Deprecate Bower Support

Summary

This RFC proposes to deprecate the following Bower APIs:

• Blueprint::addBowerPackageToProject
• Blueprint::addBowerPackagesToProject
• Project::bowerDependencies (not public, but used in several addons)
• Project::bowerDirectory (not public, but used in several addons)

This RFC also proposes to deprecate building Bower packages, coming from /bower_components by default.

Motivation

While Bower is still maintained, it's recommended to use an alternative package manager instead (npm, Yarn, pnpm, …). This is also the official recommendation of the Bower team. Additionally, Ember CLI stopped emitting a bower.json file since v2.13.0 and the Ember Guides recommend to not use Bower anymore as well in the Compiling Assets section. Lastly, most addons have dropped support for Bower as well.

Putting this all together, deprecating (and later on removing) Bower support seems like the best path forward.

Transition Path

Blueprint::addBowerPackageToProject

Adds a Bower package to the project's bower.json file.

When used, a deprecation message will be triggered suggesting to use Blueprint::addPackageToProject instead:

`addBowerPackageToProject` has been deprecated. If the package is also available
on the npm registry, please use `addPackageToProject` instead. If not, please
suggest your users to install the Bower package manually by running:
`bower install <package-name> --save`.

Deprecation details:

Key	Value
for	'ember-cli'
id	'ember-cli.blueprint.add-bower-package-to-project'
since	{ available: '4.X.X', enabled: '4.X.X' }
until	'5.0.0'

Blueprint::addBowerPackagesToProject

Adds multiple Bower packages to the project's bower.json file.

When used, a deprecation message will be triggered suggesting to use Blueprint::addPackagesToProject instead:

`addBowerPackagesToProject` has been deprecated. If the packages are also available
on the npm registry, please use `addPackagesToProject` instead. If not, please
suggest your users to install the Bower packages manually by running:
`bower install <package-name> <package-name> --save`.

Deprecation details:

Key	Value
for	'ember-cli'
id	'ember-cli.blueprint.add-bower-packages-to-project'
since	{ available: '4.X.X', enabled: '4.X.X' }
until	'5.0.0'

Project::bowerDependencies

Returns the Bower dependencies (including the development dependencies) for the project.

Addons that use this method, mostly do so to check the presence of a specific Bower package in order to suggest users to use the npm equivalent instead.

When used, the following deprecation message will be triggered:

`bowerDependencies` has been deprecated. If you still need access to the
project's Bower dependencies, you will have to manually resolve the project's
`bower.json` file instead.

Deprecation details:

Key	Value
for	'ember-cli'
id	'ember-cli.project.bower-dependencies'
since	{ available: '4.X.X', enabled: '4.X.X' }
until	'5.0.0'

Project::bowerDirectory

Returns the project's Bower directory.

When used, the following deprecation message will be triggered:

`bowerDirectory` has been deprecated. If you still need access to the
project's Bower directory, you will have to manually resolve the project's
`.bowerrc` file and read the `directory` property instead.

Deprecation details:

Key	Value
for	'ember-cli'
id	'ember-cli.project.bower-directory'
since	{ available: '4.X.X', enabled: '4.X.X' }
until	'5.0.0'

Building Bower Packages

If Ember CLI detects that the project contains a Bower directory, it will try to build a Broccoli tree with Bower packages.

When a Bower directory is detected, the following deprecation message will be triggered:

Building Bower packages has been deprecated. You have Bower packages in
`<bower-directory>`.

The deprecation message should be triggered when the packageBower method is called.

Deprecation details:

Key	Value
for	'ember-cli'
id	'ember-cli.building-bower-packages'
since	{ available: '4.X.X', enabled: '4.X.X' }
until	'5.0.0'

Additional Tasks

• Remove all Bower references from the app and addon blueprints

Deprecation Guide

Blueprint::addBowerPackageToProject

addBowerPackageToProject has been deprecated. If the package is also available on the npm registry, please use addPackageToProject instead. If not, please suggest your users to install the Bower package manually by running:

bower install <package-name> --save

Blueprint::addBowerPackagesToProject

addBowerPackagesToProject has been deprecated. If the packages are also available on the npm registry, please use addPackagesToProject instead. If not, please suggest your users to install the Bower packages manually by running:

bower install <package-name> <package-name> --save

Project::bowerDependencies

bowerDependencies has been deprecated. If you still need access to the project's Bower dependencies, you will have to manually resolve the project's bower.json file instead:

'use strict';

const fs = require('fs-extra');
const path = require('path');

module.exports = {
  name: require('./package').name,

  included() {
    this._super.included.apply(this, arguments);

    let bowerPath = path.join(this.project.root, 'bower.json');
    let bowerJson = fs.existsSync(bowerPath) ? require(bowerPath) : {};
    let bowerDependencies = {
      ...bowerJson.dependencies,
      ...bowerJson.devDependencies,
    };

    // Do something with `bowerDependencies`.
  },
};

Project::bowerDirectory

bowerDirectory has been deprecated. If you still need access to the project's Bower directory, you will have to manually resolve the project's .bowerrc file and read the directory property instead:

'use strict';

const fs = require('fs-extra');
const path = require('path');

module.exports = {
  name: require('./package').name,

  included() {
    this._super.included.apply(this, arguments);

    let bowerConfigPath = path.join(this.project.root, '.bowerrc');
    let bowerConfigJson = fs.existsSync(bowerConfigPath) ? fs.readJsonSync(bowerConfigPath) : {};
    let bowerDirectory = bowerConfigJson.directory || 'bower_components';

    // Do something with `bowerDirectory`.
  },
};

Building Bower Packages

Building Bower packages has been deprecated.

Please consider one of the following alternatives:

1. Install the package via the npm registry and use ember-auto-import to import the package into your project
2. If alternative 1 is not an option, you could copy the contents of the Bower package into the /vendor folder and use app.import to import the package into your project

How We Teach This

The following references to Bower in the Ember Guides should be removed:

• Compiling Assets

The following references to Bower in the Ember CLI Guides should be removed:

• Where Should Assets and Dependencies Go?
• Assets and Dependencies
• ember addon
• ember init
• ember new
• Blueprint Hooks
• WebStorm

We should also make sure to remove all references to Bower in the Ember CLI API documentation.

NOTE: It's possible that some references are not included in the lists above.

Drawbacks

• Addons that still rely on a Bower package which does not yet have an npm equivalent would need to suggest their users to manually install said package
• Addons that still require access to the project's Bower dependencies, will have to manually resolve the project's bower.json file instead
• Addons that still require access to the project's Bower directory, will have to manually resolve the project's .bowerrc file and read the directory property instead
• Projects that still import Bower packages will need to use one of the suggested alternatives in the Building Bower Packages deprecation guide

Alternatives

• Keep supporting Bower indefinitely

Unresolved questions

• Should a deprecation warning be displayed when the --skip-bower CLI flag is used?