I could figure out how to actually pull this off on my own.

Description

Feature that enforces segregation of duties by checking the APPROVER or CODEOWNER file and ensuring that no committer can approve or merge their own code.

Create a workflow file in your repository (e.g., .github/workflows/enforce_sod.yml) with the following content:

name: Enforce Segregation of Duties

on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  enforce_sod:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout code
      uses: actions/checkout@v2

    - name: Set up Node.js
      uses: actions/setup-node@v2
      with:
        node-version: '14'

    - name: Install jq and yq
      run: |
        sudo apt-get update
        sudo apt-get install -y jq
        sudo snap install yq

    - name: Run Segregation of Duties Check
      id: sod_check
      run: |
        APPROVER_FILE=".github/approvers.yml"
        COMMITTERS=$(jq -r '.commits | .[].author.username' $GITHUB_EVENT_PATH | sort | uniq)
        PRIMARY_APPROVERS=$(yq '.approvers[] | select(.number == 0) | .username' $APPROVER_FILE)
        SECONDARY_APPROVERS=$(yq '.approvers[] | select(.number == 1) | .username' $APPROVER_FILE)

        echo "Committers: $COMMITTERS"
        echo "Primary Approvers: $PRIMARY_APPROVERS"
        echo "Secondary Approvers: $SECONDARY_APPROVERS"

        for approver in $PRIMARY_APPROVERS; do
          if [[ ! " $COMMITTERS " =~ " $approver " ]]; then
            echo "Found primary approver: $approver"
            exit 0
          fi
        done

        for approver in $SECONDARY_APPROVERS; do
          if [[ ! " $COMMITTERS " =~ " $approver " ]]; then
            echo "Found secondary approver: $approver"
            exit 0
          fi
        done

        echo "No eligible approver found"
        exit 1
    env:
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Inputs - GITHUB_TOKEN: - The GitHub token for authentication (required).

APPROVER

The APPROVER file should follow this format:

approvers:
  - username: "username1"
    number: 1
  - username: "username2"
    number: 0
  - username: "username3"
    number: 0
  - username: "username4"
    number: 0
  - username: "username5"
    number: 1
  - username: "username6"
    number: 1

Hierarchy

Users assigned 0 are Primary APPROVER.
Users assigned 1 are Secondary APPROVER.

Action Logic

The action follows these steps to enforce segregation of duties:

1. Identify Committers and Approvers:

The action first identifies all committers (users who have made commits) and approvers (users who are requested to review the pull request).

2. Remove Ineligible Approvers:

If any approver has also committed code to the pull request, they are marked as ineligible for that PR.

3. Find Eligible Approver:

The action then searches for a new approver in the APPROVER file. It first checks the Primary APPROVER (users assigned 0). If all Primary APPROVER have committed code and are thus ineligible, the action moves on to check the Secondary APPROVER (users assigned 1).

4. Assign New Approver:

The first eligible user found (who has not committed code to the pull request) is marked as an eligible approver.

Example

Let's say the action encounters the following scenario:

@username4 cannot approve the pull request because they have at least one commit as part of the PR.
The action then checks the next Primary APPROVER: @username2 (has at least one commit as part of the PR).
Then, @username3 (has at least one commit as part of the PR).
All Primary APPROVER are ineligible to approve the pull request because they have committed code.

The action then moves to the Secondary APPROVER:

@username1 is checked and found eligible (no commits in the PR).

Therefore, @username1 is assigned as the new approver.

approvers:
  - username: "username1"
    number: 1
  - username: "username2"
    number: 0
  - username: "username3"
    number: 0
  - username: "username4"
    number: 0
  - username: "username5"
    number: 1
  - username: "username6"
    number: 1

@username2, @username3, and @username4 are Primary APPROVER (assigned 0).
@username1, @username5, and @username6 are Secondary APPROVER (assigned 1).

gagoar / use-herald-action

[FEATURE REQUEST] Segregation of Duties (SOD): Enforces segregation of duties by checking a APPROVER CODEOWNER file #546