Example of building an Angular app with Bazel

This is experimental! There may be breaking changes.

This is part of the ABC project. The overall goal is to make it possible to develop Angular applications the same way we do at Google. See http://g.co/ng/abc for an overview.

You can read the documentation in the wiki of this repository to understand how this works.

Follow angular/angular#19058 for updates.

Installation

Add ibazel to your $PATH:

yarn global add @bazel/ibazel

or

npm install -g @bazel/ibazel

Setup

Before building the app, we install packages, just as with any npm-based development workflow.

$ yarn install

or

$ npm install

For the time being, you need to run your locally installed yarn or npm to install dependencies as shown above. This is because we pull down the @bazel/typescript bazel dependency from npm and that dependency needs to be in place before we can build the project. We're working to resolve this bootstrapping issue. Soon you will be able to skip this step and just do your first Bazel build without needing any install step first.

Development

Next we'll run the development server:

$ yarn serve

This script runs ibazel, which is a "watch mode" for Bazel. That means it will watch any files that are inputs to the devserver, and when they change it will ask Bazel to re-build them. The server stays running, and when the re-build is finished, it will trigger the LiveReload in the browser.

This command prints a URL on the terminal. Open that page to see the demo app running. Now you can edit one of the source files (src/lib/file.ts is an easy one to understand and see the effect). As soon as you save a change, the app should refresh in the browser with the new content. Our intent is that this time is less than two seconds, even for a large application.

Control-C twice to kill the devserver and also stop ibazel.

Testing

We can also run all the unit tests:

$ yarn test

Or run the end-to-end tests:

$ yarn e2e

In this example, there is a unit test for the hello-world component which uses the ts_web_test_suite rule. There are also protractor e2e tests for both the prodserver and devserver which use the protractor_web_test_suite rule.

Note that Bazel will only re-run the tests whose inputs changed since the last run.

Production

We can run the application in production mode, where the code has been bundled and optimized. This can be slower than the development mode, because any change requires re-optimizing the app. This example uses Rollup and Uglify, but other bundlers can be integrated with Bazel.

$ yarn serve-prod

Code splitting

The production bundle is code split and the / and /todos routes are lazy loaded. Code splitting is handled by the rollup_bundle rule which now supports the new code splitting feature in rollup.

Note: code splitting is not supported in development mode yet so the //src:devserver target does not serve a code split bundle. For this reason, development and production use different main entry points (main.dev.ts and main.ts) and different root modules (app.module.dev.ts and app.module.ts). The difference in the entry points and modules is how routes are loaded, with production lazy loading routes and development using a custom NgModuleFactoryLoader loader to disable lazy loading. enableProdMode() is also called in the production entry point.