feat: add third-party auth support

src/SupabaseClient.ts

@@ -51,6 +51,7 @@ export default class SupabaseClient<
   protected storageKey: string
   protected fetch?: Fetch
   protected changedAccessToken?: string
+  protected accessToken?: () => Promise<string>
 
   protected headers: Record<string, string>
 
@@ -95,11 +96,24 @@ export default class SupabaseClient<
     this.storageKey = settings.auth?.storageKey ?? ''
     this.headers = settings.global?.headers ?? {}
 
-    this.auth = this._initSupabaseAuthClient(
-      settings.auth ?? {},
-      this.headers,
-      settings.global?.fetch
-    )
+    if (!settings.accessToken) {
+      this.auth = this._initSupabaseAuthClient(
+        settings.auth ?? {},
+        this.headers,
+        settings.global?.fetch
+      )
+    } else {
+      this.accessToken = settings.accessToken
+
+      this.auth = new Proxy<SupabaseAuthClient>({} as any, {
+        get: () => {
+          throw new Error(
+            'Supabase Client is configured with accessToken option, accessing .auth is not possible'
+          )
+        },
+      })
+    }
+
     this.fetch = fetchWithAuth(supabaseKey, this._getAccessToken.bind(this), settings.global?.fetch)
 
     this.realtime = this._initRealtimeClient({ headers: this.headers, ...settings.realtime })
@@ -109,7 +123,9 @@ export default class SupabaseClient<
       fetch: this.fetch,
     })
 
-    this._listenForAuthEvents()
+    if (!settings.accessToken) {
+      this._listenForAuthEvents()
+    }
   }
 
   /**
@@ -241,6 +257,10 @@ export default class SupabaseClient<
   }
 
   private async _getAccessToken() {
+    if (this.accessToken) {
+      return await this.accessToken()
+    }
+
     const { data } = await this.auth.getSession()
 
     return data.session?.access_token ?? null

src/lib/helpers.ts

@@ -54,5 +54,6 @@ export function applySettingDefaults<
       ...DEFAULT_GLOBAL_OPTIONS,
       ...globalOptions,
     },
+    accessToken: options.accessToken ?? undefined,
   }
 }

src/lib/types.ts

@@ -66,6 +66,18 @@ export type SupabaseClientOptions<SchemaName> = {
      */
     headers?: Record<string, string>
   }
+  /**
+   * Optional function for using a third-party authentication system with
+   * Supabase. The function should return an access token or ID token (JWT) by
+   * obtaining it from the third-party auth client library. Note that this
+   * function may be called concurrently and many times. Use memoization and
+   * locking techniques if this is not supported by the client libraries.
+   *
+   * When set, the `auth` namespace of the Supabase client cannot be used.
+   * Create another client if you wish to use Supabase Auth and third-party
+   * authentications concurrently in the same application.
+   */
+  accessToken?: () => Promise<string>
 }
 
 export type GenericTable = {

test/client.test.ts

@@ -7,6 +7,18 @@ const KEY = 'some.fake.key'
 
 const supabase = createClient(URL, KEY)
 
+test('it should create a client with third-party auth accessToken', async () => {
+  const client = createClient(URL, KEY, {
+    accessToken: async () => {
+      return 'jwt'
+    },
+  })
+
+  expect(() => client.auth.getUser()).toThrowError(
+    'Supabase Client is configured with accessToken option, accessing .auth is not possible'
+  )
+})
+
 test('it should create the client connection', async () => {
   expect(supabase).toBeDefined()
   expect(supabase).toBeInstanceOf(SupabaseClient)