Add automated PR reviewer rotation system

gursewak1997 · gursewak1997 · commit 551a0cc4ea24 · 2025-08-06T11:09:59.000-07:00
- Add GitHub Action workflow for automatic reviewer assignment
- Create Python script that reads reviewers from MAINTAINERS.md
- Implement 3-week sprint-based rotation cycle
- Preserve existing reviewer assignments (manual/GitHub auto)
- Add configuration for start date and rotation cycle
diff --git a/.github/auto-review-config.yml b/.github/auto-review-config.yml
@@ -0,0 +1,6 @@
+# Auto-reviewer configuration
+# Start date for the rotation cycle (YYYY-MM-DD format)
+start_date: "2025-08-04"
+
+# Rotation cycle in weeks
+rotation_cycle_weeks: 3
diff --git a/.github/scripts/assign_reviewer.py b/.github/scripts/assign_reviewer.py
@@ -0,0 +1,270 @@
+#!/usr/bin/env python3
+"""
+Auto-reviewer assignment script for GitHub PRs.
+Rotates through a list of reviewers based on a weekly cycle.
+Automatically reads reviewers from MAINTAINERS.md
+"""
+
+import os
+import sys
+import yaml
+import subprocess
+import re
+from datetime import datetime, timezone
+from typing import List, Optional, TypedDict
+
+
+class RotationInfo(TypedDict):
+    start_date: Optional[datetime]
+    rotation_cycle_weeks: int
+    weeks_since_start: float
+    before_start: bool
+    error: Optional[str]
+
+
+class SprintInfo(TypedDict):
+    sprint_number: int
+    week_in_sprint: int
+    total_weeks: int
+    before_start: Optional[bool]
+
+
+def load_config(config_path: str) -> dict:
+    """Load the reviewer configuration from YAML file."""
+    try:
+        with open(config_path, 'r') as f:
+            return yaml.safe_load(f)
+    except FileNotFoundError:
+        print(f"Error: Configuration file {config_path} not found", file=sys.stderr)
+        sys.exit(1)
+    except yaml.YAMLError as e:
+        print(f"Error parsing YAML configuration: {e}", file=sys.stderr)
+        sys.exit(1)
+
+
+def extract_reviewers_from_maintainers() -> List[str]:
+    """Extract GitHub usernames from MAINTAINERS.md file by parsing the table structure."""
+    maintainers_path = os.environ.get("MAINTAINERS_PATH", 'MAINTAINERS.md')
+    reviewers = []
+    
+    try:
+        with open(maintainers_path, 'r') as f:
+            content = f.read()
+        
+        lines = content.splitlines()
+        github_id_column_index = None
+        in_table = False
+        
+        for line in lines:
+            line = line.strip()
+            
+            # Skip empty lines
+            if not line:
+                continue
+            
+            # Look for table header to find GitHub ID column
+            if line.startswith('|') and 'GitHub ID' in line:
+                in_table = True
+                columns = [col.strip() for col in line.split('|')[1:-1]]  # Remove empty first/last elements
+                try:
+                    github_id_column_index = columns.index('GitHub ID')
+                except ValueError:
+                    print("Error: Could not find 'GitHub ID' column in MAINTAINERS.md table")
+                    sys.exit(1)
+                continue
+            
+            # Skip separator line (|---|---|...)
