OIDC Provider

The OIDC Provider Plugin enables you to build and manage your own OpenID Connect (OIDC) provider, granting full control over user authentication without relying on third-party services like Okta or Azure AD. It also allows other services to authenticate users through your OIDC provider.

Key Features:

• Client Registration: Register clients to authenticate with your OIDC provider.
• Dynamic Client Registration: Allow clients to register dynamically.
• Authorization Code Flow: Support the Authorization Code Flow.
• JWKS Endpoint: Publish a JWKS endpoint to allow clients to verify tokens. (Not fully implemented)
• Refresh Tokens: Issue refresh tokens and handle access token renewal using the refresh_token grant.
• OAuth Consent: Implement OAuth consent screens for user authorization, with an option to bypass consent for trusted applications.
• UserInfo Endpoint: Provide a UserInfo endpoint for clients to retrieve user details.

Installation

import { betterAuth } from "better-auth";
import { oidcProvider } from "better-auth/plugins";
 
const auth = betterAuth({
    plugins: [oidcProvider({
        loginPage: "/sign-in", // path to the login page
        // ...other options
    })]
})

npx @better-auth/cli migrate

import { createAuthClient } from "better-auth/client";
import { oidcClient } from "better-auth/client/plugins"
const authClient = createAuthClient({
    plugins: [oidcClient({
        // Your OIDC configuration
    })]
})

Usage

Once installed, you can utilize the OIDC Provider to manage authentication flows within your application.

Register a New Client

To register a new OIDC client, use the oauth2.register method.

const application = await client.oauth2.register({
    name: "My Client",
    redirect_uris: ["https://client.example.com/callback"],
});

Once the application is created, you will receive a client_id and client_secret that you can display to the user.

This Endpoint support RFC7591 compliant client registration.

UserInfo Endpoint

The OIDC Provider includes a UserInfo endpoint that allows clients to retrieve information about the authenticated user. This endpoint is available at /oauth2/userinfo and requires a valid access token.

// Example of how a client would use the UserInfo endpoint
const response = await fetch('https://your-domain.com/api/auth/oauth2/userinfo', {
  headers: {
    'Authorization': 'Bearer ACCESS_TOKEN'
  }
});
 
const userInfo = await response.json();
// userInfo contains user details based on the scopes granted

The UserInfo endpoint returns different claims based on the scopes that were granted during authorization:

• With openid scope: Returns the user's ID (sub claim)
• With profile scope: Returns name, picture, given_name, family_name
• With email scope: Returns email and email_verified

The getAdditionalUserInfoClaim function receives the user object and the requested scopes array, allowing you to conditionally include claims based on the scopes granted during authorization. These additional claims will be included in both the UserInfo endpoint response and the ID token.

Consent Screen

When a user is redirected to the OIDC provider for authentication, they may be prompted to authorize the application to access their data. This is known as the consent screen. By default, Better Auth will display a sample consent screen. You can customize the consent screen by providing a consentPage option during initialization.

import { betterAuth } from "better-auth";
 
export const auth = betterAuth({
    plugins: [oidcProvider({
        consentPage: "/path/to/consent/page"
    })]
})

The plugin will redirect the user to the specified path with a client_id and scope query parameter. You can use this information to display a custom consent screen. Once the user consents, you can call oauth2.consent to complete the authorization.

const res = await client.oauth2.consent({
	accept: true, // or false to deny
});

The client_id and other necessary information are stored in the browser cookie, so you don't need to pass them in the request. If they don't exist in the cookie, the consent method will return an error.

Handling Login

When a user is redirected to the OIDC provider for authentication, if they are not already logged in, they will be redirected to the login page. You can customize the login page by providing a loginPage option during initialization.

import { betterAuth } from "better-auth";
 
export const auth = betterAuth({
    plugins: [oidcProvider({
        loginPage: "/sign-in"
    })]
})

You don't need to handle anything from your side; when a new session is created, the plugin will handle continuing the authorization flow.

Configuration

OIDC Metadata

Customize the OIDC metadata by providing a configuration object during initialization.

import { betterAuth } from "better-auth";
import { oidcProvider } from "better-auth/plugins";
 
export const auth = betterAuth({
    plugins: [oidcProvider({
        metadata: {
            issuer: "https://your-domain.com",
            authorization_endpoint: "/custom/oauth2/authorize",
            token_endpoint: "/custom/oauth2/token",
            // ...other custom metadata
        }
    })]
})

JWKS Endpoint (Not Fully Implemented)

For JWKS support, you need to use the jwt plugin. It exposes the /jwks endpoint to provide the public keys.

Dynamic Client Registration

If you want to allow clients to register dynamically, you can enable this feature by setting the allowDynamicClientRegistration option to true.

const auth = betterAuth({
    plugins: [oidcProvider({
        allowDynamicClientRegistration: true,
    })]
})

This will allow clients to register using the /register endpoint to be publicly available.

Schema

The OIDC Provider plugin adds the following tables to the database:

OAuth Application

Table Name: oauthApplication

OAuth Access Token

Table Name: oauthAccessToken

OAuth Consent

Table Name: oauthConsent

Options

allowDynamicClientRegistration: boolean - Enable or disable dynamic client registration.

metadata: OIDCMetadata - Customize the OIDC provider metadata.

loginPage: string - Path to the custom login page.

consentPage: string - Path to the custom consent page.

getAdditionalUserInfoClaim: (user: User, scopes: string[]) => Record<string, any> - Function to get additional user info claims.