Assign GitHub PR Reviewers by Code Ownership (Supabase + Slack)

Assign GitHub PR Reviewers Automatically—Using Code Ownership (Supabase + Slack)

This n8n workflow listens for GitHub pull request webhooks, determines which reviewers own the changed code, then requests the right GitHub reviewers and DMs them on Slack—balancing load using Supabase.

What this workflow does

• Receives PR webhooks via an n8n webhook endpoint when a pull_request event occurs.
• Filters PRs to continue only for newly opened, non-draft pull requests that are not authored by bots.
• Loads reviewer ownership data from Supabase, including:
  • GitHub username
  • Slack user ID
  • Owned path prefixes
  • last assigned time (last_assigned_at)
• Matches changed files to owned path prefixes, excludes the PR author, and selects candidates based on least recently assigned to evenly distribute review work.
• Requests reviewers on GitHub (up to a configured maximum) using the GitHub REST API.
• Notifies each selected reviewer in Slack with a direct message containing the PR title, author, and link.
• Updates Supabase by setting last_assigned_at so future assignments stay balanced.

Use cases

• Teams with clear ownership boundaries (e.g., frontend vs. backend) who want code-ownership-based PR review.
• SaaS operators reducing manual reviewer selection by automating GitHub reviewer assignment.
• On-call or distributed teams using Supabase to track reviewer coverage and rotation.

Technical details

• Integrations: GitHub (PR reviewer requests), Slack (DMs), Supabase (reviewer roster + load balancing).
• n8n workflow logic: if, set, code, no op, merge, and Slack-related steps.
• Setup basics: Configure a GitHub webhook, provide a GitHub personal access token with permission to request reviewers, and create/populate a Supabase reviewers table with the roster fields.