github/workflows: Enable Docker layer caching between builds

.dockerignore

@@ -1,13 +1,27 @@
-# Ignore the Docker files themselves to avoid that all layers are invalidated if
-# the Docker files are changed during development.
+# Ignore Docker-related files to avoid the cache being invalidated if the files are changed during development.
+.batect/
 .dockerignore
 Dockerfile*
 scripts/docker_*.sh
 
-# Ignore the Jenkinsfile to avoid that all layers are invalidated if the
-# Jenkinsfile is changed during development.
+# Ignore GitHub configuration to avoid the cache being invalidated if the files are changed during development.
+.github/
+
+# Ignore the Jenkinsfile to avoid the cache being invalidated if the file is changed during development.
 integrations/jenkins/Jenkinsfile
 
+# Ignore miscellaneous top-level configuration files that do not have an impact on ORT's build.
+.codecov.yml
+.commitlintrc.yml
+.editorconfig
+.jitpack.yml
+.lift.toml
+.mailmap
+.ort.yml
+mlc_config.json
+qodana.yml
+renovate.json
+
 # Ignore Git entries.
 .git/
 .gitignore

.github/workflows/build-and-test.yml

@@ -136,6 +136,9 @@ jobs:
         flags: funTest-non-docker
   funTest-docker:
     runs-on: ubuntu-22.04
+    permissions:
+      contents: read
+      packages: write
     steps:
     - name: Checkout Repository
       uses: actions/checkout@v3
@@ -148,6 +151,33 @@ jobs:
         java-version: 17
     - name: Restore Gradle cache entries
       uses: gradle/gradle-build-action@v2
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v2
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+    - name: Setup Docker Buildx
+      uses: docker/setup-buildx-action@v2
+    - name: Build and push the Docker image
+      uses: docker/build-push-action@v4
+      with:
+        build-args: USER_ID=1001
+        context: .
+        cache-from: type=registry,ref=ort:buildcache
+        cache-to: type=registry,ref=ort:buildcache,mode=max
+        push: true
+        tags: ort:pr
+    - name: Build and load the Docker image
+      uses: docker/build-push-action@v4
+      with:
+        build-args: USER_ID=1001
+        context: .
+        cache-from: type=registry,ref=ort:buildcache
+        cache-to: type=registry,ref=ort:buildcache,mode=max
+        load: true
+    - name: Build Docker image manually
+      run: DOCKER_BUILDKIT=1 docker build --build-arg USER_ID=1001 .
     - name: Validate Batect wrapper scripts
       uses: batect/batect-wrapper-validation-action@v0
     - name: Run functional tests that do require external tools