Amazon Cognito (Amplify) - Supabase

Amazon Cognito User Pools (via AWS Amplify or on its own) can be used as a third-party authentication provider alongside Supabase Auth, or standalone, with your Supabase project.

Getting started

First you need to add an integration to connect your Supabase project with your Amazon Cognito User Pool. You will need the pool's ID and region.
Add a new Third-party Auth integration in your project's Authentication settings or configure it in the CLI.
Assign the role: 'authenticated' custom claim to all JWTs by using a Pre-Token Generation Trigger.
Finally setup the Supabase client in your application.

Setup the Supabase client library

typescript

import { fetchAuthSession, Hub } from 'aws-amplify/auth'

const supabase = createClient(
  'https://<supabase-project>.supabase.co',
  'SUPABASE_PUBLISHABLE_KEY',
  {
    accessToken: async () => {
      const tokens = await fetchAuthSession()

      // Alternatively you can use tokens?.idToken instead.
      return tokens?.accessToken
    },
  }
)

// if you're using Realtime you also need to set up a listener for Cognito auth changes
Hub.listen('auth', () => {
  fetchAuthSession().then((tokens) => supabase.realtime.setAuth(tokens?.accessToken))
})

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swift

import Supabase
import AWSPluginsCore

struct UnexpectedAuthSessionError: Error {}

let supabase = SupabaseClient(
  supabaseURL: URL(string: "https://<supabase-project>.supabase.co")!,
  supabaseKey: "SUPABASE_PUBLISHABLE_KEY",
  options: SupabaseClientOptions(
    auth: SupabaseClientOptions.AuthOptions(
      accessToken: {
        let session = try await Amplify.Auth.fetchAuthSession()

        guard let cognitoTokenProvider = session as? AuthCognitoTokensProvider else {
          throw UnexpectedAuthSessionError()
        }

        let tokens = try cognitoTokenProvider.getCognitoTokens().get()
        return tokens.idToken
      }
    )
  )
)

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dart

import 'package:amplify_auth_cognito/amplify_auth_cognito.dart';
import 'package:amplify_flutter/amplify_flutter.dart';
import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';

Future<void> main() async {
  await Supabase.initialize(
    url: 'https://<supabase-project>.supabase.co',
    anonKey: 'SUPABASE_PUBLISHABLE_KEY',
    accessToken: () async {
      final session = await Amplify.Auth.fetchAuthSession();
      final cognitoSession = session as CognitoAuthSession;
      return cognitoSession.userPoolTokensResult.value.accessToken.raw;
    },
  );
  runApp(const MyApp());
}

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kotlin

import com.amplifyframework.auth.AuthSession
import com.amplifyframework.auth.cognito.AWSCognitoAuthSession
import com.amplifyframework.core.Amplify

val supabase = createSupabaseClient(
    "https://<supabase-project>.supabase.co",
    "SUPABASE_PUBLISHABLE_KEY"
) {
    accessToken = {
        getAccessToken()
    }
}

suspend fun getAccessToken(): String? {
    return suspendCoroutine {
        Amplify.Auth.fetchAuthSession(
            { result: AuthSession ->
                val cognitoAuthSession = result as AWSCognitoAuthSession
                it.resume(cognitoAuthSession.userPoolTokensResult.value?.accessToken)
            },
            { _ ->
                // Handle error
            })
    }
}

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Add a new Third-Party Auth integration to your project

In the dashboard navigate to your project's Authentication settings and find the Third-Party Auth section to add a new integration.

In the CLI add the following config to your supabase/config.toml file:

toml

[auth.third_party.aws_cognito]
enabled = true
user_pool_id = "<id>"
user_pool_region = "<region>"

Use a pre-token generation trigger to assign the authenticated role

Your Supabase project inspects the role claim present in all JWTs sent to it, to assign the correct Postgres role when using the Data API, Storage or Realtime authorization.

By default, Amazon Cognito JWTs (both ID token and access tokens) do not contain a role claim in them. If you were to send such a JWT to your Supabase project, the anon role would be assigned when executing the Postgres query. Most of your app's logic will be accessible by the authenticated role.

A recommended approach to do this is to configure a Pre-Token Generation Trigger either V1_0 (ID token only) or V2_0 (both access and ID token). To do this you will need to create a new Lambda function (in any language and runtime) and assign it to the Amazon Cognito User Pool's Lambda Triggers configuration. For example, the Lambda function should look similar to this:

javascript

export const handler = async (event) => {
  event.response = {
    claimsOverrideDetails: {
      claimsToAddOrOverride: {
        role: 'authenticated',
      },
    },
  }

  return event
}

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