Angular CLI Packagr Tasks

Tasks & Workflow for ng-packagr.

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Version 9 support angular version 9 and above.

For angular 8 or lower use version 4.

For angular 7 or lower use version 3.

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TL;DR

Hook into the build steps of ng-packger and add custom behaviors or change the built in behaviors.

Examples:

• Copy files after package build
• Bump version (semver)
• Build node libraries instead of angular libraries.

How it works?

For every package, ng-packagr will run several tasks through its' pipeline.
This library exposes an API to hook into the pipeline, each step in ng-packagr has a unique hook in the API.

To alter the behavior each hook is split into 3 phases before and/or after each task and even replacing the built-in task completely.

For each hook/phase combination we can register a handler function (or an array of them) that will be called at that specific phase. The handler has access to a lot of data including ng-packagr API, architect API and more...

There are 6 hooks: initTsConfig, analyseSources, entryPoint, compileNgc, writeBundles, writePackage.
Because there are 3 phases for each hook (before, replace, after) there are 18 points of contact.

The handlers are the most basic form of interaction, we can combine several handlers registered at specific points into a Job.

A Job is just a collection of handlers that together perform an operation, for example creating a node-library instead of angular library. Jobs can also accept input (through angular.json), which are type safe as we run validation on them.

The library comes with some built-in jobs but you can easily create your own.

Install

yarn add ng-cli-packagr-tasks -D

Configuration

Here is a simple CLI configuration for a library (angular.json):

"architect": {
  "build": {
    "builder": "@angular-devkit/build-ng-packagr:build",
    "options": {
      "tsConfig": "tsconfig.lib.json",
      "project": "ng-package.json"
    },
    "configurations": {
      "production": {
        "project": "ng-package.prod.json"
      }
    }
  }
}

This will run the classic ng-packagr build process.

Let's update it a bit:

"architect": {
  "build": {
    "builder": "ng-cli-packagr-tasks:build",
    "options": {
      "tsConfig": "tsconfig.lib.json",
      "project": "ng-package.json",
      "tasks": {
        "config": "ng-packagr.transformers.ts"
      }
    },
    "configurations": {
      "production": {
        "project": "ng-package.prod.json"
      }
    }
  }
}

We've introduces 2 changes:

• The builder has changed from @angular-devkit/build-ng-packagr:build to ng-cli-packagr-tasks:build.
• The property tasks was added, pointing to a configuration module where we can tweak the process.

Note that ng-packagr itself does not change, only the architect builder.

The tasks object has additional properties which we can use to customize the process and provide configuration for tasks. We will cover this shortly, for now let's focus on the configuration module (tasks.config).

Configuration module

The configuration module is a simple JS (or TS) file that exports (default) the transformation instructions, there are 2 ways:

• Direct transformer hook configuration (NgPackagerHooks)
• A function. (ctx: NgPackagerHooksContext<T>, registry: HookRegistry) => void | Promise<void>

Regardless of how you choose to export the instructions (function or object), the end result is always the NgPackagerTransformerHooks. When using functions you register handlers through the HookRegistry, which also allow registering jobs.

The only way to use jobs is through a function, which provide access to the HookRegistry.

Packagr hooks (NgPackagerTransformerHooks)

ng-packagr has several build steps, in a certain order, that together form the process of creating a library in the angular package format spec. NgPackagerHooks is a map of hooks within the packaging process that you can tap in to, each hook correspond to a specific packagr step.

export interface NgPackagerHooks {
  initTsConfig?: TaskPhases<TaskContext<[ParsedConfiguration]>>;
  analyseSources?: TaskPhases<TaskContext>;
  entryPoint?: TaskPhases;
  compileNgc?: TaskPhases;
  writeBundles?: TaskPhases;
  writePackage?: TaskPhases;
}

The order which the tasks run reflect in the order of the properties above.

For example, compileNgc will compile the library (TS -> JS, twice in 2 formats).

ng-packager has more tasks, running before analyseSources but they do not provide any value for customization.

Each hook is split into 3 phases...

Task phases (TransformerHook)

For each hook there are 3 phases which you can register (all optional): before, replace and after

export interface TaskPhases<T = EntryPointTaskContext> {
  before?: TaskOrTasksLike<T>;
  replace?: TaskOrTasksLike<T>;
  after?: TaskOrTasksLike<T>;
}

The order which the phases run are: before -> replace -> after

The timeline is relative to the replace phase, which is where the original ng-packagr task runs. If you set a hook handler in replace the original task from ng-packagr WILL NOT RUN.

Do not set a handler in replace unless you really know what you are doing!

Each phase accepts a single task or an array of tasks, for now let's define a task as a function that handles that hook:

export type HookHandler<T> = (taskContext: T) => (BuildGraph | void | Promise<BuildGraph> | Promise<void>);

The hook is invoked with a taskContext parameter.

The context holds metadata and APIs for the current task and globally for the entire process.

/**
 * A context for hooks running at the initialization phase, when all entry points are discovered and all initial values are loaded.
 */
export interface TaskContext<T = any[]> {
  /**
   * A tuple with injected objects passed to the factory of the transformer.
   */
  factoryInjections: T;

  /**
   * The main build graph
   */
  graph: BuildGraph;

  context<Z extends NgPackagrBuilderTaskSchema = TData>(): NgPackagerHooksContext<Z>;

  taskArgs(key: string): string | undefined;
}

/**
 * A context for hook handlers running at the processing phase, where each entry point is being processed in a sequence, one after the other.
 */
export interface EntryPointTaskContext<T = any[]> extends TaskContext<T> {
  epNode: EntryPointNode;
}

EntryPointTaskContext handlers are called multiple times, once for every package (primary and secondary). TaskContext is called once before starting to process packages

There are 2 types of tasks:

• A simple function (HookHandler)
• A job

The first is just a function that implements (HookHandler), best suited for ad-hoc quick tasks.

Job are more strict and organized, they usually require input and they also provide a schema to validate against that input. (see copy example below). A job can spread over several hooks.

The input for all typed tasks is always through tasks.data where each typed task has a "namespace" which is a property on the data object that points to it's own input object.

The library comes with several built in jobs.

You can review the source code for some of the built-in jobs and build your own.

Examples

Before we dive into examples, it's important that we understand what information is available to us, provided by ng-packagr.

Most of it is stored in EntryPointNode. The EntryPointNode object contains a lot of things. File path locations (sources, destinations), cached files, cache TS compiler programs and more...

If we want to copy or move files, delete, build something etc, we need to know where the resources are located...

There isn't much documentation, but it is typed which should be enough.

• Filtering build of packages (custom task)
• Copy files and Bump version (built-in tasks)
• Node Library (built-in tasks)
• API Metadata generator
• Modify TS compilation settings in secondary entry points

TODO:

• Example on information in EntryPointNode (destination, metadata etc...)
• Example for theme builder (e.g. scss)