+            if in_table and line.startswith('|') and '---' in line:
+                continue
+            
+            # Process table data rows
+            if in_table and line.startswith('|') and github_id_column_index is not None:
+                columns = [col.strip() for col in line.split('|')[1:-1]]
+                if len(columns) > github_id_column_index:
+                    github_id_cell = columns[github_id_column_index]
+                    match = re.search(r'\[([^\]]+)\]\(https://github\.com/[^)]+\)', github_id_cell)
+                    if match:
+                        username = match.group(1)
+                        if username and username not in reviewers:
+                            reviewers.append(username)
+            
+            # Stop parsing when we hit the end of the table
+            if in_table and not line.startswith('|'):
+                break
+
+        if reviewers:
+            print(f"Found {len(reviewers)} reviewers from MAINTAINERS.md: {', '.join(reviewers)}")
+        else:
+            print("Warning: No GitHub usernames found in MAINTAINERS.md")
+            
+    except FileNotFoundError:
+        print(f"Error: MAINTAINERS.md file not found")
+        sys.exit(1)
+    except IOError as e:
+        print(f"Error reading MAINTAINERS.md: {e}")
+        sys.exit(1)
+    
+    return reviewers
+
+
+def calculate_rotation_info(config: dict) -> RotationInfo:
+    """Calculate rotation information from config (helper function)."""
+    start_date_str = config.get('start_date')
+    rotation_cycle_weeks = config.get('rotation_cycle_weeks', 3)
+    
+    if not start_date_str:
+        return {
+            "start_date": None,
+            "rotation_cycle_weeks": rotation_cycle_weeks,
+            "weeks_since_start": 0,
+            "before_start": False,
+            "error": "No start_date configured"
+        }
+    
+    try:
+        start_date = datetime.strptime(start_date_str, "%Y-%m-%d").replace(tzinfo=timezone.utc)
+        current_date = datetime.now(timezone.utc)
+        weeks_since_start = (current_date - start_date).total_seconds() / (7 * 24 * 3600)
+        
+        return {
+            "start_date": start_date,
+            "rotation_cycle_weeks": rotation_cycle_weeks,
+            "weeks_since_start": weeks_since_start,
+            "before_start": weeks_since_start < 0,
+            "error": None
+        }
+    except ValueError:
+        return {
+            "start_date": None,
+            "rotation_cycle_weeks": rotation_cycle_weeks,
+            "weeks_since_start": 0,
+            "before_start": False,
+            "error": f"Invalid start_date format: {start_date_str}"
+        }
+
+
+def get_current_sprint_info(rotation_info: RotationInfo) -> SprintInfo:
+    """Calculate current sprint information."""
+    
+    if rotation_info["before_start"]:
+        return {
+            "sprint_number": 1,
+            "week_in_sprint": 1,
+            "total_weeks": 0,
+            "before_start": True
+        }
+    
+    weeks_since_start = rotation_info["weeks_since_start"]
+    rotation_cycle_weeks = rotation_info["rotation_cycle_weeks"]
+    
+    sprint_number = int(weeks_since_start // rotation_cycle_weeks) + 1
+    week_in_sprint = int(weeks_since_start % rotation_cycle_weeks) + 1
+    
+    return {
+        "sprint_number": sprint_number,
+        "week_in_sprint": week_in_sprint,
+        "total_weeks": int(weeks_since_start)
+    }
+
+
+def calculate_current_reviewer(reviewers: List[str], rotation_info: RotationInfo) -> Optional[str]:
+    """Calculate the current reviewer based on the rotation schedule."""
+    if not reviewers:
+        print("Error: No reviewers found")
+        return None
+    
+    if rotation_info["before_start"]:
+        print(f"Warning: Current date is before start date. Using first reviewer.")
+        return reviewers[0]
+    
+    # Calculate total weeks since start and map to reviewer
+    # Each reviewer gets rotation_cycle_weeks weeks, then we cycle to the next
+    total_weeks = int(rotation_info["weeks_since_start"])
+    rotation_cycle_weeks = rotation_info["rotation_cycle_weeks"]
+    reviewer_index = (total_weeks // rotation_cycle_weeks) % len(reviewers)
+    
+    return reviewers[reviewer_index]
+
+
+def get_existing_reviewers(pr_number: str) -> List[str]:
+    """Get list of reviewers already assigned to the PR."""
