Add GitHub Action to publish Docker image

This workflow builds a Spring Boot application into a Docker image and publishes it to Docker Hub on push to master or new releases.

Author: noobdevsam

.github/workflows/publish-docker.yml

@@ -0,0 +1,61 @@
+# This GitHub Action workflow builds the Spring Boot application into a Docker image
+# and publishes it to Docker Hub.
+#
+# It triggers on two events:
+# 1. A push to the 'master' branch, which tags the image as 'latest'.
+# 2. Publishing a new release, which tags the image with the release version (e.g., 'v1.0.0').
+
+name: Publish Docker Image to Docker Hub
+
+on:
+  push:
+    branches: [ "master" ]
+  release:
+    types: [ published ]
+
+jobs:
+  build-and-publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 25
+        uses: actions/setup-java@v4
+        with:
+          java-version: '25'
+          distribution: 'liberica' # Liberica provides builds for JDK 25
+
+      - name: Extract metadata for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ secrets.DOCKERHUB_USERNAME }}/${{ github.event.repository.name }}
+          tags: |
+            # type=schedule
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            # Set 'latest' tag when pushing to the master branch
+            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/master' }}
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        run: |
+          # The 'spring-boot:build-image' goal uses Paketo Buildpacks to create a Docker image.
+          # The 'pom.xml' is already configured with the image name.
+          # We enable publishing and pass the generated tags from the metadata step.
+          ./mvnw spring-boot:build-image \
+            -DskipTests \
+            -Dspring-boot.build-image.publish=true \
+            -Dspring-boot.build-image.imageName=${{ steps.meta.outputs.tags }}