How to use output from GitHub Action with `--output`?

[MPV]

Expected behavior

I'd like to be able to run the GitHub Action for container-diff using the --output flag, so I can pass/use the output from the command in other

Actual behavior

Using the action (as in the steps below) triggers:

container-diff diff daemon://my.domain/my/repo:latest daemon://my.domain/my/repo:3401858ca10b2df5cbdb4341b75e4b9051e89722 --type=file  --output="container-diff-file.txt

...which gives:

cat: container-diff-file.txt: No such file or directory
Error: Process completed with exit code 1.

Information

• container-diff version: v0.17.0 (0695621)
• Operating system: Linux (via GitHub Actions)

Steps to reproduce the behavior

1. Run the GitHub Action for container-diff with the --output flag, as per below:

For example:

      - name: Run container-diff analyze
        if: github.event_name == 'pull_request'
        uses: GoogleContainerTools/container-diff/actions@0695621c48497a11a893a8fc0af7965c674123da
        with:
          command: analyze          
          args: daemon://${{ env.IMAGE }}:${{ github.sha }} --output="container-diff-analyze.txt"

      - name: Publish container-diff analyze
        run: |
          echo '## `container-diff analyze`' > "${GITHUB_STEP_SUMMARY}"
          echo '```' >> "${GITHUB_STEP_SUMMARY}"
          cat container-diff-analyze.txt >> "${GITHUB_STEP_SUMMARY}"
          echo '```' >> "${GITHUB_STEP_SUMMARY}"

...or...

      - name: Pull latest for comparison
        if: github.event_name == 'pull_request'
        run: docker pull ${{ env.IMAGE }}:latest

      - name: Run container-diff diff file
        if: github.event_name == 'pull_request'
        uses: GoogleContainerTools/container-diff/actions@0695621c48497a11a893a8fc0af7965c674123da
        with:
          command: diff          
          args: daemon://${{ env.IMAGE }}:latest daemon://${{ env.IMAGE }}:${{ github.sha }} --type=file  --output="container-diff-file.txt"

Other info/context

Back in this PR:

• Update GitHub Action for Modern Syntax #402

...we added a Dockerfile for running container-diff, which may be a contributing factor to the problem and hiding the complexity/errors of using container-diff like this. It could also just be that I'm not yet understanding what's causing the issue just yet, happy to learn why this kind of issue might occur.

[MPV]

I'm trying variants of this, but I haven't yet succeeded.

For example by trying to write to a file in ${GITHUB_WORKSPACE}, I just get:

      - name: Run container-diff analyze
        if: github.event_name == 'pull_request'
        uses: GoogleContainerTools/container-diff/actions@0695621c48497a11a893a8fc0af7965c674123da
        with:
          command: analyze          
          args: daemon://${{ env.IMAGE }}:${{ github.sha }} --output="${GITHUB_WORKSPACE}/container-diff-analyze.txt"

container-diff diff daemon://my.domain/my/repo:latest daemon://my.domain/my/repo:3401858ca10b2df5cbdb4341b75e4b9051e89722 --type=file  --output="${GITHUB_WORKSPACE}/container-diff-analyze.txt"
time="2023-12-15T09:53:30Z" level=error msg="invalid argument"
time="2023-12-[15](https://github.com/my.org/my-repo/actions/runs/7220505570/job/19673561383#step:14:16)T09:53:30Z" level=error msg="invalid argument"

[MPV]

Never mind, I got this working now using ./ (--output=./container-diff-analyze.txt), as I saw in the README now:

• https://github.com/GoogleContainerTools/container-diff/blob/master/actions/README.md