Add action to require milestones on PRs

Signed-off-by: Sebastian Malton <sebastian@malton.name>

.github/actions/require-milestone/Dockerfile

@@ -0,0 +1,11 @@
+# Container image that runs your code
+FROM node:14-alpine
+
+COPY package*.json /home/action/
+COPY entrypoint.js /home/action/entrypoint.js
+
+WORKDIR /home/action
+RUN npm ci
+
+# Code file to execute when the docker container starts up (`entrypoint.js`)
+ENTRYPOINT ["node", "/home/action/entrypoint.js"]

.github/actions/require-milestone/action.yml

@@ -0,0 +1,9 @@
+name: 'require-milestone'
+description: 'A GitHub Action to require a milestone is placed on a PR to merge it'
+author: 'Sebastian Malton'
+branding:
+  icon: 'command'
+  color: 'blue'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'

.github/actions/require-milestone/entrypoint.js

@@ -0,0 +1,34 @@
+/**
+ * Copyright (c) 2021 OpenLens Authors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+const { Toolkit } = require("actions-toolkit");
+
+Toolkit.run(async tools => {
+  if (!tools.context.payload.pull_request.milestone) {
+    tools.exit.failure(
+      [
+        "Milestone error. All PRs must have a milestone set to be merged.",
+        "Bug fixes can be targeted at the next patch milestone after the feature they fix is targetted.",
+        "All other PRs should be targetted at the next minor milestone."
+      ].join("\n\n"),
+    );
+  }
+});

.github/actions/require-milestone/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "require-milestone",
+  "version": "1.0.0",
+  "description": "A GitHub action to require that PRs have milestones set before being merged",
+  "main": "entrypoint.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "MIT",
+  "dependencies": {
+    "actions-toolkit": "^6.0.1"
+  }
+}

.github/workflows/require-milestone.yml

@@ -0,0 +1,12 @@
+name: Require Milestone
+
+on:
+  pull_request:
+    types: [opened, edited]
+
+jobs:
+  require_milestone:
+    runs-on: ubuntu-latest
+    steps:
+      # Drafts your next Release notes as Pull Requests are merged into "master"
+      - uses: ./.github/actions/require-milestone