feat(CODEOWNERS): Workaround for PR reviewers (#13662)

A while ago we made this change
#8868 so that we can have
codeowner review requirement enforced, but still have a reference on who
owns what.
This prevented the codeowners from becoming a blocker especially when we
have teams working across time zones.

But it became a bit inconvenient as the owners of files don't get tagged
in PR automatically and informed for review.
This PR is meant to fix that.

The new workflow file will be triggered on all PRs, identify all the
modified files in the PR, and cross match with all the commented lines
in CODEOWNERS files, if there's any match it will add the owners as
reviewer automatically.

Note: Approvals from reviewers added by this PR will not be required
before PR can be merged, this is more of an informational and making
sure proper teams are involved and informed on changes.

Author: Jeffreyhung

.github/workflows/codeowner_assignment.yaml

@@ -0,0 +1,121 @@
+name: Codeowner assignment
+
+on: [pull_request]
+
+jobs:
+  codeowner_assignment:
+    name: Codeowner assignment
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+
+    steps:
+      - uses: actions/checkout@v4
+      
+      - uses: actions/[email protected]
+        id: token
+        with:
+          app-id: ${{ vars.CODEOWNER_ASSIGNMENT_GITHUB_APP_ID }}
+          private-key: ${{ secrets.CODEOWNER_ASSIGNMENT_PRI_KEY }}
+          owner: ${{ github.repository_owner }}
+          repositories: |
+            sentry-docs
+
+      - name: Parse CODEOWNERS and assign reviewers
+        id: assign-reviewers
+        env:
+          PR_NUMBER: ${{ github.event.number }}
+          GH_TOKEN: ${{ steps.token.outputs.token }}
+        run: |
+          # locate CODEOWNERS file exists
+          if [[ -f .github/CODEOWNERS ]]; then
+            codeowner_path=".github/CODEOWNERS"
+          elif [[ -f CODEOWNERS ]]; then
+            codeowner_path="CODEOWNERS"
+          else
+            echo "CODEOWNERS file not found, skipping."
+            exit 0
+          fi
+
+          # Get changed files in the PR
+          git fetch origin ${{ github.event.pull_request.base.ref }} \
+            ${{ github.event.pull_request.head.ref }}
+          CHANGED_FILES=$(git diff --name-only origin/${{ github.event.pull_request.base.ref }} \
+            origin/${{ github.event.pull_request.head.ref }})
+
+          echo "----------------------------------------"
+          echo "Changed files:"
+          echo "$CHANGED_FILES" | tr ' ' '\n' | sed 's/^/- /'
+          echo "----------------------------------------"
+
+          # Parse CODEOWNERS and find commented lines
+          # Add newline to the end of the file if it doesn't have one, otherwise sed will not read the last line
+          sed -i -e '$a\' $codeowner_path
+          
+          while read -r LINE; do
+            # Skip lines that are not commented, GitHub will take care of un-commented lines
+            if [[ ! "$LINE" =~ ^# ]]; then continue; fi
+
+            # Extract pattern and reviewer from the commented line
+            PATTERN=$(echo "$LINE" | sed -E 's/^#\s*([^@]+).*$/\1/' | xargs)
+            # Capture both individual users and GitHub teams reviewers that have "/" in the name
+            REVIEWERS=$(echo "$LINE" | grep -o "@[a-zA-Z0-9_-]\+\(/[a-zA-Z0-9_-]\+\)\?" | tr '\n' ' ' | xargs)
+
+            # Skip if no reviewers found
+            if [[ -z "$REVIEWERS" ]]; then
+              continue
+            fi
+
+            # Convert pattern to a regex for matching
+            REGEX_PATTERN=$(echo "$PATTERN" | sed -e 's/\./\\./g' -e 's/\*/.*/g' -e 's/\?/./g' -e 's|^/||')
+            
+            # Match changed files to the pattern
+            for FILE in $CHANGED_FILES; do
+              # For glob patterns(e.g. "**/"), use a different matching approach
+              if [[ "$PATTERN" == *"*"* ]]; then
+                # Special handling for **/ pattern
+                if [[ "$PATTERN" == "**/"* ]]; then
+                  # Get the filename part after **/
+                  FILENAME=${PATTERN#**/}
+                  # Match either the filename directly or with any path prefix
+                  if [[ "$FILE" == "$FILENAME" ]] || [[ "$FILE" == */"$FILENAME" ]]; then
+                    echo "File $FILE matches glob pattern $PATTERN"
+                    # Assign each reviewer
+                    for REVIEWER in $REVIEWERS; do
+                      # Remove @ symbol from reviewer name
+                      REVIEWER_NAME=${REVIEWER#@}
+                      echo " - Assigning $REVIEWER_NAME to review changes in $FILE"
+                      gh pr edit $PR_NUMBER --add-reviewer "$REVIEWER_NAME"
+                    done
+                  fi
+                else
+                  # Convert other glob patterns to regex for matching
+                  GLOB_PATTERN=$(echo "$PATTERN" | sed -e 's/\./\\./g' -e 's/\*/.*/g' -e 's/\?/./g')
+                  if [[ "$FILE" =~ $GLOB_PATTERN ]]; then
+                    echo "File $FILE matches glob pattern $PATTERN"
+                    # Assign each reviewer
+                    for REVIEWER in $REVIEWERS; do
+                      # Remove @ symbol from reviewer name
+                      REVIEWER_NAME=${REVIEWER#@}
+                      echo " - Assigning $REVIEWER_NAME to review changes in $FILE"
+                      gh pr edit $PR_NUMBER --add-reviewer "$REVIEWER_NAME"
+                    done
+                  fi
+                fi
+              else
+                # Original directory matching logic
+                if [[ "$FILE" == ${REGEX_PATTERN}* ]]; then
+                  echo "File $FILE matches pattern $PATTERN"
+                  # Assign each reviewer
+                  for REVIEWER in $REVIEWERS; do
+                    # Remove @ symbol from reviewer name
+                    REVIEWER_NAME=${REVIEWER#@}
+                    echo " - Assigning $REVIEWER_NAME to review changes in $FILE"
+                    gh pr edit $PR_NUMBER --add-reviewer "$REVIEWER_NAME"
+                  done
+                fi
+              fi
+            done
+          done < $codeowner_path
+