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Nx CLI

The Nx CLI is a command-line interface tool that helps you setup, develop, build, and maintain applications. It provides commands for:

  • Generating new applications, and libraries with recommended defaults.
  • Running a development webserver that rebuilds your app on changes.
  • Generating a dependency graph for your application.
  • Building, and running unit and E2E test for apps, and libraries affected by your changes.
  • Formatting your source code to modern standards.
  • ...

Nx CLI and Angular CLI

The Nx CLI supports different types of generators and executors. When running Angular Devkit schematics (e.g., generating an Angular component), the Nx CLI will use Angular Devkit under the hood. So the result will be exactly the same as if you used the Angular CLI. When running Angular Devkit builders, the Nx CLI once again will use the same Angular Devkit under the hood.

In other words, anything the Angular CLI can run, the Nx CLI can run as well because it uses the same Angular Devkit written by the Angular team under the hood. Except that using the Nx CLI is often a lot faster because of its powerful computation caching and code change analysis.

The Nx CLI also supports a lot more commands than the Angular CLI. It can run a target against many projects in parallel, run a target against a project and its dependencies, visualize the dependency graph etc..

Nx will create the decorate-angular-cli.js file in a new Nx workspace. This file essentially "wraps" the Angular CLI to give you computation caching and other powerful feature, so running nx build myapp and ng build myapp will produce the same result.

Installing the CLI

Install the Nx CLI globally on your system using your preferred package manager:

Using npm:

npm install -g nx

Using yarn:

yarn global add nx

After that, you will have an nx executable you can use to run commands in your workspace.

If you don't have the Nx CLI installed globally, you can invoke nx using yarn nx and npm run nx.

Help and List

nx help will print a short description of every command. You can also pass --help to a command to see the available options (e.g., nx affected --help).

nx list will print the list of installed plugins and the list of plugins you can install. You can also pass a plugin name to it (e.g., nx list @nrwl/angular) to learn more about what the capabilities of that plugin.

Generating Code

The Nx CLI has an advanced code generator. With it, you can generate new applications, libraries, components, state management utilities. You can change existing applications. And, because the Nx CLI comes with an implementation of a virtual file system, you can preview the changes without affecting anything on disk.

The code generation recipes are called generators. Generators provide the underlying APIs for scaffolding, and utilities to automate changes to your filesystem. The example below is the command to generate a new application.

nx generate @nrwl/angular:application myapp

The @nrwl/angular package contains a collection of generators, with application being the one used in this example. The Nx CLI applies the generator to your workspace, verifying that the provided options are valid, and the destination files don't already exist. Once the validations are passed, the new files are generated, or existing files are updated. You can also customize the output of the generated application, by passing options to the generator.

nx generate @nrwl/angular:application myapp --style=scss

You can preview the changes a generator makes by using the --dry-run option. It will output the potential files created, and/or updated during the execution of the generator.

Generate command:

nx generate runs generators to create or modify code given some inputs from the developer.

  • nx generate
    Syntax: nx generate [plugin]:[generator-name] [options]
    Example: nx generate @nrwl/angular:component mycmp --project=myapp

Running Tasks

The Nx CLI uses builders to perform tasks, such as building and bundling your application, running unit tests, or running E2E tests against a specific target, whether that be an application or workspace.

A builder is a function that uses the Architect API to perform a complex process such as "build", "test", or "lint".

You can configure the builders in angular.json.

{
  "projects": {
    "todos": {
      "root": "apps/todos/",
      "sourceRoot": "apps/todos/src",
      "projectType": "application",
      "architect": {
        "serve": {
          "builder": "@nrwl/web:dev-server",
          "options": {
            "buildTarget": "todos:build",
            "proxyConfig": "apps/todos/proxy.conf.json"
          },
          "configurations": {
            "production": {
              "buildTarget": "todos:build:production"
            }
          }
        },
        "test": {
          "builder": "@nrwl/jest:jest",
          "options": {
            "jestConfig": "apps/todos/jest.config.js",
            "tsConfig": "apps/todos/tsconfig.spec.json",
            "setupFile": "apps/todos/src/test-setup.ts"
          }
        }
      }
    }
  }
}

In the example above, the todos application has two targets: serve and test. The serve target uses the @nrwl/web:dev-server builder, and the test target uses @nrwl/jest:jest. Every target uses a builder which actually runs this target. So targets are analogous to typed npm scripts, and builders are analogous to typed shell scripts.

