ci: push container images to github registry in addition to dockerhub

it's good to have multiple container registries, in case one decides to not
be welcoming anymore to open-source projects

.github/workflows/docker-latest.yml

@@ -10,16 +10,27 @@ jobs:
         uses: docker/setup-qemu-action@v1
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1
+
       - name: Login to DockerHub
         uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
+      -
+        name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Build and push
         id: docker_build
         uses: docker/build-push-action@v2
         with:
           push: true
-          tags: shaarli/shaarli:latest
+          tags: |
+            shaarli/shaarli:latest
+            ghcr.io/shaarli/shaarli:latest
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}

.github/workflows/docker-tags.yml

@@ -16,16 +16,27 @@ jobs:
         uses: docker/setup-qemu-action@v1
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1
+
       - name: Login to DockerHub
         uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
+      -
+        name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Build and push
         id: docker_build
         uses: docker/build-push-action@v2
         with:
           push: true
-          tags: shaarli/shaarli:${{ env.REF }}
+          tags: |
+            shaarli/shaarli:${{ env.REF }}
+            ghcr.io/shaarli/shaarli:${{ env.REF }}
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}