Custom auth adapters

Rebase ships its own authentication — configure it here. This page is the other case: an identity provider you already run, or already pay for.

Custom Auth Adapters

Rebase allows complete replacement of the built-in authentication system via a pluggable authentication architecture. This decouples authentication verification from the database and REST/WebSocket layers, enabling seamless integration with external providers such as Clerk, Auth0, Firebase Auth, or custom JWT identity services.

The AuthAdapter Contract

You can implement the AuthAdapter interface directly for complete control. The interface definition is as follows:

import { Hono } from "hono";
import type { HonoEnv } from "@rebasepro/server";
import { AuthenticatedUser, AuthAdapterCapabilities, UserManagementAdapter, UserCreationPrepareResult, UserCreationFinalizeResult } from "@rebasepro/types";

export interface AuthAdapter {
  /** Unique identifier for this auth adapter (e.g., "clerk", "custom") */
  readonly id: string;

  /**
   * Verifies an incoming HTTP request and returns the authenticated user payload.
   * Called by Hono authentication middleware on every REST endpoint.
   */
  verifyRequest(request: Request): Promise<AuthenticatedUser | null>;

  /**
   * Verifies a raw token string (e.g. for WebSocket connection handshake phase 1).
   * If omitted, a synthetic request is automatically constructed.
   */
  verifyToken?(token: string): Promise<AuthenticatedUser | null>;

  /** Optional user management operations (CRUD) for the panel */
  userManagement?: UserManagementAdapter;

  /** Optional: Mount adapter-specific custom public routes (e.g. callback paths) */
  createAuthRoutes?(): Hono<any, any, any> | undefined;

  /** Optional: Mount adapter-specific admin-only routes */
  createAdminRoutes?(): Hono<any, any, any> | undefined;

  /** Advertise supported capabilities (to customize what the panel shows) */
  getCapabilities(): AuthAdapterCapabilities | Promise<AuthAdapterCapabilities>;

  /** Lifecycle hooks called during backend start and graceful shutdown */
  initialize?(): Promise<void>;
  destroy?(): Promise<void>;

  /** Custom user lifecycle hooks (e.g., hash passwords before collection writes) */
  prepareUserCreation?(
    values: Record<string, unknown>,
    collectionAuth?: unknown
  ): Promise<UserCreationPrepareResult>;

  finalizeUserCreation?(
    entity: { id: string; values: Record<string, unknown> },
    clearPassword?: string
  ): Promise<UserCreationFinalizeResult>;

  /** Static service key to bypass checks for server-to-server calls */
  serviceKey?: string;
}

The Authenticated User Payload

Regardless of the external authentication provider chosen, your adapter must resolve successful token verifications to a uniform AuthenticatedUser object. The Rebase RLS Scope Injector maps these values directly to PostgreSQL session variables inside transactions:

export interface AuthenticatedUser {
  uid: string;                    // Maps to pg local 'app.user_id' -> rebase.uid()
  email: string;                  // User email address
  displayName?: string | null;    // Optional display name
  photoUrl?: string | null;        // Optional avatar URL
  roles: string[];                // Maps to pg local 'app.user_roles' -> rebase.roles()
  isAdmin: boolean;               // Grants global superuser privileges if true
  rawToken?: string;              // The original token string (for downstream forwarding)
  claims?: Record<string, any>;   // Custom claims/metadata (available in rebase.jwt())
}

---

Quick Integration via createCustomAuthAdapter

For standard scenarios (such as validating JWTs from a third-party service), you can use the createCustomAuthAdapter utility. This utility handles capabilities defaults and implements WebSocket token validation out-of-the-box by wrapping your verifyRequest implementation.

Example: Integrating with Clerk

To connect a Rebase backend with Clerk, you can verify Clerk JWT tokens using Clerk’s JSON Web Key Set (JWKS):

import { initializeRebaseBackend } from "@rebasepro/server";
import { createCustomAuthAdapter } from "@rebasepro/server";
import { createRemoteJWKSet, jwtVerify } from "jose";

