fix(env): make git_branch fallback to github_ref

.env.defaults

@@ -1,4 +1,3 @@
-GIT_BRANCH=master
 GIT_HOST=github.com
 GIT_COMMIT_MESSAGE=chore(actions): empty commit for contribution graph
 GIT_SSH_COMMAND=ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no

.github/CONTRIBUTING.md

@@ -31,6 +31,7 @@ Thanks for considering a contribution to this project! 🙏
      * Make sure to check the **Repo** boxes.
      * Note that the personal access token has more permissions than the `GITHUB_TOKEN` provided by the Actions runner. Read more about this [here](https://help.github.com/en/actions/configuring-and-managing-workflows/authenticating-with-the-github_token#permissions-for-the-github_token).
    * `GIT_EMAIL`: Set this to [an email associated with your GitHub account](https://github.com/settings/emails).
+   * `GIT_BRANCH`: Set this to `master`.
 1. Make sure your Docker daemon is running.
 
 ### Running 👟

README.md

@@ -45,7 +45,7 @@
 
 If you change your mind about these commits later, you can delete the repository and they'll disappear from your contribution graph.
 
-### Push a commit to master once a day 🍺
+### Push a commit to GitHub once a day 🍺
 
 ```yml
 # .github/workflows/main.yml
@@ -66,16 +66,14 @@ jobs:
 
 If you need help with cron job syntax, [crontab guru](https://crontab.guru/) is a great resource.
 
-### Backfill a year of commits whenever you push to master 🍻
+### Backfill a year of commits whenever you push to GitHub 🍻
 
 This rolls a pseudorandom number generator between 1 and 5 (inclusive) to determine how many commits to make per-day.
 
 ```yml
 # .github/workflows/main.yml
 
-on:
-  push:
-    branches: [ master ]
+on: push
 
 jobs:
   backfill-commits:
@@ -103,7 +101,7 @@ Keep reading for more cool stuff like:
 |-----------------------|--------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------|-----------|
 | `GITHUB_TOKEN`        | Allows this GitHub Action to make commits for you. Simply pass in `${{ secrets.GITHUB_TOKEN }}`. [Read more](#github_token-).  |                                                       |    🟩     |
 | `GIT_EMAIL`           | An email address associated with your GitHub account. Without this, contributions won't show up. [Read more](#git_email-).     |                                                       |    🟩     |
-| `GIT_BRANCH`          | Must either be the default branch (usually `master`) or `gh-pages` for contributions to show up.                               | `master`                                              |           |
+| `GIT_BRANCH`          | Must either be the default branch or `gh-pages` for contributions to show up.                                                  | The branch that triggered this Github Action          |           |
 | `GIT_COMMIT_MESSAGE`  | The message to use for commits made by this GitHub Action.                                                                     | `chore(actions): empty commit for contribution graph` |           |
 | `ORIGIN_TIMESTAMP`    | The unix timestamp to start commits on. If you set `MAX_DAYS` greater than 1, commits will be made on days prior to this time. | The current timestamp                                 |           |
 | `MAX_DAYS`            | The maximum integer number of days to commit on. If you want to backfill a year of commits, set this to `365`.                 | `1`                                                   |           |

src/index.js

@@ -9,6 +9,7 @@ import git from 'simple-git/promise';
 import {getRandomInt} from './random';
 
 const env = autoParse({
+  GIT_BRANCH: process.env.GIT_BRANCH || process.env.GITHUB_REF.replace(/^refs\/heads\//, ''),
   ORIGIN_TIMESTAMP: process.env.ORIGIN_TIMESTAMP || getUnixTime(new Date()),
   ...dotenv.load({errorOnMissing: true, includeProcessEnv: true}),
 });