You can run the target as follows:

nx run todos:serve
nx run todos:test

A target can have multiple configuration. In the example above the serve target has two configurations: default and production.

nx run todos:serve # default configuration
nx run todos:serve:production # production configuration

Because running target is such a common operation, you can also use the following syntax to do it:

nx serve todos
nx serve todos --configuration=production
nx serve todos --prod

You can name your targets any way you want, define as many of them as you want, and use any builders you want to implement them.

These are some common targets:

  • nx build
    Syntax: nx build [project]
    Long form: nx run [project]:build
    Example: nx build my-app
  • nx lint
    Syntax: nx lint [project]
    Long form: nx run [project]:lint
    Example: nx lint my-app
  • nx serve
    Syntax: nx serve [project]
    Long form: nx run [project]:serve
    Example: nx serve my-app
  • nx e2e
    Syntax: nx e2e [project]
    Long form: nx run [project]:e2e
    Example: nx e2e my-app
  • nx test
    Syntax: nx test [project]
    Long form: nx run [project]:test
    Example: nx test my-app

Running Tasks for Multiple Projects

Nx allows you to run tasks across multiple projects.

Run-Many

Run the same target for all projects.

nx run-many --target=build --all

Run the same target for all projects in parallel.

nx run-many --target=build --all --parallel --maxParallel=8

Run the same target for selected projects.

nx run-many --target=build --projects=app1,app2

Run the same target for selected projects and their deps.

nx run-many --target=build --projects=app1,app2 --with-deps

Run the same target for the projects that failed last time.

nx run-many --target=build --all --only-failed

Any flags you pass to run-many that aren't Nx specific will be passed down to the builder.

nx run-many --target=build --all --prod

Affected

Run the same target for all the projects by the current code change (e.g., current Git branch).

nx affected --target=build

Same but in parallel.

nx affected --target=build --parallel --maxParallel=8

By default, the current code change is defined as a diff between master and HEAD. You can change it as follows:

nx affected --target=build --parallel --maxParallel=8 --base=origin/development --head=$CI_BRANCH_NAME

Running affected commands is very common, so Nx comes with a few shortcuts.

nx affected:build
nx affected:test
nx affected:lint
nx affected:e2e

Any flags you pass to run-many that aren't Nx specific will be passed down to the builder.

nx affected --target=build --prod

Loading Environment Variables

By default, Nx will load any environment variables you place in the following files:

  1. workspaceRoot/apps/my-app/.local.env
  2. workspaceRoot/apps/my-app/.env
  3. workspaceRoot/.local.env
  4. workspaceRoot/.env

Order is important. Nx will move through the above list, ignoring files it can't find, and loading environment variables into the current process for the ones it can find. If it finds a variable that has already been loaded into the process, it will ignore it. It does this for two reasons:

  1. Developers can't accidentally overwrite important system level variables (like NODE_ENV)
  2. Allows developers to create .local.env files for their local environment and override any project defaults set in .env

For example:

  1. workspaceRoot/apps/my-app/.local.env contains AUTH_URL=http://localhost/auth
  2. workspaceRoot/apps/my-app/.env contains AUTH_URL=https://prod-url.com/auth
  3. Nx will first load the variables from apps/my-app/.local.env into the process. When it tries to load the variables from apps/my-app/.env, it will notice that AUTH_URL already exists, so it will ignore it.

We recommend nesting your app specific env files in apps/your-app, and creating workspace/root level env files for workspace-specific settings (like the Nx Cloud token).

Pointing to custom env files

If you want to load variables from env files other than the ones listed above:

  1. Use the env-cmd package: env-cmd -f .qa.env nx serve
  2. Use the envFile option of the run-commands builder and execute your command inside of the builder

ng add Functionality

To run the equivalent of the Angular CLI's ng add command for a package named my-package, you need to run two commands:

# npm
npm i my-package
nx g my-package:ng-add
# yarn
yarn add my-package
nx g my-package:ng-add

Note: The plugins maintained by Nrwl have init as an alias for ng-add, so you can run nx g @nrwl/angular:init or nx g @nrwl/angular:ng-add.

Other Commands

nx print-affected prints information about affected projects in the workspace.

nx dep-graph launches a visual graph of the dependencies between your projects.

nx affected:dep-graph launches the dependency graph with all affected projects highlighted.

nx list lists all installed and available plugins.

nx report prints basic information about the plugins used

nx format:write formats your code

nx format:check checks that your code is formatted