ci: Fix image caching and apply other improvements #1756

1. 
   hebasto commented at 9:57 pm on October 3, 2025: member

   This PR fixes an issue where only the latest image cache was available.

   For other minor improvements, see the individual commit messages.

2. hebasto force-pushed on Oct 4, 2025
3. real-or-random added the label ci on Oct 13, 2025
4. real-or-random added the label bug on Oct 13, 2025
5. 
   real-or-random commented at 1:26 pm on October 13, 2025: contributor

   Relevant docs: https://docs.docker.com/build/cache/backends/gha/
6. in .github/actions/run-in-docker-action/action.yml:25 in fb9856a140 outdated

   19       id: main_builder
   20       continue-on-error: true
   21       with:
   22         context: .
   23         file: ${{ inputs.dockerfile }}
   24-        tags: ${{ inputs.tag }}
   

   ---

   ---

   

   real-or-random commented at 1:27 pm on October 13, 2025:

   Even after looking at the docs, I’m not sure what the tags parameter is actually supposed to do. Did you figure this out?

   ---

   

   hebasto commented at 1:48 pm on October 13, 2025:

   It’s meant to be used when exporting a built image to a registry.
7. in .github/actions/run-in-docker-action/action.yml:24 in fb9856a140 outdated

   22         context: .
   23         file: ${{ inputs.dockerfile }}
   24-        tags: ${{ inputs.tag }}
   25         load: true
   26-        cache-from: type=gha
   27+        cache-from: type=gha,scope=${{ runner.arch }}
   

   ---

   ---

   

   real-or-random commented at 1:29 pm on October 13, 2025:

   Would it be a good idea to add {{input.tag}} here (and maybe rename tag to scope)?

   ---

   

   hebasto commented at 1:50 pm on October 13, 2025:

   I don’t think so. Tags are not used for caching.

   ---

   

   real-or-random commented at 1:54 pm on October 13, 2025:

   I think we’re talking past each other. (But sorry, my message was very unclear.) My suggestion is to add an input parameter to the run-in-docker-action that is used as a prefix to scope, i.e., the caller sets the scope.

   In our case, the caller could then set scope=ci-image-${{ runner.arch }} or something like this.

   ---

   

   hebasto commented at 2:09 pm on October 13, 2025:

   I see. Reworked.
8. in .github/actions/run-in-docker-action/action.yml:7 in fb9856a140 outdated

    2@@ -3,10 +3,8 @@ description: 'Run a command in a Docker container, while passing explicitly set
    3 inputs:
    4   dockerfile:
    5     description: 'A Dockerfile that defines an image'
    6-    required: true
    7-  tag:
    8-    description: 'A tag of an image'
    9-    required: true
   10+    required: false
   11+    default: ./ci/linux-debian.Dockerfile
   

   ---

   ---

   

   real-or-random commented at 1:31 pm on October 13, 2025:

   I’m not sure if this is a reasonable default. I mean, yes, this is what we always use. But currently, this action is not specific to libsecp256k1 at all, and I think it would be nice to keep it that way.

   ---

   

   hebasto commented at 1:52 pm on October 13, 2025:

   It seems unlikely that this action would be reused elsewhere.

   ---

   

   hebasto commented at 2:57 pm on October 13, 2025:

   The controversial commit has been dropped.
9. in ci/linux-debian.Dockerfile:3 in fb9856a140

   0@@ -1,5 +1,7 @@
   1 FROM debian:stable-slim
   2 
   3+ENV DEBIAN_FRONTEND=noninteractive
   

   ---

   ---

   

   real-or-random commented at 1:33 pm on October 13, 2025:

   I think this is not a good idea because the Dockerfile can also be used interactively on a developer’s machine. See https://serverfault.com/a/797318

   ---

   

   hebasto commented at 2:01 pm on October 13, 2025:

   Thanks! Reworked.
10. hebasto force-pushed on Oct 13, 2025
11. ci: Add `scope` parameter to `cache-{to,from}` options

    This change fixes an issue where only the latest image cache was
    available.

    122014edb3
12. hebasto force-pushed on Oct 13, 2025
13. ci: Drop `tags` input for `docker/build-push-action`

    The `tags` input is unused for caching.

    b2a95a420f
14. ci: Bump `docker/build-push-action` version

    See https://github.com/docker/build-push-action/releases.

    70ae177ca0
15. ci: Set `DEBIAN_FRONTEND=noninteractive`

    This suppresses `debconf: unable to initialize frontend: ...` warnings.

    f163c35897
16. hebasto force-pushed on Oct 13, 2025
17. 
    hebasto commented at 2:57 pm on October 13, 2025: member

    @real-or-random

    Thank you for the review! Your feedback has been addressed.

Contributors
hebasto real-or-random

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bug ci