@netlify/config/src/env/git.js

Netlify config module

import { execa } from 'execa'

import { removeFalsy } from '../utils/remove_falsy.js'

// Retrieve git-related information for use in environment variables.
// git is optional and there might be not git repository.
// We purposely keep this decoupled from the git utility.
export const getGitEnv = async function (buildDir, branch) {
  const [COMMIT_REF, CACHED_COMMIT_REF] = await Promise.all([
    git(['rev-parse', 'HEAD'], buildDir),
    git(['rev-parse', 'HEAD^'], buildDir),
  ])
  const gitEnv = { BRANCH: branch, HEAD: branch, COMMIT_REF, CACHED_COMMIT_REF, PULL_REQUEST: 'false' }
  const gitEnvA = removeFalsy(gitEnv)
  return gitEnvA
}

const git = async function (args, cwd) {
  try {
    const { stdout } = await execa('git', args, { cwd })
    return stdout
  } catch {}
}