chore: change if condition in workflow (#1567)

* chore: change if condition in workflow

* add head_ref

* add var

Author: JoeWang1127

.github/workflows/hermetic_library_generation.yaml

@@ -18,27 +18,37 @@ on:
   pull_request:
 
 env:
-  HEAD_REF: ${{ github.head_ref }}
   REPO_FULL_NAME: ${{ github.event.pull_request.head.repo.full_name }}
+  GITHUB_REPOSITORY: ${{ github.repository }}
 
 jobs:
   library_generation:
-    # skip pull requests coming from a forked repository
-    if: github.env.REPO_FULL_NAME == github.repository
     runs-on: ubuntu-latest
     steps:
+    - name: Determine whether the pull request comes from a fork
+      run: |
+        if [[ "${GITHUB_REPOSITORY}" != "${REPO_FULL_NAME}" ]]; then
+          echo "This PR comes from a fork. Skip library generation."
+          echo "SHOULD_RUN=false" >> $GITHUB_ENV
+        else
+          echo "SHOULD_RUN=true" >> $GITHUB_ENV
+        fi
     - uses: actions/checkout@v4
+      if: env.SHOULD_RUN == 'true'
       with:
         fetch-depth: 0
         token: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}
     - name: Generate changed libraries
+      if: env.SHOULD_RUN == 'true'
       shell: bash
       run: |
         set -ex
         [ -z "$(git config user.email)" ] && git config --global user.email "[email protected]"
         [ -z "$(git config user.name)" ] && git config --global user.name "cloud-java-bot"
         bash .github/scripts/hermetic_library_generation.sh \
-          --target_branch ${{ github.base_ref }} \
-          --current_branch $HEAD_REF
+          --target_branch "${BASE_REF}" \
+          --current_branch "${HEAD_REF}"
       env:
+        BASE_REF: ${{ github.base_ref }}
+        HEAD_REF: ${{ github.head_ref }}
         GH_TOKEN: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}