Automatic Repo Tagging GitHub Action

This GitHub Action automatically tags your repository with a tag determined by a shell command, and you have control of the shell command. By default, the shell command is cat VERSION, so this action looks at the contents of a VERSION file in the repository when determining what the tag should be. Some notes:

1. By default, the final tag has a v prepended to the results of the shell command. Suppose the shell command is cat VERSION and the contents of the VERSION file is 1.2.3-rc1, then the repo will be tagged with v1.2.3-rc1 when this action is run. This can be disabled by setting PREPEND_V environment variable to false.
2. If the repo is already tagged with the version then no attempt is made to tag the repo and nothing happens.

Below are some example shell commands that determine the version.

Getting the version from a file

This action allows the user to customize the command used to get the name of the tag. This is done by setting a VERSION_COMMAND environment variable. Some languages allow you (or require you) to set the version in some config file. I've included some example main.yamls with an appropriate VERSION_COMMAND.

Elixir

For elixir, the main.yaml below can be used to read the version defined in mix.exs (assuming the version key is on it's own line in the project section of mix.exs):

name: Creates a tag for the repo
  push:
    branches:
      - master 
jobs:
  build:
    name: Tag repo using mix.exs file
    runs-on: ubuntu-20.04    
    steps:
    - name: Checkout master
      uses: actions/checkout@master
    - name: Tagging repo using version specified in mix.exs
      uses: djordon/[email protected]
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        VERSION_COMMAND: >
          cat mix.exs
            | grep --line-buffer "version: "
            | grep --extended-regexp --only-matching "\"[-0-9\.\+a-zA-Z]+\""
            | grep --extended-regexp --only-matching "[-0-9\.\+a-zA-Z]+"

Rust

For rust, you can do something like the following:

...
    - name: Tagging repo using version specified in Cargo.toml
      uses: djordon/[email protected]
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        VERSION_COMMAND: >
          cat Cargo.toml
            | grep --extended-regexp "^version ="
            | grep --extended-regexp --only-matching "[0-9]+\.[0-9]+.[0-9]+[-\.\+a-zA-Z0-9]*"
            | head --lines=1