As a developer advocate working with web and mobile application developers, I’ve often heard about the need to maintain consistent user authentication in the unlikely event of a regional service interruption. The increasing use of agentic AI, microservices, automation, and service accounts has sparked a similar need for machine-to-machine authentication. Today, I’m excited to share two important updates to Amazon Cognito: multi-Region replication for improved resilience, and support for customer managed keys for more control encryption control.

Many applications rely on Amazon Cognito to handle user and machine-to-machine authentication, and to manage user profiles. When building for high availability, having consistent data across different AWS Regions is a key approach, and until now, achieving that consistency came with significant challenges. Engineering teams spent significant time building and maintaining custom replication solutions to synchronize configurations across Regions. Manual export and import of user data between Regions created security risks from potential data exposure and introduced opportunities for data inconsistencies. During regional transitions, end users experienced disruptions like forced password resets and re-authentication. For machine-to-machine communications, teams had to create new app clients in the secondary region, which meant reconfiguring their applications and updating OAuth-protected resources to accept access tokens issued by the new regional issuer. These challenges made it difficult to maintain uninterrupted operations across Regions.

With multi-Region replication, Amazon Cognito automatically maintains a synchronized copy of your user data and machine secrets in a secondary AWS Region of your choice. The replication flows in one direction, from your primary Region to the secondary Region. This includes user profiles, credentials, and pool configurations. The secondary Region operates in read-only mode, focusing on maintaining authentication capabilities. Existing sessions continue uninterrupted.

When you need to direct traffic to the secondary Region, your existing users can continue signing in with their existing credentials without disruption, and currently signed-in users remain authenticated because both regions recognize access tokens issued by either region. Multi-Region replication supports all authentication methods, including federated sign-in through social providers (Amazon, Google, Apple, Facebook), Security Assertion Markup Language (SAML) and OpenID Connect (OIDC) integrations, and API authorization flows. This approach maintains availability for both customer-facing applications and machine-to-machine communications in your backend services. While authentication continues without interruption, operations like new user registration or profile updates are not available during failover.

Before configuring multi-Region replication, you must configure a multi-Region customer managed key stored in AWS Key Management Service (AWS KMS) to encrypt your user data at rest. These keys provide consistent encryption across Regions while giving you control over your encryption strategy.

How this works in practice
I start this demo with an existing Cognito user pool in the us-west-2 (Oregon) Region. I want to configure replication to us-east-1 (Northern Virginia). I also have a customer managed key replicated in these two Regions.

Configuring multi-Region replication is just three steps. The AWS Management Console guides me through the steps: set up a custom key for encryption, configure multi-region OIDC endpoints, and configure the replication itself.

First, I set up a custom AWS KMS key to encrypt the data at rest.

I select the custom key I created. I also update the key policy to allow Amazon Cognito to access and use the key. The console shows the correct IAM policy statements to add to my key policy.

The console confirms when the custom key is selected and correctly configured.

Second, I follow the console instructions to configure the OIDC issuer type. On Step 2 – optional, I choose Configure.

I make sure to update my client applications with these new endpoints. This is a required change that will need a redeployment of server-side applications and an update submission for mobile apps on the App Store and Google Play. If I don’t update the endpoints, my users will experience disruptions because requests to the old endpoints will no longer be routed correctly.

On the next screen, I select Updated. I take note of the new URLs. I confirm the changes and choose Change issuer type.

Finally, I select the target Region for replication. Only Regions where the custom encryption key is replicated are available for selection. After having chosen the target Region, I choose Create..

The service prepares the replication. The time needed depends on the amount of data in the user pool.

When the replicated user pool is ready, I manually Activate it.

The replication status becomes Active. It is ready to direct traffic to the replica.

Additional configurations
The console helps me to keep track of additional configurations I have to plan. When I’m using Lambda functions for custom authentication flows or SMS or email notifications, I must also deploy and configure these resources in the new Region.

Similarly, log streaming or AWS WAF configuration must be manually configured in the target Region before I start directing authentication traffic to it.

Health checks and failover
Both primary and secondary regional endpoints remain active and ready to serve your traffic at all times. To monitor system health and manage failovers, you design a strategy that aligns with your application’s specific requirements and security posture. You can implement health checks to monitor the status of authentication services in your primary Region and define criteria for when to initiate failover. These checks might look for error rates, latency patterns, or specific service alerts.

When your monitoring system detects issues meeting your failover criteria, you can redirect traffic to the secondary Region through DNS updates. This approach gives you control over the failover process while maintaining security. Consider testing your failover strategy during off-peak hours by redirecting a small portion of traffic to verify that authentication continues working as expected in the secondary Region.

When using managed login and federation with custom domains, you can also use the built-in traffic routing feature by providing an Amazon Route 53 health check ID.

Pricing and availability
Multi-Region replication is available today as an add-on feature for Amazon Cognito customers using Essentials and Plus tier. For user authentication, the add-on costs $0.0045 per monthly active user per replica Region for Essentials tier customers and $0.006 per monthly active user per replica region for Plus tier customers. For machine-to-machine (M2M) authentication, the add-on is a 30% charge on top of the standard volume-based pricing for successful tokens issued. For detailed pricing information, see Amazon Cognito pricing.

Multi-Region replication is available in the following Regions: US East (Ohio, N. Virginia), US West (N. California, Oregon), Asia Pacific (Mumbai, Seoul, Singapore, Sydney, Tokyo), Canada (Central), Europe (Frankfurt, Ireland, London, Paris, Stockholm), and South America (São Paulo).

Any of these Regions can be used as the source or the destination for the replication.

Support for customer managed keys is available for the Essentials and Plus tiers. It is available in the following Regions: US East (Ohio, N. Virginia), US West (N. California, Oregon), Africa (Cape Town), Asia Pacific (Hong Kong, Hyderabad, Jakarta, Malaysia, Melbourne, Mumbai, New Zealand, Osaka, Seoul, Singapore, Sydney, Thailand, Tokyo), Canada (Central), Canada West (Calgary), Europe (Frankfurt, Ireland, London, Milan, Paris, Spain, Stockholm, Zurich), Israel (Tel Aviv), Mexico (Central), South America (São Paulo), and AWS GovCloud (US-East, US-West)

From my conversations with customers, maintaining business continuity during regional incidents while meeting security requirements is a high priority. Multi-Region replication provides the capability to build more resilient applications without managing complex replication logic yourself. The automatic synchronization of user data and configurations reduces operational overhead while maintaining security.

For customers in regulated industries, the new support for customer managed keys provides additional control over data encryption. You can now use your own encryption keys to protect user data at rest, helping you meet regulatory requirements in industries like healthcare and financial services.

To get started with multi-Region replication and customer managed key encryption, visit the Amazon Cognito console or see the documentation for detailed setup instructions. I look forward to hearing how you use this feature to strengthen your application architecture.

— seb