GitHub CI with Fly deploy

Ci.yml

name: Test & Deploy
on: push

jobs:
  test:
    name: Test
    runs-on: ubuntu-24.04
    steps:
      - uses: actions/checkout@v4
      - uses: erlef/setup-beam@v1
        with:
          version-type: strict
          version-file: .tool-versions
      - name: Cache deps
        id: cache-deps
        uses: actions/cache@v4
        env:
          cache-name: cache-elixir-deps
        with:
          path: deps
          key: ${{ runner.os }}-mix-${{ env.cache-name }}-${{ hashFiles('**/mix.lock') }}
          restore-keys: |
            ${{ runner.os }}-mix-${{ env.cache-name }}-

      # Step: Define how to cache the `_build` directory. After the first run,
      # this speeds up tests runs a lot. This includes not re-compiling our
      # project's downloaded deps every run.
      - name: Cache compiled build
        id: cache-build
        uses: actions/cache@v4
        env:
          cache-name: cache-compiled-build
        with:
          path: _build
          key: ${{ runner.os }}-mix-${{ env.cache-name }}-${{ hashFiles('**/mix.lock') }}
          restore-keys: |
            ${{ runner.os }}-mix-${{ env.cache-name }}-
            ${{ runner.os }}-mix-

      # Step: Conditionally bust the cache when job is re-run.
      # Sometimes, we may have issues with incremental builds that are fixed by
      # doing a full recompile. In order to not waste dev time on such trivial
      # issues (while also reaping the time savings of incremental builds for
      # *most* day-to-day development), force a full recompile only on builds
      # that are retried.
      - name: Clean to rule out incremental build as a source of flakiness
        if: github.run_attempt != '1'
        run: |
          mix deps.clean --all
          mix clean
        shell: sh
      - run: mix deps.get
      - run: mix gettext.extract --check-up-to-date
      - run: mix format --check-formatted
      - run: mix test

  deploy:
    name: Deploy
    needs: test
    runs-on: ubuntu-24.04
    environment: production
    if: github.ref == 'refs/heads/main'
    concurrency: deploy-group    # optional: ensure only one action runs at a time
    steps:
      - uses: actions/checkout@v4
      - uses: superfly/flyctl-actions/setup-flyctl@master
      - run: flyctl deploy --remote-only
        env:
          FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}