chore: automate publishing on new Git tags (puppeteer#6536)

Issues: puppeteer#6482

.github/workflows/publish-on-tag.yml

@@ -0,0 +1,30 @@
+name: publish-on-tag
+
+on:
+  push:
+    tags:
+    - '*'
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Install dependencies
+        run: npm install
+      - name: Build
+        run: npm run build
+      - name: Publish puppeteer
+        env:
+          NPM_TOKEN: ${{secrets.NPM_TOKEN_PUPPETEER}}
+        run: |
+          npm config set '//wombat-dressing-room.appspot.com/:_authToken' '${NPM_TOKEN}'
+          npm publish
+      - name: Publish puppeteer-core
+        env:
+          NPM_TOKEN: ${{secrets.NPM_TOKEN_PUPPETEER_CORE}}
+        run: |
+          utils/prepare_puppeteer_core.js
+          npm config set '//wombat-dressing-room.appspot.com/:_authToken' '${NPM_TOKEN}'
+          npm publish

.npmrc

@@ -0,0 +1,2 @@
+registry=https://wombat-dressing-room.appspot.com/
+access=public

CONTRIBUTING.md

@@ -286,17 +286,8 @@ Releasing to npm consists of the following phases:
     7. Once merged, publish the release notes using [GitHub's “draft new release tag” option](https://github.com/puppeteer/puppeteer/releases/new).
         - **NOTE**: tag names are prefixed with `'v'`, e.g. for version `1.4.0` the tag is `v1.4.0`.
         - For the “raw notes” section, use `git log --pretty="%h - %s" v2.0.0..HEAD`.
-2. Publish `puppeteer` to npm.
-    1. On your local machine, pull from [upstream](https://github.com/puppeteer/puppeteer) and make sure the last commit is the one just merged.
-    2. Run `git status` and make sure there are no untracked files.
-        - **WHY**: this is to avoid adding unnecessary files to the npm package.
-    3. Run [`npx pkgfiles`](https://www.npmjs.com/package/pkgfiles) to make sure you don't publish anything unnecessary.
-    4. Run `npm publish`. This publishes the `puppeteer` package.
-3. Publish `puppeteer-core` to npm.
-    1. Run `./utils/prepare_puppeteer_core.js`. The script changes the name inside `package.json` to `puppeteer-core`.
-    2. Run `npm publish`. This publishes the `puppeteer-core` package.
-    3. Run `git reset --hard` to reset the changes to `package.json`.
-4. Source Code: mark post-release.
+    8. As soon as the Git tag is created by completing the previous step, our CI automatically `npm publish`es the new releases for both the `puppeteer` and `puppeteer-core` packages.
+2. Source Code: mark post-release.
     1. Bump `package.json` version to `-post` version, run `npm run doc` to update the “released APIs” section at the top of `docs/api.md` accordingly, and send a PR titled `'chore: bump version to vXXX.YYY.ZZZ-post'` ([example](https://github.com/puppeteer/puppeteer/commit/d02440d1eac98028e29f4e1cf55413062a259156))
         - **NOTE**: no other commits should be landed in-between release commit and bump commit.
 

package.json

@@ -26,6 +26,7 @@
     "lint": "npm run eslint && npm run tsc && npm run doc && npm run commitlint",
     "doc": "node utils/doclint/cli.js",
     "clean-lib": "rm -rf lib",
+    "build": "npm run tsc",
     "tsc": "npm run clean-lib && tsc --version && npm run tsc-cjs && npm run tsc-esm",
     "tsc-cjs": "tsc -b src/tsconfig.cjs.json",
     "tsc-esm": "tsc -b src/tsconfig.esm.json",