---
lang: en
title: 'API docs: boot'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/boot
permalink: /doc/en/lb4/apidocs.boot.html
---

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[Home](./index.md) &gt; [@loopback/boot](./boot.md)

## boot package

A convention based project Bootstrapper and Booters for LoopBack Applications.

## Remarks

A Booter is a class that can be bound to an Application and is called to perform a task before the Application is started. A Booter may have multiple phases to complete its task. The task for a convention based Booter is to discover and bind Artifacts (Controllers, Repositories, Models, etc.).

An example task of a Booter may be to discover and bind all artifacts of a given type.

A Bootstrapper is needed to manage the Booters and execute them. This is provided in this package. For ease of use, everything needed is packages using a BootMixin. This Mixin will add convenience methods such as `boot` and `booter`<!-- -->, as well as properties needed for Bootstrapper such as `projectRoot`<!-- -->. The Mixin also adds the `BootComponent` to your `Application` which binds the `Bootstrapper` and default `Booters` made available by this package.

## Classes

|  Class | Description |
|  --- | --- |
|  [ApplicationMetadataBooter](./boot.applicationmetadatabooter.md) | Configure the application with metadata from <code>package.json</code> |
|  [BaseArtifactBooter](./boot.baseartifactbooter.md) | This class serves as a base class for Booters which follow a pattern of configure, discover files in a folder(s) using explicit folder / extensions or a glob pattern and lastly identifying exported classes from such files and performing an action on such files such as binding them.<!-- -->Any Booter extending this base class is expected to<!-- -->1. Set the 'options' property to a object of ArtifactOptions type. (Each extending class should provide defaults for the ArtifactOptions and use Object.assign to merge the properties with user provided Options). 2. Provide it's own logic for 'load' after calling 'await super.load()' to actually boot the Artifact classes.<!-- -->Currently supports the following boot phases: configure, discover, load. |
|  [BootComponent](./boot.bootcomponent.md) | BootComponent is used to export the default list of Booter's made available by this module as well as bind the BootStrapper to the app so it can be used to run the Booters. |
|  [Bootstrapper](./boot.bootstrapper.md) | The Bootstrapper class provides the <code>boot</code> function that is responsible for finding and executing the Booters in an application based on given options.<!-- -->NOTE: Bootstrapper should be bound as a SINGLETON so it can be cached as it does not maintain any state of it's own. |
|  [ControllerBooter](./boot.controllerbooter.md) | A class that extends BaseArtifactBooter to boot the 'Controller' artifact type. Discovered controllers are bound using <code>app.controller()</code>.<!-- -->Supported phases: configure, discover, load |
|  [DataSourceBooter](./boot.datasourcebooter.md) | A class that extends BaseArtifactBooter to boot the 'DataSource' artifact type. Discovered DataSources are bound using <code>app.dataSource()</code>.<!-- -->Supported phases: configure, discover, load |
|  [InterceptorProviderBooter](./boot.interceptorproviderbooter.md) | A class that extends BaseArtifactBooter to boot the 'InterceptorProvider' artifact type.<!-- -->Supported phases: configure, discover, load |
|  [LifeCycleObserverBooter](./boot.lifecycleobserverbooter.md) | A class that extends BaseArtifactBooter to boot the 'LifeCycleObserver' artifact type.<!-- -->Supported phases: configure, discover, load |
|  [ModelApiBooter](./boot.modelapibooter.md) |  |
|  [ModelBooter](./boot.modelbooter.md) | A class that extends BaseArtifactBooter to boot the 'Model' artifact type.<!-- -->Supported phases: configure, discover, load |
|  [RepositoryBooter](./boot.repositorybooter.md) | A class that extends BaseArtifactBooter to boot the 'Repository' artifact type. Discovered repositories are bound using <code>app.repository()</code> which must be added to an Application using the <code>RepositoryMixin</code> from <code>@loopback/repository</code>.<!-- -->Supported phases: configure, discover, load |
|  [ServiceBooter](./boot.servicebooter.md) | A class that extends BaseArtifactBooter to boot the 'Service' artifact type. Discovered services are bound using <code>app.service()</code>.<!-- -->Supported phases: configure, discover, load |

