add GHA CD via Dockerhub

.github/workflows/docker-image.yml

@@ -0,0 +1,47 @@
+name: Docker Image CD
+
+on:
+  push:
+    branches: [ "master" ]
+  workflow_dispatch:
+    inputs:
+      docker-tagname:
+        description: Tag name of the Docker image
+        default: 'ocrd/sbb_binarization'
+
+env:
+  DOCKER_TAGNAME: ${{ github.evenv.inputs.docker-tagname || 'ocrd/sbb_binarization' }}
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+
+    steps:
+    - uses: actions/checkout@v4
+    - # Activate cache export feature to reduce build time of image
+      name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v2
+    - name: Build the Docker image
+      run: make docker DOCKER_TAG=${{ env.DOCKER_TAGNAME }}
+    - name: Login to Dockerhub
+      uses: docker/login-action@v2
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_PASSWORD }}
+    - name: Push image to Dockerhub
+      run: docker push ${{ env.DOCKER_TAGNAME }}
+    - name: Alias the Docker image for GHCR
+      run: docker tag ${{ env.DOCKER_TAGNAME }} ghcr.io/${{ github.repository }}
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v2
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+    - name: Push image to Github Container Registry
+      run: docker push ghcr.io/${{ github.repository }}