Fixed entrypoint for github actions

[mcasperson]

Github actions can take advantage of the GitVersion docker image, but they ignore the working directory, so the entrypoint ["dotnet", "GitVersion.dll"] fails to load. Pointing to the absolute path for the DLL solves the issue.

[arturcic]

Looks good to me! Thanks for the contribution 👍. Could you please provide details on how use use the Github actions with GitVersion docker image? Just curious.

[gep13]

@mcasperson @arturcic I would be curious about how you are doing this as well. Would a dedicated GitHub Action for GitVersion make sense?

[mcasperson]

Getting values out of a Github action seems a little clunky at the moment, but you can save the version to a file and consume that in another step like this:

name: Python package

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v1
    - name: Get Git Version
      uses: docker://gittools/gitversion:5.0.2-linux-centos-7-netcoreapp2.2
      with:
        args: /github/workspace /nofetch /exec /bin/sh /execargs "-c \"echo $GitVersion_MajorMinorPatch > /github/workspace/version.txt\""

The directory /github/workspace is shared across actions, so the version.txt file will be available for subsequent steps.

Versioning with GitHub actions is a huge hole at the moment. Almost every CI action would benefit from being able to access a sensible incrementing version, and GitVersion is the only thing that I have seen (beyond date based versions) that can fill this.

[mcasperson]

https://octopus.com/blog/versioning-with-github-actions describes how we have taken advantage of this feature.

[arturcic]

Great article @mcasperson! A quick question, have you considered using
/showvariable FullSemVer as argument instead of calling bash to output the env variable?

[mcasperson]

@arturcic The challenge with GitHub actions is sharing the result with subsequent jobs. GA doesn't capture the output of a command, so for that version value to be made available it has to be saved in a file because the filesystem is shared between GA jobs. Calling bash via /exec looked like the easiest way to use an unmodified docker image and generate a file with the version contents.