use branch name for image tag, latest for main branch

Author: RoguedBear

.github/workflows/publish-image.yml

@@ -22,14 +22,22 @@ jobs:
       - uses: actions/checkout@v3
 
       # https://github.community/t/github-actions-repository-name-must-be-lowercase/184924
-      - name: downcase REPO
+      - name: downcase REPO & set branch/image tag name
         run: |
           echo "REPO_LC=${GITHUB_REPOSITORY,,}" >>${GITHUB_ENV}
+          export "BRANCH=${GITHUB_REF##*/}"
+          if [ $BRANCH == "main" ] || [ $BRANCH == "master" ]; then
+            echo "TAG=latest" >> ${GITHUB_ENV};
+          else  
+            echo "TAG=${BRANCH}" >> ${GITHUB_ENV};
+          fi
+
       # https://github.com/marketplace/actions/push-to-ghcr
       - name: Build and publish a Docker image for ${{ github.repository }}
         uses: macbre/push-to-ghcr@master
         with:
           image_name: ${REPO_LC}-backend
           github_token: ${{ secrets.GITHUB_TOKEN }}
+          tags: ${TAG}
           # optionally push to the Docker Hub (docker.io)
           # docker_io_token: ${{ secrets.DOCKER_IO_ACCESS_TOKEN }}  # see https://hub.docker.com/settings/security