Version 1.45.0 Has The new_tag Output Return As Empty

[Zozman]

Issue

On action version 1.45.0, the new_tag output is returned as an empty string.

Example

Action Code

     - name: Bump version and push tag
        uses: anothrNick/[email protected]
        id: tag
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          DEFAULT_BUMP: patch

      - name: Login to GitHub Container Registry
        uses: docker/login-action@v2
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build & push Docker image to GitHub Container Registry
        uses: docker/build-push-action@v3
        with:
          push: true
          platforms: linux/amd64,linux/arm64
          tags: |
            ghcr.io/user/repo:latest
            ghcr.io/user/repo:${{ steps.tag.outputs.new_tag }}

Result

/usr/bin/docker buildx build --iidfile /tmp/docker-build-push-zz6BYw/iidfile --platform linux/amd64,linux/arm64 --secret id=GIT_AUTH_TOKEN,src=/tmp/ --tag ghcr.io/user/repo:latest --tag ghcr.io/user/repo: --metadata-file /tmp/docker-build-push/metadata-file --push https://github.com/user/repogit#fakehash
ERROR: invalid tag "ghcr.io/user/repo:": invalid reference format
Error: buildx failed with: ERROR: invalid tag "ghcr.io/user/tag:": invalid reference format

As shown in this example, ${{ steps.tag.outputs.new_tag }} ends up being an empty string so the tag ghcr.io/user/repo: ends up invalid as it's a docker tag with no actual tag on it.

Workaround

Downgrading to 1.44.0 fixes the issue.

[sammcj]

yikes! OK another test case needs to be added for this!

Going to revert in #183