+    try:
+        result = subprocess.run(
+            ['gh', 'pr', 'view', pr_number, '--json', 'reviewRequests', '--jq', '.reviewRequests[].login'],
+            capture_output=True, text=True, check=True
+        )
+        return result.stdout.strip().split('\n') if result.stdout.strip() else []
+    except FileNotFoundError:
+        print("Error: 'gh' command not found. Is the GitHub CLI installed and in the PATH?")
+        sys.exit(1)
+    except subprocess.CalledProcessError as e:
+        print(f"Error: Could not fetch existing reviewers for PR {pr_number}: {e.stderr}", file=sys.stderr)
+        sys.exit(1)
+
+
+def assign_reviewer(pr_number: str, reviewer: str) -> bool:
+    """Assign a reviewer to the PR using GitHub CLI."""
+    try:
+        subprocess.run(
+            ['gh', 'pr', 'edit', pr_number, '--add-reviewer', reviewer],
+            check=True, capture_output=True, text=True
+        )
+        print(f"Successfully assigned reviewer {reviewer} to PR {pr_number}")
+        return True
+    except FileNotFoundError:
+        print("Error: 'gh' command not found. Is the GitHub CLI installed and in the PATH?")
+        sys.exit(1)
+    except subprocess.CalledProcessError as e:
+        print(f"Error assigning reviewer {reviewer} to PR {pr_number}: {e.stderr}", file=sys.stderr)
+        sys.exit(1)
+
+
+def main():
+    """Main function to handle reviewer assignment."""
+    # Get PR number from environment variable
+    pr_number = os.environ.get('PR_NUMBER')
+    if not pr_number:
+        print("Error: PR_NUMBER environment variable not set")
+        sys.exit(1)
+    
+    # Load configuration (for start_date and rotation_cycle_weeks)
+    config_path = os.environ.get('AUTO_REVIEW_CONFIG_PATH', '.github/auto-review-config.yml')
+    config = load_config(config_path)
+    
+    # Extract reviewers from MAINTAINERS.md
+    reviewers = extract_reviewers_from_maintainers()
+    if not reviewers:
+        print("Error: No reviewers found in MAINTAINERS.md")
+        sys.exit(1)
+    
+    # Calculate rotation information once
+    rotation_info = calculate_rotation_info(config)
+    if rotation_info['error']:
+        print(f"Error in configuration: {rotation_info['error']}", file=sys.stderr)
+        sys.exit(1)
+    
+    # Get sprint information
+    sprint_info = get_current_sprint_info(rotation_info)
+    print(f"Current sprint: {sprint_info['sprint_number']}, week: {sprint_info['week_in_sprint']}")
+    
+    # Calculate current reviewer
+    current_reviewer = calculate_current_reviewer(reviewers, rotation_info)
+    if not current_reviewer:
+        print("Error: Could not calculate current reviewer")
+        sys.exit(1)
+    
+    print(f"Assigned reviewer for this week: {current_reviewer}")
+    
+    # Get existing reviewers
+    existing_reviewers = get_existing_reviewers(pr_number)
+    
+    # Check if current reviewer is already assigned
+    if current_reviewer in existing_reviewers:
+        print(f"Reviewer {current_reviewer} is already assigned to PR {pr_number}")
+        return
+    
+    # Assign the current reviewer
+    assign_reviewer(pr_number, current_reviewer)
+
+if __name__ == "__main__":
+    main()
diff --git a/.github/workflows/auto-review.yml b/.github/workflows/auto-review.yml
@@ -0,0 +1,33 @@
+name: Auto Assign Reviewer
+
+on:
+  pull_request:
+    types: [opened, ready_for_review]
+
+jobs:
+  assign-reviewer:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        
+      - name: Setup Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.11'
+          
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pyyaml
+          
+      - name: Authenticate with GitHub
+        run: |
+          echo "${{ secrets.GITHUB_TOKEN }}" | gh auth login --with-token
+          
+      - name: Assign reviewer
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          python .github/scripts/assign_reviewer.py
