OAuth

npm version Changelog

$ npm install @feathersjs/authentication-oauth --save

@feathersjs/authentication-oauth allows to authenticate with over 180 oAuth providers (Google, Facebook, GitHub etc.) using grant, an oAuth middleware module for NodeJS.

Configuration

The following settings are available:

  • redirect: The URL of the frontend to redirect to with the access token (or error message). The authentication client handles those redirects automatically. If not set, the authentication result will be sent as JSON instead.
  • defaults: Default grant configuration used for all strategies. The following default options are set automatically:
    • path (default: /oauth) - The oAuth base path
  • <strategy-name> (e.g. twitter): The grant configuration used for a specific strategy.
  • For both defaults and specific strategies, the following options are set automatically:
    • host: Set to host from the configuration
    • protocol: http for development, https for production (when NODE_ENV=production)
    • transport: Set to session (see grant response data)
    • callback: Set to oauth/<name>/authenticate. This should not be changed.

Pro tip: Removing the redirect setting is a good way to troubleshoot oAuth authentication errors.

Standard oAuth authentication can be configured with those options in config/default.json like this:

{
  "authentication": {
    "oauth": {
      "redirect": "/frontend",
      "google": {
        "key": "...",
        "secret": "...",
        "custom_params": { "access_type": "offline" }
      },
      "twitter": {
        "key": "...",
        "secret": "..."
      }
    }
  }
}

Note: All oAuth strategies will by default always look for configuration under authentication.oauth.<name>. If authentication.oauth is not set in the configuration, oAuth authentication will be disabled.

Usage

Flow

There are two ways to initiate oAuth authentication:

  1. Through the browser (most common)

    • User clicks on link to oAuth URL (oauth/<provider>)
    • Gets redirected to provider and authorizes the application
    • Callback to the OauthStrategy which
      • Gets the users profile
      • Finds or creates the user (entity) for that profile
    • The AuthenticationService creates an access token for that entity
    • Redirect to the redirect URL including the generated access token
    • The frontend (e.g. authentication client) uses the returned access token to authenticate
  2. With an existing access token, e.g. obtained through the Facebook mobile SDK

    • Authenticate normally with { strategy: '<name>', access_token: 'oauth access token' }.
    • Calls the OauthStrategy which
      • Gets the users profile
      • Finds or creates the entity for that profile
    • Returns the authentication result

Note: If you are attempting to authenticate using an obtained access token, ensure that you have added the strategy (e.g. 'facebook') to your authStrategies.

oAuth URLs

There are several URLs and redirects that are important for oAuth authentication:

  • http(s)://<host>/oauth/<provider>: The main URL to initiate the oAuth flow. Link to this from the browser.
  • http(s)://<host>/oauth/<provider>/callback: The callback path that should be set in the oAuth application settings
  • http(s)://<host>/oauth/<provider>/authenticate: The internal redirect

In the browser any oAuth flow can be initiated with the following link:

<a href="/oauth/github">Login with GitHub</a>

Account linking

To link an existing user the current access token can be added the oAuth flow query using the feathers_token query parameter:

<a href="/oauth/github?feathers_token=<your access token>">
  Login with GitHub
</a>

This will use the user (entity) of that access token to link the oAuth account to.

Redirects

The redirect configuration option is used to redirect back to the frontend application after oAuth authentication was successful and an access token for the user has been created by the authentication service or if authentication failed. It works cross domain and by default includes the access token or error message in the window location hash. The following configuration

{
  "authentication": {
    "oauth": {
      "redirect": "https://app.mydomain.com/"
    }
  }
}

Will redirect to https://app.mydomain.com/#access_token=<user jwt> or https://app.mydomain.com/#error=<some error message>. The authentication client handles those redirect automatically. It can be customized with the getRedirect() method of OAuthStrategy.

If redirect option is not set, the authentication result data will be sent as JSON instead.

Setup (Express)

expressOauth (for setup see the AuthenticationService) sets up oAuth authentication on a Feathers Express application and can take the following options:

  • authService: The name of the authentication service
  • linkStrategy (default: 'jwt'): The name of the strategy to use for account linking
  • expressSession (default: require('express-session')()): The Express session middleware to use. Uses in-memory sessions by default but may need to be customized to a persistent storage when using multiple instances of the application.
const { expressOauth } = require('@feathersjs/authentication-oauth');

app.configure(expressOauth({
  service: '/v2/authentication'
}));

OAuthStrategy

entityId

oauthStrategy.entityId -> string returns the name of the id property of the entity.

getEntityQuery(profile, params)

oauthStrategy.getEntityQuery(profile, params) -> Promise returns the entity lookup query to find the entity for a profile. By default returns

{
  [`${this.name}Id`]: profile.sub || profile.id
}

getEntityData(profile, entity, params)

oauthStrategy.getEntityData(profile, existing, params) -> Promise returns the data to either create a new or update an existing entity. entity is either the existing entity or null when creating a new entity.

getProfile(data, params)

oauthStrategy.getProfile(data, params) -> Promise returns the user profile information from the oAuth provider that was used for the login. data is the oAuth callback information which normally contains e.g. the oAuth access token.

getRedirect (data)

oauthStrategy.getRedirect(data) -> Promise returns the URL to redirect to after a successful oAuth login and entity lookup or creation. By default it redirects to authentication.oauth.redirect from the configuration with #access_token=<access token for entity> added to the end of the URL. The access_token hash is e.g. used by the authentication client to log the user in after a successful oAuth login. The default redirects do work cross domain.

getCurrentEntity(params)

oauthStrategy.getCurrentEntity(params) -> Promise returns the currently linked entity for the given params. It will either use the entity authenticated by params.authentication or return null.

findEntity(profile, params)

oauthStrategy.findEntity(profile, params) -> Promise finds an entity for a given oAuth profile. Uses { [${this.name}Id]: profile.id } by default.

createEntity(profile, params)

oauthStrategy.createEntity(profile, params) -> Promise creates a new entity for the given oAuth profile. Uses { [${this.name}Id]: profile.id } by default.

updateEntity(entity, profile, params)

oauthStrategy.updateEntity(entity, profile, params) -> Promise updates an existing entity with the given profile. Uses { [${this.name}Id]: profile.id } by default.

authenticate(authentication, params)

oauthStrategy.authenticate(authentication, params) is the main endpoint implemented by any authentication strategy. It is usually called for authentication requests for this strategy by the AuthenticationService.

Customization

Normally, any oAuth provider set up in the configuration will be initialized with the default OAuthStrategy. The flow for a specific provider can be customized by extending OAuthStrategy class and registering it under that name on the AuthenticationService: