How to Try Angular CLI with Bazel

A Happy New Year! I expect this year will be a beginning of Bazel Era!

This post is a reminder note for someone will try Angular CLI with Bazel (referred to as Angular Bazel in this post)at angular/bazel@7.0.0-rc.0.

This is based on Minko Gechev’s introduction post.

Introducing Bazel Schematics for Angular CLI

Environment Preparation

1. Install Bazel

Not mentioned in Minko’s post, Angular Bazel needs global Bazel environment with its version higher than v0.18.0.

$ brew install bazel
$ bazel version
  INFO: Invocation ID: f973b7f6-a2b8-4821-a343-3036ac99183d
  Build label: 0.20.0-homebrew
  Build target: bazel-out/darwin-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
  Build time: Fri Nov 30 20:40:12 2018 (1543610412)
  Build timestamp: 1543610412
  Build timestamp as int: 1543610412

Installing Bazel

2. Install Angular Bazel

To use Bazel schematics with ng new , it has to be installed in the same place to the CLI. In other words, you have to install Angular Bazel with --global flag. If you installed Angular CLI with yarn, execute yarn add --global .

$ npm -g i @angular/bazel@7.2.0-rc.0

3. Create Application

Create new application with ng new .

$ ng new bzl-app --collection=@angular/bazel

As same as Minko’s post, you need to edit some project files like package.json or WORKSPACE.

As far as I tried, SCSS or other AltCSS are not supported by Angular Bazel yet. You have to choose CSS in ng new prompt.

Run application with Bazel

To run Angular application, just execute ng serve .

ng serve command without --prod runs ts_devserver target defined in src/BUILD.bazel .

ts_devserver(
    name = "devserver",
    port = 4200,
    additional_root_paths = [
        "npm/node_modules/zone.js/dist",
        "npm/node_modules/tslib",
    ],
    entry_module = "bzl_app/src/main.dev",
    serving_path = "/bundle.min.js",
    static_files = [
        "@npm//node_modules/zone.js:dist/zone.min.js",
        "@npm//node_modules/tslib:tslib.js",
        "index.html",
    ],
    deps = [":src"],
)

bazelbuild/rules_typescript

Technically, ng serve is the same to bazel run //src:devserver . And then, the below log is shown.

Server listening on http://<Your Machine Name>.local:4200/

This is designed behavior of ts_devserver . But it is not friendly possibly. Here is an issue about it. I think it should show localhost:4200 in the log, too.

ts_devserver should bind to the loopback address by default (localhost) · Issue #339 ·…

With --prod , it uses history_server from Nodejs Rules.

history_server(
    name = "prodserver",
    data = [
        "index.html",
        ":bundle",
        ":zonejs",
    ],
)

Run history-server

Notable thing is Angular Bazel provides different servers for development and production. It is more performant than ts_devserver but not easy to debug.

Build application with Bazel

Angular Bazel already supports ng build --prod . But its build output is completely different to today’s non-Bazel ng build .

After runningng build --prod , dist directory has some sub directories and many output files. In Angular Bazel, dist/bzl-app directory is not _serve-able_ with other simple HTTP server, because it doesn’t contain index.html . It is not regular structure.

dist
├── bin
├── bzl-app
├── genfiles
├── out
└── testlogs

To run application built by ng build --prod , execute dist/bin/src/prodserver executable file. It runs history_server as same as ng serve --prod . It’s a very performant web server implemented in Go.

$ ./dist/bin/src/prodserver --port=4200

So currently, to deploy the application, you have to follow the below steps;

1. Build application
2. Copy dist to remote server
3. Execute prodserver with Bazel environment

I think it is not easy, and Angular Bazel should support typical simple build output to deploy to web hosting ecosystems like GitHub Pages, Netlify, or Firebase Hosting.

Conclusion

• Install Bazel and Angular Bazel
• Create application with --collection=@angular/bazel
• ng serve and ng build --prod are supported
• Built output is very different to today’s CLI

Angular Bazel is still in RC.0. I’ll try next release.