-in-progress: ${{ !(github.ref == 'refs/heads/main' || contains(github.ref, 'refs/tags/')) }}
 
 jobs:
+  check_for_successful_builds_for_same_commit:
+    name: Check for existing successful builds for same commit
+    runs-on: ubuntu-latest
+    outputs:
+      should_skip: ${{ steps.skip_check.outputs.should_skip }}
+    steps:
+      - id: skip_check
+        uses: fkirc/skip-duplicate-actions@v5
+
   verify:
     name: Build & Test
     runs-on: ubuntu-latest
     timeout-minutes: 15
 
+    needs: check_for_successful_builds_for_same_commit
+    if: needs.check_for_successful_builds_for_same_commit.outputs.should_skip != 'true'
+
     steps:
       - uses: actions/checkout@v4
 
@@ -78,6 +90,10 @@ jobs:
     name: Injector Binary & Instrumentation Image Tests
     runs-on: ubuntu-latest
     timeout-minutes: 40
+
+    needs: check_for_successful_builds_for_same_commit
+    if: needs.check_for_successful_builds_for_same_commit.outputs.should_skip != 'true'
+
     steps:
       - uses: actions/checkout@v4
 
@@ -208,12 +224,17 @@ jobs:
   # created), the images are tagged with the version indicated by the tag respectively, and also with latest. That is:
   # Creating a GitHub release (or creating a git tag via other means) will trigger building images tagged with x.y.z
   # meant for production use.
-  build-and-push-images:
+  build_and_push_images:
     name: Build Images
     runs-on: ubuntu-latest
     needs:
       - verify
       - injector_binary_and_instrumentation_image_tests
+    if: |
+      always() &&
+      (needs.verify.result == 'skipped' || needs.verify.result == 'success') &&
+      (needs.injector_binary_and_instrumentation_image_tests.result == 'skipped' || needs.injector_binary_and_instrumentation_image_tests.result == 'success')
+
     # Building all container images across architectures via qemu can take _really_ long, especially if the build cache
     # is empty.
     timeout-minutes: 120
@@ -275,12 +296,13 @@ jobs:
           context: images
           file: images/filelogoffsetsynch/Dockerfile
 
-  publish-helm-chart-dry-run:
+  publish_helm_chart_dry_run:
     name: Publish Helm Chart (Dry Run)
     runs-on: ubuntu-latest
-    if: ${{ ! contains(github.ref, 'refs/tags/') && github.actor != 'dependabot[bot]'}}
     needs:
-      - build-and-push-images
+      - build_and_push_images
+    if: ${{ always() && ! contains(github.ref, 'refs/tags/') && github.actor != 'dependabot[bot]' && needs.build_and_push_images.result == 'success' }}
+
     steps:
       - uses: actions/checkout@v4
 
@@ -295,26 +317,26 @@ jobs:
   # See https://docs.github.com/en/code-security/dependabot/working-with-dependabot/automating-dependabot-with-github-actions#changing-github_token-permissions
   # For that reason, we skip the check whether the Helm chart can still be published for Dependabot update PRs.
   # Those PRs do not change the Helm chart anyway.
-  # Note that the value of the "name" attribute needs to be identical to the publish-helm-chart-dry-run job, since the
+  # Note that the value of the "name" attribute needs to be identical to the publish_helm_chart_dry_run job, since the
   # branch protection rules reference this property, and it is a required check.
-  skip-publish-helm-chart-dry-run-for-dependabot:
+  skip_publish_helm_chart_dry_run_for_dependabot:
     name: Publish Helm Chart (Dry Run)
     runs-on: ubuntu-latest
     if: ${{ ! contains(github.ref, 'refs/tags/') && github.actor == 'dependabot[bot]'}}
     needs:
-      - build-and-push-images
+      - build_and_push_images
 
     steps:
       - name: skipping publish helm chart (dry run)
         run: |
           echo skipping publish helm chart dry run for dependabot commit
 
-  publish-helm-chart:
+  publish_helm_chart:
     name: Publish Helm Chart
     runs-on: ubuntu-latest
     if: ${{ contains(github.ref, 'refs/tags/') && github.actor != 'dependabot[bot]'}}
     needs:
-      - build-and-push-images
+      - build_and_push_images
 
     steps:
       - uses: actions/checkout@v4