Improve Docker and CI/CD configuration with best practices

- Dockerfile: Add non-root user, healthcheck, optimized layer caching
- docker-compose.yml: Add healthchecks, data volumes, networking, better configuration
- CI/CD: Add multi-platform builds, image testing, multiple tags, metadata
- .dockerignore: Comprehensive exclusions for faster builds

These improvements enhance security, reliability, and maintainability
following Docker and Spring Boot best practices.

Signed-off-by: Bhavesh Khandelwal <bhaveshkhandelwal1232@gmail.com>

.github/workflows/container-build.yml

@@ -6,15 +6,16 @@ on:
   pull_request:
     branches: [ main ]
 
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
 jobs:
   build:
     runs-on: ubuntu-latest
     permissions:
       contents: read
       packages: write
-    env:
-      REGISTRY: ghcr.io
-      IMAGE_NAME: ${{ github.repository }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -32,6 +33,19 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha,prefix={{branch}}-
+            type=raw,value=latest,enable={{is_default_branch}}
+
       - name: Log in to GitHub Container Registry
         if: github.event_name == 'push' && github.ref == 'refs/heads/main'
         uses: docker/login-action@v3
@@ -45,7 +59,24 @@ jobs:
         with:
           context: .
           push: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
-          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha
           cache-to: type=gha,mode=max
+          platforms: linux/amd64,linux/arm64
+
+      - name: Test Docker image
+        if: github.event_name == 'pull_request'
+        run: |
+          docker build -t spring-petclinic-test .
+          docker run -d --name petclinic-test -p 8080:8080 \
+            -e SPRING_PROFILES_ACTIVE=h2 \
+            spring-petclinic-test
+          echo "Waiting for application to start..."
+          sleep 45
+          echo "Testing health endpoint..."
+          curl -f http://localhost:8080/actuator/health || exit 1
+          echo "Health check passed!"
+          docker stop petclinic-test
+          docker rm petclinic-test