Initial update to CI

We wanted to try and speed up the CI tasks for the Rails Template.

This work introduces the same approach we took to save time on the DfE
Complete project.

We use Docker supplied actions to build the image and cache the layers
to the Github actions cache.

Subsequent jobs are set to use the layers from the cache which, in most
cases, gives us a nice speed boost.

We've split the jobs so they can be run in parallel, as we know the
image is the same for each job they all use the strategy.

We've kept the Shellcheck task separate as this code is not strictly
speaking the application code, so doesn't really need to be inside the
image.

.github/workflows/continuous-integration.yml

@@ -1,5 +1,7 @@
 # TODO: Enable GitHub Actions on the repository to test all pull requests
 # https://github.com/<org>/<repo>/actions
+name: CI Checks
+
 on:
   pull_request:
   push:
@@ -8,18 +10,129 @@ on:
       - develop
 
 jobs:
-  test:
+  build-and-cache:
+    name: Build and cache image
     runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v4
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      -
+        name: Build and cache image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          build-args: RAILS_ENV=test
+          push: false
+          tags: app_test:latest
+          cache-from: type=gha
+          cache-to: type=gha,mode=min
 
-    env:
-      RAILS_ENV: test
+  lint-and-format:
+    name: Linting and format application
+    runs-on: ubuntu-latest
+    needs: build-and-cache
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v4
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      -
+        name: Build and cache
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          build-args: |
+            RAILS_ENV=test
+          push: false
+          load: true
+          tags: app_test:latest
+          cache-from: type=gha
+      -
+        name: Run linters and formatters
+        run: |
+          docker run --rm app_test:latest /bin/bash -c "bundle exec standardrb -f simple && \
+            yarn run lint:js && \
+            yarn run lint:css && \
+            yarn run lint:format"
 
+  static-analysis:
+    name: Static analysis
+    runs-on: ubuntu-latest
+    needs: build-and-cache
     steps:
-      - name: Check out code
+      -
+        name: Checkout
         uses: actions/checkout@v4
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      -
+        name: Build and cache
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          build-args: |
+            RAILS_ENV=test
+          push: false
+          load: true
+          tags: app_test:latest
+          cache-from: type=gha
+      -
+        name: Run Brakeman
+        run: |
+          docker run --rm app_test:latest /bin/bash -c "bundle exec brakeman -o /dev/stdout"
 
-      - name: Build
-        run: script/ci/cibuild
+  specs:
+    name: Specs and coverage
+    runs-on: ubuntu-latest
+    needs: build-and-cache
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v4
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      -
+        name: Build and cache
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          build-args: |
+            RAILS_ENV=test
+          push: false
+          load: true
+          tags: app_test:latest
+          cache-from: type=gha
+      -
+        name: Run RSpec and Simplecov
+        run: |
+          docker compose -p complete-app -f docker-compose.ci.yml \
+            run --name app_test test /bin/bash -c "bin/rails spec"
+      -
+        name: Shutdown containers
+        run: docker compose -p app_test down && docker compose -p app_test rm
 
-      - name: Test
-        run: script/ci/test
+  shellcheck:
+    name: Linting scripts
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v4
+      -
+        name: Run Shellceck
+        run: |
+          for file in $(git ls-files script/*)
+          do shellcheck -x "$file"
+          done