build(infra): also push Docker images to ghcr.io

.github/workflows/build-infra-dockers.yaml

@@ -12,6 +12,10 @@ env:
   BUILD_USER: docker
   BUILD_HOST: github.syncthing.net
 
+permissions:
+  contents: read
+  packages: write
+
 jobs:
   docker-syncthing:
     name: Build and push Docker images
@@ -41,6 +45,13 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+      - name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Build binaries
         run: |
           for arch in arm64 amd64; do
@@ -53,13 +64,13 @@ jobs:
 
       - name: Set Docker tags (all branches)
         run: |
-          tags=syncthing/${{ matrix.pkg }}:${{ github.sha }}
+          tags=docker.io/syncthing/${{ matrix.pkg }}:${{ github.sha }},ghcr.io/syncthing/infra/${{ matrix.pkg }}:${{ github.sha }}
           echo "TAGS=$tags" >> $GITHUB_ENV
 
       - name: Set Docker tags (latest)
         if: github.ref == 'refs/heads/infrastructure'
         run: |
-          tags=syncthing/${{ matrix.pkg }}:latest,${{ env.TAGS }}
+          tags=docker.io/syncthing/${{ matrix.pkg }}:latest,ghcr.io/syncthing/infra/${{ matrix.pkg }}:latest,${{ env.TAGS }}
           echo "TAGS=$tags" >> $GITHUB_ENV
 
       - name: Build and push