User Management with AWS Cognito — (1/3) Initial Setup

As a full-stack developer, one of the most critical but challenging parts of building a new application is setting up user management. You need to handle user registration, authentication, password resets, and so much more. Security is paramount, but creating a streamlined onboarding experience is also essential for user adoption.

In the past, you had to build all this functionality from scratch — a time-consuming and error-prone endeavor. Fortunately, AWS Cognito now provides a fully-managed user management solution that takes care of the heavy lifting for you.

In this tutorial, we‘ll do a deep dive on setting up AWS Cognito for a production application. By the end, you‘ll understand the key concepts, how to configure Cognito using best practices, and how to integrate it into your application. Let‘s get started!

What is AWS Cognito?

At its core, AWS Cognito is a service that lets you add user sign-up, sign-in, and access control to your applications. It serves as your user directory, handling all aspects of user management and authentication.

Cognito consists of two main components:

User Pools – A fully-managed user directory that handles user registration, authentication, and account recovery. User pools store your users‘ credentials and metadata.
Identity Pools – Provides temporary AWS credentials to grant your users access to other AWS services like S3 or DynamoDB. Identity pools enable you to use Cognito as an identity provider for authenticated and unauthenticated access to your AWS resources.

User pools are the starting point for adding auth to your app. When a user signs in to your app with their username and password, that request goes to your user pool to verify their credentials. If authentication is successful, Cognito returns a set of JSON Web Tokens (JWTs) that your app can use to verify the user‘s identity and make authenticated requests to your backend.

To grant your users access to AWS resources, you can pass the tokens from your user pool to an identity pool. The identity pool then returns a set of temporary, limited-privilege AWS credentials that your app can use to make requests to other AWS services.

Why Use Cognito for Authentication?

Now you might be wondering – why use Cognito over other auth solutions like Auth0, Okta, or Firebase Authentication? Here are a few key reasons:

Fully-managed service – With Cognito, you don‘t have to worry about standing up auth infrastructure, scaling for traffic spikes, or applying security patches. Cognito handles all of that for you, letting you focus on building your app.
Easy integration with AWS ecosystem – If you‘re already using AWS to host your app backend, databases, file storage, etc, then Cognito offers the deepest integration with those services. You can use IAM roles and policies to govern access to any AWS service based on a user‘s Cognito identity.
Scalability and security out-of-the-box – Cognito is built on AWS‘s battle-tested infrastructure and automatically scales to handle hundreds of millions of users. It provides protection against common threats like DDoS attacks and offers advanced security features like multi-factor authentication (MFA).
Flexible, customizable auth flows – Cognito supports many different auth flows out-of-the-box, like user sign-up and sign-in, password resets, and email/SMS verification. You can easily customize these flows using AWS Lambda triggers to meet your app‘s specific needs.
Cost-effective – Cognito has a generous free tier that covers most small to medium-sized apps. You get 50,000 free active users per month and pay a low per-user fee after that. The paid tier is generally cheaper than Auth0 or Okta for larger apps (assuming you‘re taking advantage of other AWS services as well).

Of course, Cognito isn‘t perfect for every use case. It does require some upfront learning to understand concepts like user pools, identity pools, IAM roles, etc. And if your app is hosted entirely outside of AWS, other auth providers may offer an easier integration path.

However, for most applications running on AWS, Cognito offers unmatched power, flexibility, and ease-of-use for user management. It abstracts away a ton of complexity so you can ship faster and more securely.

Setting Up AWS Cognito

With that background in mind, let‘s walk through the process of setting up AWS Cognito User Pools and Identity Pools for your application.

Step 1 – Create a User Pool

The first step is to create a User Pool in the AWS Cognito console. A user pool represents your app‘s user directory and is where you‘ll define things like password policies, user attributes, and sign-up/sign-in flows.

To create a new user pool:

Navigate to the AWS Cognito console and click "Manage User Pools"
Click "Create a User Pool"
Enter a name for your user pool (e.g. "MyApp-Users")
Select which attributes (email, name, phone number, etc) to collect from users during sign-up
Configure password strength, MFA, and user verification settings
Create an App Client (this represents your application and has permissions to call unauthenticated APIs for sign-up, sign-in, etc)
Review and create the user pool

Here‘s what the user pool creation flow looks like in the AWS Console:

After creating the user pool, take note of its ID (something like us-east-1_abcd1234). You‘ll need this later on when integrating the Cognito SDK into your application.

