Adding a label containing an octothorpe (#) incorrectly results in the label being stripped #451

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1. tomdoel

   added

   status/triage

   on Aug 21, 2024
2. crazy-max commented on Aug 22, 2024

   

   crazy-max

   on Aug 22, 2024

   Last edited by crazy-max

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   Yes this relates to #172 to enable comments for these inputs:

   metadata-action/src/context.ts

   Lines 24 to 28 in 60a0d34

   	images: Util.getInputList('images', {ignoreComma: true, comment: '#'}),
   	tags: Util.getInputList('tags', {ignoreComma: true, comment: '#'}),
   	flavor: Util.getInputList('flavor', {ignoreComma: true, comment: '#'}),
   	labels: Util.getInputList('labels', {ignoreComma: true, comment: '#'}),
   	annotations: Util.getInputList('annotations', {ignoreComma: true, comment: '#'}),

   Disabling comments would be a breaking change though so you can either escape this char or we could introduce an env var to disable comments.
3. crazy-max

   added

   status/needs-investigation

   and removed

   status/triage

   on Aug 22, 2024
4. tomdoel commented on Aug 23, 2024

   

   tomdoel

   on Aug 23, 2024

   Last edited by tomdoel

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   Thanks for the update.

   So as I understand it, the underlying issue was that YAML does not allow comments in multi-line scalar inputs:

   -
   labels: |
     # This is not a valid YAML comment; it is part of the labels input
     mylabel=foo#bar

   So in order to allow for comments in the labels input, metadata-action calls getInputList, which uses csv-parse to remove the comments. But this also removes parts of the labels containing #.

   I don't think it's possible to escape #, but I can force quotes around the label. csv-parse will remove the quotes and accept the whole label instead of interpreting the comment. So for example, this works:

   - name: Docker meta
     id: meta
     uses: docker/metadata-action@v5
     with:
       images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
       labels: "
         \"mylabel=foo#bar\""

   However this feels a little fragile as it relies on the implementation detail that csv-parse is being used to process the inputs.

   So instead I am using the following workaround where I append the custom label to the push action instead of the meta action:

   - name: Docker meta
     id: meta
     uses: docker/metadata-action@v5
     with:
       images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
   
   - name: Build and push Docker image
     id: push
     uses: docker/build-push-action@v6
     with:
       context: .
       push: true
       tags: ${{ steps.meta.outputs.tags }}
       labels: |
         ${{ steps.meta.outputs.labels }}
         mylabel=foo#bar
5. theanurin

   marked tags input breaks when using # in Git tag or regex #546 as a duplicate of this issue on Aug 20, 2025
6. theanurin commented on Aug 20, 2025

   

   theanurin

   on Aug 20, 2025

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   @crazy-max
   I want to invest time into the issue...
   Do you have an idea for right solution?

   May be something like this:

   - name: Docker meta
     id: meta
     uses: docker/metadata-action@v5
     with:
       comment: "//"
       labels: |
         mylabel=foo#bar // this is a comment
7. crazy-max

   added this to the v6 milestone on Nov 4, 2025
8. crazy-max commented on Nov 4, 2025

   

   crazy-max

   on Nov 4, 2025

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   Added to v6 milestone
9. crazy-max commented on Mar 5, 2026

   

   crazy-max

   on Mar 5, 2026

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   Opened #607

   Can be tested with:

           - name: Docker meta
             id: meta
             uses: crazy-max/docker-metadata-action@allow-comments
             with:
               images: acme/myapp
               labels: |
                 # full line comment allowed
                 org.opencontainers.image.revision=${{ github.sha }}#source
10. crazy-max

    added

    kind/enhancement

    and removed

    status/needs-investigation

    on Mar 5, 2026
11. tonistiigi

    closed this as completedin #607on Mar 5, 2026