#github-action #version #deployment #generate #outputs #docker #repository

bin+lib ghaction_version_gen

Generate various version options as github action outputs

12 releases

0.14.0 Feb 18, 2024
0.13.6 Dec 26, 2023
0.13.5 Oct 18, 2023
0.13.2 Mar 30, 2023
0.13.0 Nov 29, 2022

#356 in Command line utilities

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MIT license

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ghaction-version-gen is a docker github action that outputs a version number for you to use in a deploy action.

There are many ways to generate version information for a repository. They usually involve processing GITHUB_REF in some way, maybe using even using github-script.

This repository is also an example of how to create a docker github action that compiles a rust entrypoint in a container and then moves it to a second, minimal container.


The following are the primary outputs of this action, usually the ones used for versioning:

  • version_tagged: for repositories that should only deploy on tags, it's defined if the github event was a push of a tag.

    The output itself is the tag, with the optional v stripped.

    This output can be overriden via the OVERRIDE_VERSION_TAGGED environment variable.

  • version_commit: for repositories that deploy on tags and on all commits to master or main. It's defined if the github event was a push of a tag or of one of those branches.

    The output itself is the the tag that was pushed, or the most recent tag on the branch followed by the distance between the branch and the tag (always with the v stripped).

    This output can be overriden via the OVERRIDE_VERSION_COMMIT environment variable.

  • version_docker_ci: for repositories that deploy to hub.docker continuously. If the commit was pushed to master or main, the variable has the value "latest"; if a tag was pushed, it has the tag (v stripped); otherwise, it has the value "null" as a string. This last case allows us to always use the variable as the version for the build-push-action, which doesn't like empty strings.

    This output can be overriden via the OVERRIDE_VERSION_DOCKER_CI environment variable.

You can these variables in action in the Examples section.

This github action is also able to check if a project-specific version matches with the latest tags. At the moment, only rust's Cargo.toml file is checked. If there's a mismatch and a new tag is being pushed, the action fails.

Secondary outputs

These are the secondary outputs that might be useful for debugging or as alternative versioning schemes:

  • is_push: if the github event was identified, "true" if the event was a push or "false" otherwise.
  • is_tag: if the github ref was identified, "true" if the ref is a tag, false otherwise.
  • is_main: "true" if the github ref was for a branch named main or master.
  • is_push_tag: "true" if a tag was pushed.
  • is_push_main: "true" if main or master were pushed.
  • commit: the hash of the commit.
  • commit_main: the hash of the commit where the main/master branch is.
  • is_main_here: "true" if the main/master branch coincides with the current commit.
  • git_describe_tags: the output of git describe --tags
  • tag_latest: the most recent tag.
  • distance: the distance between the current commit and tag_latest.
  • tag_distance: tag_latest-distance
  • tag_head: the tag on HEAD, if there's a tag on HEAD (does not depend on the gitub event).
  • dash_distance: - prepended to distance
  • tag_latest_ltrimv: tag_latest without the optional leading v.
  • tag_head_ltrimv: tag_head without the optionsl leading v, if tag_head was defined.
  • rust_crate_version: the version in Cargo.toml if it exists.
  • version_tagged: tag_head_ltrimv if is_push_tag.
  • version_commit: tag_head_ltrimv if is_push_tag or tag_distance_ltrimv if is_push_main.
  • version_docker_ci: "latest" if is_push_main, tag_head_ltrimv if is_push_tag.
  • version_mismatch: if there's a version mismatch between the contents of a file and the latest tag, this is the error message. This also appears as a github action "error".


version_tagged and version_commit

Using version_tagged and version_commit is quite simple:

    runs-on: ubuntu-latest
      - uses: actions/checkout@v2
      - id: version
        uses: docker://lpenz/ghaction-version-gen:0.13.4
      - name: deploy
        uses: <deploy action>
        if: steps.version.outputs.version_tagged != ''
          version: ${{ steps.version.outputs.version_tagged }}

That gets the deploy step to run only when a tag is pushed, and sets version to the tag with the optional v prefix stripped.

If we replace version_tagged with version_commit in the example above, we get an additional behavior: version_commit is also defined when main or master are pushed, and it assumes the value of the last tag (v stripped) suffixed with - and the distance of the pushed commit to that tag. This should be used in projects that want to deploy every time main is pushed.


The version_docker_ci variable was designed to work with the docker's build-push-action. It should be used in projects where we would use want to deploy from tags and from main/master, but we want main/master to be identified as latest in docker hub.

This is how it's used:

    runs-on: ubuntu-latest
      - uses: actions/checkout@v2
      - id: version
        uses: docker://lpenz/ghaction-version-gen:0.13.4
      - uses: docker/login-action@v1
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      - uses: docker/build-push-action@v2
          push: ${{ steps.version.outputs.version_docker_ci != 'null' }}
          tags: ${{ github.repository }}:${{ steps.version.outputs.version_docker_ci }}

Note that we don't make the build-push-action step conditional because we always want to build the container. Instead, we make push conditional, by checking that version_docker_ci is not null. We use null instead of the empty string as a workaround, because the action doesn't let us use an empty string as the version in tags.


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