Merge pull request #33156 from backstage/freben/dependabot-dedupe

ci: dedupe yarn.lock in Dependabot PR workflow

.github/workflows/sync_dependabot-changesets.yml

@@ -21,11 +21,47 @@ jobs:
           fetch-depth: 2
           ref: ${{ github.head_ref }}
           token: ${{ secrets.GH_SERVICE_ACCOUNT_TOKEN }}
+      - name: Verify Dependabot branch
+        id: verify
+        run: |
+          if git branch --show-current | grep -q '^dependabot/'; then
+            echo "is_dependabot=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "Not a dependabot branch, skipping"
+            echo "is_dependabot=false" >> "$GITHUB_OUTPUT"
+          fi
       - name: Configure Git
+        if: steps.verify.outputs.is_dependabot == 'true'
         run: |
           git config --global user.email noreply@backstage.io
           git config --global user.name 'Github changeset workflow'
+      - name: Setup Node
+        if: steps.verify.outputs.is_dependabot == 'true'
+        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        with:
+          node-version: 22.x
+      - name: Dedupe lockfiles
+        if: steps.verify.outputs.is_dependabot == 'true'
+        id: dedupe
+        run: |
+          corepack enable
+          changed=false
+
+          for dir in . docs-ui microsite; do
+            if [ "$dir" = "." ]; then lockfile=yarn.lock; else lockfile="$dir/yarn.lock"; fi
+            if git diff --name-only HEAD~1 | grep -q "^${lockfile}$"; then
+              yarn --cwd "$dir" dedupe
+              if ! git diff --quiet "$lockfile"; then
+                git add "$lockfile"
+                changed=true
+              fi
+            fi
+          done
+
+          echo "changed=$changed" >> "$GITHUB_OUTPUT"
       - name: Generate changeset
+        if: steps.verify.outputs.is_dependabot == 'true'
+        id: changeset
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         with:
           script: |
@@ -50,12 +86,6 @@ jobs:
               await fs.writeFile(fileName, body);
             }
 
-            const branch = await exec.getExecOutput('git branch --show-current');
-            if (!branch.stdout.startsWith('dependabot/')) {
-              console.log('Not a dependabot branch, skipping');
-              return;
-            }
-
             const diffOutput = await exec.getExecOutput('git diff --name-only HEAD~1');
             const diffFiles = diffOutput.stdout.split('\n');
 
@@ -79,5 +109,9 @@ jobs:
             const { stdout: commitMessage } = await exec.getExecOutput('git show --pretty=format:%s -s HEAD');
             await createChangeset(fileName, commitMessage, packageNames);
             await exec.exec('git', ['add', fileName]);
-            await exec.exec('git commit -C HEAD --amend --no-edit');
-            await exec.exec('git push --force');
+            core.setOutput('changed', 'true');
+      - name: Commit and push
+        if: steps.verify.outputs.is_dependabot == 'true' && (steps.dedupe.outputs.changed == 'true' || steps.changeset.outputs.changed == 'true')
+        run: |
+          git commit -C HEAD --amend --no-edit
+          git push --force