Remove the need for custom environment variables in GitHub actions

[agateau-gg]

Remove the need for custom environment variables in GitHub actions

Context

Our GitHub actions currently rely on the following environment variables:

• GITHUB_BASE_REF
• GITHUB_DEFAULT_BRANCH
• GITHUB_EVENT_NAME
• GITHUB_PUSH_BASE_SHA
• GITHUB_PUSH_BEFORE_SHA
• GITHUB_SHA

Their names are a bit deceiving though: not all of them are defined in GitHub CI environment. GITHUB_DEFAULT_BRANCH, GITHUB_PUSH_BASE_SHA and GITHUB_PUSH_BEFORE_SHA are not. These 3 variables must be defined by all users of our actions using the env: key, like this:

name: GitGuardian scan

on: [push, pull_request]

jobs:
  scanning:
    name: GitGuardian scan
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          fetch-depth: 0 # fetch all history so multiple commits can be scanned
      - name: GitGuardian scan
        uses: GitGuardian/[email protected]
        env:
          GITHUB_PUSH_BEFORE_SHA: ${{ github.event.before }}
          GITHUB_PUSH_BASE_SHA: ${{ github.event.base }}
          GITHUB_DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
          GITGUARDIAN_API_KEY: ${{ secrets.GITGUARDIAN_API_KEY }}

Goal

The goal of this issue is to remove the need for these 3 variables. The variables initialize themselves from the GitHub event object. This object is serialized as a .json file whose path is in GITHUB_EVENT_PATH. This means we can read it and initialize our variables from it.

Definition of Done

• Our GitHub action code no longer requires our users to define GITHUB_PUSH_BEFORE_SHA, GITHUB_PUSH_BASE_SHA or GITHUB_DEFAULT_BRANCH;
• For consistency, it would be good to read all variables from the .json file;
• The action documentation has been updated accordingly. Note: this documentation update must only be published after the changes have been released!

[GG-HH]

This seems related to #687 (eventually, one being a subset of the other), should we merge those ?

[agateau-gg]

Oh right, I missed #687 🤦🏻. Going to close this one and add the Definition of Done to 687.