feat: add retag-release workflow to add a vX.Y.Z tag for our GitHub Action (#545)

* feat: add retag-release workflow to add a vX.Y.Z tag for our GitHub Action

* Update .github/workflows/retag-release.yaml

Co-authored-by: Kanad Gupta <kgupta@umn.edu>

* refactor: move code out of YAML and into bin/ script

* fix: lint fixes

Co-authored-by: Kanad Gupta <kgupta@umn.edu>

Author: RyanGWU82

.github/workflows/retag-release.yaml

@@ -0,0 +1,20 @@
+# This script adds a "vX.Y.Z" tag to every new release.
+#
+# Our releases are tagged like "1.2.3" but we want people to be able to write
+# GitHub Action workflows to say "uses: readmeio/readme@v1.2.3" because that's
+# the usual GitHub convention.
+
+name: retag-release
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  retag-release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/github-script@v6
+        with:
+          script: require('./bin/retag-release.js')(github, context);

bin/retag-release.js

@@ -0,0 +1,42 @@
+/* eslint-disable no-console */
+module.exports = async (github, context) => {
+  const { owner, repo } = context.repo;
+  const oldTag = context.payload.release.tag_name;
+  if (!oldTag.match(/^[0-9]+\.[0-9]+\.[0-9]+$/)) {
+    console.log('Not retagging this release: This script will only retag releases that use');
+    console.log(`semantic versioning, like "1.2.3", but this release's tag is "${oldTag}".`);
+    return {};
+  }
+  const newTag = `v${oldTag}`;
+  console.log(`Retagging release "${oldTag}" as "${newTag}".`);
+
+  const oldRef = await github.rest.git.getRef({
+    owner,
+    repo,
+    ref: `tags/${oldTag}`,
+  });
+  if (oldRef.status < 200 || oldRef.status >= 400) {
+    console.log(oldRef);
+    throw new Error(`GitHub API call returned HTTP status code ${oldRef.status}`);
+  }
+  const sha = oldRef.data.object.sha;
+  console.log(`Found tag "${oldTag}"; commit hash is ${sha}`);
+
+  console.log(`Creating tag "${newTag}" pointing to commit hash ${sha}...`);
+  const newRef = await github.rest.git.createRef({
+    owner,
+    repo,
+    ref: `refs/tags/${newTag}`,
+    sha,
+  });
+  if (newRef.status < 200 || newRef.status >= 400) {
+    console.log(newRef);
+    throw new Error(`GitHub API call returned HTTP status code ${newRef.status}`);
+  }
+  console.log('Successfully retagged this release.');
+  return {
+    original_tag: oldTag,
+    new_tag: newTag,
+    sha,
+  };
+};