fix GHA runner version updater workflow and enable it (#3417)

[static]

Signed-off-by: Mateusz Błażejewski <mateusz.blazejewski@digitalasset.com>

Author: mblaze-da

.github/workflows/bump_gha_runner_version.yml

@@ -1,24 +1,37 @@
-name: Bump GHA runner version (WIP)
+name: Bump GHA runner version
 on:
-  # schedule:
-  #   - cron: '30 6 1,15 * *'  # Monthly on the 1st and 15th at 06:30
+  schedule:
+    - cron: '30 6 1,15 * *'  # Monthly on the 1st and 15th at 06:30
   workflow_dispatch:
 
 jobs:
   bump_gha_runner_version:
-    runs-on: ubuntu-24.04
     name: Bump GHA runner version
+    runs-on: self-hosted-k8s-small
+    container:
+      image: us-central1-docker.pkg.dev/da-cn-shared/ghcr/digital-asset/decentralized-canton-sync-dev/docker/splice-test-ci:0.3.12
     steps:
       - name: Checkout code
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: Setup
+        shell: bash
+        run: ./.github/actions/scripts/common_setup.sh
+
+      - name: Set up Nix (Self hosted)
+        uses: ./.github/actions/nix/setup_nix
+        with:
+          cache_version: 7
+          artifactory_user: dummy
+          artifactory_password: dummy
 
       - name: Check for the latest version and create a PR to splice
         uses: ./.github/actions/nix/run_bash_command_in_nix
         with:
           cmd: |
             git config user.email "splice-maintainers@digitalasset.com"
             git config user.name "DA Automation"
-            ./scripts/bump_gha_runner_version.sh
+            ./scripts/bump-gha-runner-version.sh
           additional_nix_args: "--keep GH_TOKEN"
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

scripts/bump-gha-runner-version.sh

@@ -19,6 +19,8 @@ runner_digest=$(
   | yq '.Digest'
 )
 
+echo "The newest available image is ghcr.io/actions/actions-runner:${runner_version}@${runner_digest}"
+
 docker_runner_file="${SPLICE_ROOT}/cluster/images/splice-test-docker-runner/Dockerfile"
 runner_hook_file="${SPLICE_ROOT}/cluster/images/splice-test-runner-hook/Dockerfile"
 
@@ -34,10 +36,14 @@ if git diff --exit-code --quiet "${docker_runner_file}" "${runner_hook_file}"; t
   exit 0
 fi
 
+echo "GHA runner version is not up to date. Testing image build..."
+
 make --directory "${SPLICE_ROOT}" --jobs \
   cluster/images/splice-test-docker-runner/docker-build \
   cluster/images/splice-test-runner-hook/docker-build
 
+echo "Creating a PR..."
+
 git add --all
 updated_branch="gha-runner-version-bump-$(date +%Y-%m-%d)"
 git switch -c "${updated_branch}"
@@ -50,3 +56,5 @@ gh pr create \
   --title "Bump GHA runner version to the latest (auto-generated)" \
   --body "" \
   --reviewer isegall-da,martinflorian-da,ray-roestenburg-da,mblaze-da
+
+echo "Done."