Rely on "git log" to pick the latest commit that has changes in relevant packages

Author: alco

.github/workflows/ensure_sync_service_image.yml

@@ -4,7 +4,7 @@ on:
   workflow_call:
     inputs:
       tag:
-        required: true
+        required: false
         type: string
     outputs:
       image:
@@ -45,6 +45,13 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Get the latest commit SHA that has touched files in either packages/electric-telemetry or packages/sync-service
+        if: ${{ if !env.TAG }}
+        run: |
+          echo "TAG=$(
+            git log -1 --format='%H' -- electric-telemetry/ sync-service/{config, lib, rel, mix.*, package.json}
+          )" >> $GITHUB_ENV
+
       - name: Check if image tag already exists
         id: exists
         run: |

.github/workflows/ts_tests.yml

@@ -60,22 +60,8 @@ jobs:
       - run: pnpm -r --filter "$(jq '.name' -r package.json)^..." build
       - run: pnpm run typecheck
 
-  image_tag:
-    name: Derive the image tag for sync-service from the package source code
-    runs-on: ubuntu-latest
-    outputs:
-      tag: ${{ steps.hash.outputs.tag }}
-    steps:
-      - uses: actions/checkout@v4
-      - run: |
-          echo "tag=${{ hashFiles('packages/sync-service/mix.lock', 'packages/electric-telemetry/mix.lock') }}" >> $GITHUB_OUTPUT
-        id: hash
-
   ensure_sync_service_image:
-    needs: image_tag
     uses: ./.github/workflows/ensure_sync_service_image.yml
-    with:
-      tag: ${{ needs.image_tag.outputs.tag }}
 
   build_and_test_packages:
     name: 'Test ${{ matrix.package_dir }} w/ sync-service'