## Functions

|  Function | Description |
|  --- | --- |
|  [bindBooter(ctx, booterCls)](./boot.bindbooter.md) | Method which binds a given Booter to a given Context with the Prefix and Tags expected by the Bootstrapper |
|  [booter(artifactNamespace, specs)](./boot.booter.md) | <code>@booter</code> decorator to mark a class as a <code>Booter</code> and specify the artifact namespace for the configuration of the booter |
|  [BootMixin(superClass)](./boot.bootmixin.md) | Mixin for @<!-- -->loopback/boot. This Mixin provides the following: - Implements the Bootable Interface as follows. - Add a <code>projectRoot</code> property to the Class - Adds an optional <code>bootOptions</code> property to the Class that can be used to store the Booter conventions. - Adds the <code>BootComponent</code> to the Class (which binds the Bootstrapper and default Booters) - Provides the <code>boot()</code> convenience method to call Bootstrapper.boot() - Provides the <code>booter()</code> convenience method to bind a Booter(s) to the Application - Override <code>component()</code> to call <code>mountComponentBooters</code> - Adds <code>mountComponentBooters</code> which binds Booters to the application from <code>component.booters[]</code> |
|  [createBooterForComponentApplication(componentApp, filter)](./boot.createbooterforcomponentapplication.md) | Create a booter that boots the component application. Bindings that exist in the component application before <code>boot</code> are skipped. Locked bindings in the main application will not be overridden. |
|  [createComponentApplicationBooterBinding(componentApp, filter)](./boot.createcomponentapplicationbooterbinding.md) | Create a binding to register a booter that boots the component application. Bindings that exist in the component application before <code>boot</code> are skipped. Locked bindings in the main application will not be overridden. |
|  [discoverFiles(pattern, root)](./boot.discoverfiles.md) | Returns all files matching the given glob pattern relative to root |
|  [isClass(target)](./boot.isclass.md) | Given a function, returns true if it is a class, false otherwise. |
|  [loadClassesFromFiles(files, projectRootDir)](./boot.loadclassesfromfiles.md) | Returns an Array of Classes from given files. Works by requiring the file, identifying the exports from the file by getting the keys of the file and then testing each exported member to see if it's a class or not. |

## Interfaces

|  Interface | Description |
|  --- | --- |
|  [Bootable](./boot.bootable.md) | Interface to describe the additions made available to an Application that uses BootMixin. |
|  [Booter](./boot.booter.md) | Defines the requirements to implement a Booter for LoopBack applications: - configure() - discover() - load()<!-- -->A Booter will run through the above methods in order. |
|  [InstanceWithBooters](./boot.instancewithbooters.md) | Interface to describe an object that may have an array of <code>booters</code>. |

## Namespaces

|  Namespace | Description |
|  --- | --- |
|  [BootBindings](./boot.bootbindings.md) | Namespace for boot related binding keys |
|  [BootTags](./boot.boottags.md) | Namespace for boot related tags |

## Variables

|  Variable | Description |
|  --- | --- |
|  [\_bindBooter](./boot._bindbooter.md) |  |
|  [bindingKeysExcludedFromSubApp](./boot.bindingkeysexcludedfromsubapp.md) | Binding keys excluded from a sub application. These bindings booted from the sub application won't be added to the main application. |
|  [BOOTER\_PHASES](./boot.booter_phases.md) | Export of an array of all the Booter phases supported by the interface above, in the order they should be run. |
|  [ControllerDefaults](./boot.controllerdefaults.md) | Default ArtifactOptions for ControllerBooter. |
|  [DataSourceDefaults](./boot.datasourcedefaults.md) | Default ArtifactOptions for DataSourceBooter. |
|  [InterceptorProviderDefaults](./boot.interceptorproviderdefaults.md) | Default ArtifactOptions for InterceptorProviderBooter. |
|  [LifeCycleObserverDefaults](./boot.lifecycleobserverdefaults.md) | Default ArtifactOptions for DataSourceBooter. |
|  [ModelDefaults](./boot.modeldefaults.md) | Default ArtifactOptions for DataSourceBooter. |
|  [RepositoryDefaults](./boot.repositorydefaults.md) | Default ArtifactOptions for RepositoryBooter. |
|  [RestDefaults](./boot.restdefaults.md) | Default ArtifactOptions for ControllerBooter. |
|  [ServiceDefaults](./boot.servicedefaults.md) | Default ArtifactOptions for DataSourceBooter. |

## Type Aliases

|  Type Alias | Description |
|  --- | --- |
|  [ArtifactOptions](./boot.artifactoptions.md) | Type definition for ArtifactOptions. These are the options supported by this Booter. |
|  [BootExecutionOptions](./boot.bootexecutionoptions.md) | Options for boot() execution |
|  [BootOptions](./boot.bootoptions.md) | Options to configure <code>Bootstrapper</code> |


