migrations.yml

name: Migrations

# Deploy runs `alembic upgrade head` against the database six production apps
# share, and nothing until now checked the migration graph. Alembic does not fail
# on a duplicate revision id — it warns and carries on, leaving two heads — so a
# green PR could take a broken graph straight to production.

on:
  pull_request:

env:
  # Opt JavaScript-based actions into Node.js 24 ahead of the 2026-06-02
  # forced switch. Remove once the runner default is Node 24.
  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: "true"

jobs:
  migrations:
    runs-on: ubuntu-latest

    services:
      postgres:
        image: postgres:17
        env:
          # No password at all, rather than a fake one: this container is reachable
          # only from this job, and a credential in the repo is a credential to scan,
          # rotate and mistake for a real one.
          POSTGRES_HOST_AUTH_METHOD: trust
        ports:
          - 5432:5432
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5

    env:
      JWT_SECRET_KEY: test-secret-for-ci-only
      DATABASE_URL: postgresql://postgres@localhost:5432/postgres

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Install uv
        uses: astral-sh/setup-uv@v4

      - name: Set up Python
        run: uv python install 3.11

      - name: Install dependencies
        run: uv sync --frozen --group dev

      - name: The graph has one head and no duplicate revision ids
        run: |
          set -euo pipefail
          # A duplicate revision id is only a UserWarning, and `alembic heads`
          # still exits 0 while printing two heads. Make the warning fatal.
          heads=$(PYTHONWARNINGS=error::UserWarning uv run alembic heads)
          echo "$heads"
          count=$(printf '%s\n' "$heads" | grep -c '(head)')
          if [ "$count" -ne 1 ]; then
            echo "::error::expected a single head, found $count — the migration graph has branched"
            exit 1
          fi

      - name: Upgrade and downgrade on a clean database
        run: |
          set -euo pipefail
          uv run alembic upgrade head
          # The newest migration has to undo exactly what it did: a downgrade that
          # leaves the schema dirty fails the next upgrade.
          uv run alembic downgrade -1
          uv run alembic upgrade head