// Clerk JWKS URL
const CLERK_JWKS_URL = "https://clerk.your-domain.com/.well-known/jwks.json";
const JWKS = createRemoteJWKSet(new URL(CLERK_JWKS_URL));

const clerkAuthAdapter = createCustomAuthAdapter({
    serviceKey: process.env.REBASE_SERVICE_KEY,
    verifyRequest: async (request) => {
        const authHeader = request.headers.get("Authorization");
        const token = authHeader?.replace("Bearer ", "");
        if (!token) return null;

        try {
            // Verify Clerk JWT token against JWKS
            const { payload } = await jwtVerify(token, JWKS);

            const metadata = payload.metadata as Record<string, unknown> | undefined;
            const roles = Array.isArray(metadata?.roles) ? metadata.roles as string[] : [];

            return {
                uid: payload.sub!,
                email: (payload as Record<string, unknown>).email as string || "",
                displayName: (payload as Record<string, unknown>).name as string || null,
                roles: roles,
                isAdmin: roles.includes("admin"),
                claims: payload as Record<string, unknown>
            };
        } catch (error) {
            console.error("Clerk token verification failed:", error);
            return null; // Fail-closed
        }
    },
    capabilities: {
        hasBuiltInAuthRoutes: false, // Login is managed by Clerk UI
        emailPasswordLogin: false,
        registrationEnabled: false,
        passwordReset: false,
        profileUpdate: false,
        sessionManagement: false
    }
});

const backend = await initializeRebaseBackend({
    auth: clerkAuthAdapter,
    // ...
});

Example: Integrating with Firebase Auth

To verify Firebase Auth tokens using Firebase’s public certificates:

import { initializeRebaseBackend } from "@rebasepro/server";
import { createCustomAuthAdapter } from "@rebasepro/server";
import { createRemoteJWKSet, jwtVerify } from "jose";

const FIREBASE_JWKS_URL = "https://www.googleapis.com/robot/v1/metadata/jwk/securetoken@system.gserviceaccount.com";
const JWKS = createRemoteJWKSet(new URL(FIREBASE_JWKS_URL));
const FIREBASE_PROJECT_ID = "my-firebase-project-id";

const firebaseAuthAdapter = createCustomAuthAdapter({
    serviceKey: process.env.REBASE_SERVICE_KEY,
    verifyRequest: async (request) => {
        const authHeader = request.headers.get("Authorization");
        const token = authHeader?.replace("Bearer ", "");
        if (!token) return null;

        try {
            const { payload } = await jwtVerify(token, JWKS, {
                issuer: `https://securetoken.google.com/${FIREBASE_PROJECT_ID}`,
                audience: FIREBASE_PROJECT_ID
            });

            const roles = Array.isArray((payload as Record<string, unknown>).roles) ? (payload as Record<string, unknown>).roles as string[] : [];

            return {
                uid: payload.sub!,
                email: (payload as Record<string, unknown>).email as string || "",
                displayName: (payload as Record<string, unknown>).name as string || null,
                photoUrl: (payload as Record<string, unknown>).picture as string || null,
                roles: roles,
                isAdmin: roles.includes("admin"),
                claims: payload as Record<string, unknown>
            };
        } catch (error) {
            console.error("Firebase token verification failed:", error);
            return null;
        }
    }
});

const backend = await initializeRebaseBackend({
    auth: firebaseAuthAdapter,
    // ...
});

---

Mounting Auth Routes and Panel Actions

If your custom auth provider requires mounting redirect endpoints (like OAuth callback routes or SAML login loops), implement the createAuthRoutes method on your adapter:

const myOauthAdapter: AuthAdapter = {
    id: "custom-oauth",
    verifyRequest: async (req) => ({
        // validate the token, then return the caller
        uid: "…",
        email: "user@example.com",
        roles: [],
        isAdmin: false
    }),
    getCapabilities: () => ({
        hasBuiltInAuthRoutes: true,
        emailPasswordLogin: false,
        registrationEnabled: false,
        passwordReset: false,
        adminPasswordReset: false,
        sessionManagement: false,
        profileUpdate: false,
        emailVerification: false,
        magicLink: false,
        anonymousLogin: false,
        enabledProviders: []
    }),
    createAuthRoutes: () => {
        const app = new Hono<HonoEnv>();

        // Mounted automatically under /api/auth/callback
        app.get("/callback", async (c) => {
            const code = c.req.query("code");
            // Exchange code for provider tokens and set cookies/redirect
            return c.redirect("/dashboard");
        });

        return app;
    }
};

If you wish to allow user CRUD operations directly inside the panel, implement the userManagement helper within the adapter options, which provides hooks for listUsers, createUser, updateUser, and deleteUser.

Next Steps

• Authentication — the built-in provider’s configuration
• Endpoints and tokens — the routes an adapter has to satisfy
• Security Rules (RLS) — what the claims an adapter returns are used for