Switch to a GitHub Action

.eslintignore

@@ -0,0 +1,2 @@
+!.eslintrc.js
+/dist/

.eslintrc.js

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+"use strict";
+
+module.exports = {
+  env: {
+    es6: true,
+  },
+  extends: [
+    "plugin:unicorn/recommended",
+    "xo",
+    "xo-typescript",
+    "prettier",
+    "prettier/@typescript-eslint",
+  ],
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    ecmaVersion: 2018,
+    project: "tsconfig.json",
+    sourceType: "module",
+  },
+  plugins: ["sort-destructure-keys", "typescript-sort-keys", "unicorn"],
+  root: true,
+  rules: {
+    // @actions/github uses a lot of snake_case keys.
+    "@typescript-eslint/camelcase": "off",
+    // TypeScript is good at type inference and already requires types where they matter: exported symbols.
+    "@typescript-eslint/explicit-function-return-type": "off",
+    // We use sort-keys instead.
+    "@typescript-eslint/member-ordering": "off",
+    "arrow-body-style": "error",
+    // Forbid function declarations
+    "func-style": ["error", "expression", { allowArrowFunctions: true }],
+    // It's fine to use await in for loops instead of Promise.all to execute promises sequentially.
+    "no-await-in-loop": "off",
+    "no-console": "error",
+    // TypeScript already takes care of that. See https://github.com/bradzacher/eslint-plugin-typescript/issues/110.
+    "no-undef": "off",
+    "object-shorthand": [
+      "error",
+      "always",
+      { avoidExplicitReturnArrows: true },
+    ],
+    "sort-destructure-keys/sort-destructure-keys": [
+      "error",
+      { caseSensitive: false },
+    ],
+    "sort-keys": [
+      "error",
+      "asc",
+      { caseSensitive: false, minKeys: 2, natural: true },
+    ],
+    "typescript-sort-keys/interface": "error",
+    "typescript-sort-keys/string-enum": "error",
+    "unicorn/prevent-abbreviations": ["error", { whitelist: { args: true } }],
+  },
+};

.github/workflows/autosquash.yml

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+name: Autosquash
+on:
+  check_run:
+    types:
+      - completed
+  pull_request:
+    types:
+      - closed
+      - labeled
+  pull_request_review:
+    types:
+      - submitted
+  status: {}
+
+jobs:
+  autosquash:
+    name: Autosquash
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: tibdex/autosquash@v2
+        with:
+          github_token: ${{ secrets.AUTOSQUASH_TOKEN }}

.github/workflows/backport.yml

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+name: Backport
+on:
+  pull_request:
+    types:
+      - closed
+      - labeled
+
+jobs:
+  backport:
+    runs-on: ubuntu-18.04
+    name: Backport
+    steps:
+      - name: Backport
+        uses: tibdex/backport@v1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/publish.yml

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+name: Publish
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  publish:
+    name: Publish
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v1
+      - uses: dylanvann/[email protected]
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/test.yml

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+name: Test
+on:
+  push:
+    branches-ignore:
+      - master
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v1
+      - name: Install
+        run: yarn install --frozen-lockfile
+      - name: Build
+        run: yarn run build
+      - name: ESLint
+        run: yarn run eslint
+      - name: Prettier
+        run: yarn run check-prettier

.gitignore

@@ -1,4 +1,2 @@
-/.env
-/coverage/
-/node_modules/
-/reports/
+/dist
+/node_modules

README.md

@@ -1,37 +1,11 @@
-[![build status](https://img.shields.io/circleci/project/github/tibdex/backport.svg)](https://circleci.com/gh/tibdex/backport)
+Backport is a [JavaScript GitHub Action](https://help.github.com/en/articles/about-actions#javascript-actions) to backport a pull request by simply adding a label to it.
 
-# Goal
-
-Backport is a GitHub App, based on [Probot](https://probot.github.io/), to backport a pull request by simply adding a label to it. [Try it!](https://github.com/apps/backporting)
+It can backport [rebased and merged](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-request-merges#rebase-and-merge-your-pull-request-commits) pull requests with a single commit and [squashed and merged](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-request-merges#squash-and-merge-your-pull-request-commits) pull requests. It thus integrates well with [Autosquash](https://github.com/marketplace/actions/autosquash).
 
 # Usage
 
-1.  :electric_plug: Install the publicly hosted [Backport GitHub App](https://github.com/apps/backporting) on your repository.
+1.  :electric_plug: Add this [.github/workflows/backport.yml](.github/workflows/backport.yml) to your repository.
 2.  :speech_balloon: Let's say you want to backport a pull request on a branch named `production`. Then label it with `backport production`. (See [how to create labels](https://help.github.com/articles/creating-a-label/).)
 3.  :sparkles: That's it! When the pull request gets merged, it will be backported to the `production` branch. If the pull request cannot be backported, a comment explaining why will automatically be posted.
 
 _Note:_ multiple backport labels can be added. For example, if a pull request has the labels `backport staging` and `backport production` it will be backported to both branches: `staging` and `production`.
-
-## Demo
-
-![Backport demo](./assets/demo.gif)
-
-This pull request has two commits and targets the `development` branch. After labeling it with `backport production` and merging it, Backport automatically creates a pull request on the `production` branch by cherry-picking these two commits.
-
-# How it Works
-
-Backport relies on [`github-backport`](https://www.npmjs.com/package/github-backport) to perform all the required Git operations directly through the GitHub REST API instead of having to clone repositories on a server and executing Git CLI commands.
-
-`github-backport` is the :old_key: to being able to run Backport as a stateless, easy to maintain, and cheap to operate, GitHub App!
-
-## Which Permissions & Webhooks Is Backport Using?
-
-### Permissions
-
-- **Repository contents** _[read & write]_: because the backporting process requires creating commits and manipulating branches.
-- **Issues** _[read & write]_: to post comments when the backport process fails.
-- **Pull requests** _[read & write]_: to create new pull requests.
-
-### Webhooks
-
-- **Pull requests**: to detect when pull requests are merged or labeled.

action.yml

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+name: Backporting
+author: Thibault Derousseaux <[email protected]>
+description: Automatically backport PRs to other branches by simply labeling them.
+inputs:
+  github_token:
+    description: Token for the GitHub API.
+    required: true
+runs:
+  using: node12
+  main: dist/index.js
+branding:
+  icon: arrow-left-circle
+  color: purple