Step 2 – Configure User Pool Settings

Once your user pool is created, you can further customize its behavior in the user pool settings. Some key things you may want to configure:

Attributes – Add any custom attributes (e.g. "employee ID", "customer type") that are specific to your application in addition to the standard attributes
Policies – Adjust password strength requirements and enable self-service account recovery flows
MFA and verifications – Require MFA during sign-in and customize the email/SMS templates used for new user verification
Message customizations – Tweak the email templates for things like account verification, forgotten password, etc.
App clients – Generate app client secrets for backend applications that will call your user pool APIs
Triggers – Use Lambda functions to customize the behavior of sign-up, sign-in, and authentication flows

I recommend starting simple and only enabling the features you really need. Cognito has a ton of flexibility, but it‘s easy to get overwhelmed. You can always come back and enable more advanced functionality as your app grows.

Step 3 – Create an Identity Pool

The next step is to create a Cognito Identity Pool. Remember, identity pools are what enable your users to access other AWS services with temporary credentials. Even if you don‘t need this functionality right away, it‘s a good idea to create an identity pool upfront so it‘s there when you do need it.

To create an identity pool:

Navigate to the Cognito Federated Identities console
Click "Create new identity pool"
Give your identity pool a name (e.g. "MyApp_IdentityPool")
Choose "Authentication providers" – Select the user pool you created in Step 1
Cognito will automatically create two IAM roles (one for authenticated users and one for unauthenticated users). Attach any desired IAM policies to these roles to grant access to other AWS services.
Review and create the identity pool

Here‘s what that flow looks like in the AWS Console:

After creating the identity pool, note down its ID (something like us-east-1:aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee). You‘ll need to provide this to the Cognito SDKs to facilitate identity pool authorization.

Step 4 – Install the Cognito SDKs

With Cognito configured on the backend, the final step is integrating it into your application code. AWS provides several different SDKs to make this process easier:

Amplify – A set of opinionated client libraries, UI components, and a CLI for building Cognito auth flows quickly. Available for JavaScript, iOS, and Android.
Amazon Cognito Identity SDK for JavaScript – Lower-level JavaScript library for Cognito User Pools. Use this if you want more control over the auth flow than Amplify provides.
AWS SDK for JavaScript – Includes methods for working directly with the Cognito User Pool and Identity Pool APIs. Only use this if you have very custom auth requirements.

For most applications, I recommend starting with Amplify. It provides a nice abstraction layer over the raw Cognito APIs and has pre-built UI components you can drop into your frontend.

Here‘s a quick example of how you would configure the Amplify client in a JavaScript application:

import Amplify from ‘aws-amplify‘;

Amplify.configure({
    Auth: {
        region: ‘us-east-1‘, 
        userPoolId: ‘us-east-1_abcd1234‘,
        userPoolWebClientId: ‘abc123def456ghi789‘,
        identityPoolId: ‘us-east-1:aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee‘
    }
});

And here‘s how you would initiate a user sign-up flow:

import { Auth } from ‘aws-amplify‘;

async function signUp() {
  try {
    const { user } = await Auth.signUp({
      username,
      password,
      attributes: {
          email,          // optional
          phone_number,   // optional - E.164 number convention
      }
    });
    console.log({ user });
  } catch (error) {
    console.log(‘error signing up:‘, error);
  }
}

The Amplify docs have great guides on setting up other common auth flows like sign-in, password reset, and MFA. I highly recommend reading through those as you integrate auth into your application.

Conclusion and Next Steps

And that‘s it! You now have all the pieces in place to add complete user management and authentication to your application. AWS Cognito provides an incredibly powerful and flexible auth solution that can scale with your app, from prototype to production.

In this tutorial, we covered:

The key components of Cognito (User Pools and Identity Pools)
How to set up a User Pool and configure its various settings
Creating an Identity Pool and granting it access to AWS resources
Installing and using the Amplify SDK to add auth flows to your application

If you‘re adding auth to a new or existing application, I highly recommend evaluating Cognito. The initial learning curve pays off in the long run with a battle-tested, scalable, and customizable auth solution.

In the next post, we‘ll dive deeper into common Cognito auth flows and some advanced use cases and customizations. Until then, happy coding!

User Management with AWS Cognito — (1/3) Initial Setup

What is AWS Cognito?

Why Use Cognito for Authentication?