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# Example Angular monorepo using Bazel

There are a few ways to use Angular with Bazel. See https://bazelbuild.github.io/rules_nodejs/examples#angular for an overview of all the options.

This example demonstrates the Google-internal toolchain, which is fast but not very compatible with existing applications.

## Guide to the example

This example is a monorepo, meant to show many different features and integrations that we expect are generally useful for enterprise use cases.

- **Angular CLI**: you can use the `ng` command to run build, serve, test, and e2e
- **Angular Libraries**: to maximize build incrementality, each Angular module is compiled as a separate step. This lets us re-use Angular libraries without having to publish them as npm packages. See `src/todos` for a typical `NgModule` compiled as a library for use in the application, using the `ts_library` rule in the `BUILD.bazel` file.
- **TypeScript Libraries**: see `src/lib` for a trivial example of a pure-TS library that's consumed in the application, using the `ts_library` rule in the `BUILD.bazel` file.
- **Sass**: we use Sass for all styling. Angular components import Sass files, and these are built by Bazel as independent processes calling the modern Sass compiler (written in Dart).
- **Material design**: see `src/material` where we collect the material modules we use.
- **Redux-style state management**: see `src/reducers` where we use the [NgRx Store](https://ngrx.io/guide/store).
- **Lazy loading**: in production mode, the application is served in chunks. Run `ng serve --prod`
- **Differential loading**: in production mode, we load a pair of `<script>` tags. Modern browsers will load code in the ES2015 syntax, which is smaller and requires fewer polyfills. Older browsers will load ES5 syntax.
- **Docker**: see below where we package up the production app for deployment on Kubernetes.
- **Server Side Rendering**: with the help of Angular Universal you can render your application on the server

This example is deployed at https://bazel.angular.io/example

## Installation

You only need to install one build tool, and which one you choose typically depends on what kind of development you do most often.

If you're a frontend developer, you should install NodeJS and yarn.
The `package.json` file has an `engines` section which indicates the range of NodeJS and yarn versions that you could use.
You simply run `yarn` commands shown below, and don't need to install Bazel or any other dependencies.

If you're a full-stack developer, you might be using Bazel for your backend already.
In this case, you should install Bazel following instructions at http://bazel.build.
Also install `ibazel`, which is a watch mode for Bazel not included in the standard distribution. See https://github.com/bazelbuild/bazel-watcher#installation.
You should have a `.bazelversion` file which will ensure Bazel prints an error if your Bazel version is not in the supported range.
You simply run `bazel` commands shown below, and don't need to install NodeJS, yarn, or any other dependencies.

## Development

First we'll run the development server:

```bash
$ ng serve
# or
$ ibazel run //src:devserver
```

This runs in "watch mode", which means it will watch any files that are inputs to the devserver, and when they change it will ask Bazel to re-build them.
When the re-build is finished, it will trigger a 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.

## Testing

We can also run all the unit tests:

```bash
$ ng test
# or
$ bazel test //src/...
```

Or run the end-to-end tests:

```bash
$ ng e2e
# or
$ bazel test //e2e/...
```

In this example, there is a unit test for the `hello-world` component which uses
the `karma_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.

```bash
$ ng serve --prod
# or
$ bazel run //src:prodserver
```

You can also use server side rendering.

```bash
$ yarn server-ssr
# or
$ bazel run //src:universal_server
```

### Code splitting

The production bundle is code split and routes such as `/` and `/todos`
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. The dynamic
`import()` statements will resolve to modules that are served in the initial
JS payload.

### Prerendering

The production build has a number of routes prerendered to `index.html` files. 
This is similar to the process used in Angular Universal. The `ng_prerender` macro in the `tools` directory is
used to run the application during the build, and output the `index.html` files for the requested routes.

A smoke test is also included with `ng_prerender_test` macro, which checks key elements in the prerendered output. 

## Npm dependencies

Having a local `node_modules` folder setup by `yarn` or `npm` is not
necessary when building this example with Bazel. This example makes use
of Bazel managed npm dependencies (https://github.com/bazelbuild/rules_nodejs#using-bazel-managed-dependencies)
which means Bazel will setup the npm dependencies in your `package.json` for you
outside of your local workspace for use in the build.

However, you may still want to run `yarn` or `npm` to manually
setup a local `node_modules` folder for editor and tooling support.

## Deployment

### Firebase

We use the standard firebase deploy command.

Run `yarn deploy` to release changes to bazel.angular.io.

### Kubernetes Engine

We use Bazel's docker support to package up our production server for deployment.
Each time the app changes, we'll get a slim new docker layer with just the modified files, keeping the round-trip for deployment incremental and fast.
This example is configured to run on Google Kubernetes Engine, so we can have an elastic pool of backend machines behind a load balancer.
This setup is more expensive to operate than something like Firebase Functions where the backend code is spun up on-demand, but is also more adaptable to scenarios like backend servers that need to run other binaries on the machine.

The application is currently live at http://35.197.115.230/

To run it under docker:

```
$ bazel run src:nodejs_image -- --norun
$ docker run --rm -p 8080:8080 bazel/src:nodejs_image
```

Deploy to production:

1. Install gcloud and kubectl
1. Authenticate to the Google Container Registry
   `gcloud auth configure-docker`
1. Authenticate to Kubernetes Engine
   `gcloud container clusters get-credentials angular-bazel-example --zone=us-west1-a`
1. For the first deployment: `bazel run :deploy.create`
1. To update: `bazel run :deploy.replace`

Tips:

```
# Run the binary without docker
$ bazel run src:nodejs_image.binary
 # What's in the image?
$ bazel build src:nodejs_image && file-roller dist/bin/src/nodejs_image-layer.tar
 # Tear down all running docker containers
$ docker rm -f $(docker ps -aq)
 # Hop into the running image on kubernetes
$ kubectl exec angular-bazel-example-prod-3285254973-ncv3g  -it -- /bin/bash
```