Reducing Control Plane Dependencies in US-EAST-1: A Practical Guide for AWS Customers

Background: Understanding the US-EAST-1 Challenge

US-EAST-1 (Northern Virginia) hosts the control planes for numerous global AWS services. While AWS has designed these services with separation between control planes and data planes to achieve static stability, the concentration of global service control planes in this region means that customers need to understand how to architect their workloads to minimize dependencies on these control planes, particularly in their recovery paths.

Why This Matters

A critical architectural principle: If your recovery strategy has a dependency on control plane operations, an availability impact to the control plane or the Region hosting the control plane will reduce your chances of successful recovery.

The key insight is that control plane impairments don't necessarily affect running workloads—data planes continue to operate. However, recovery plans that depend on control plane operations (creating, updating, or deleting resources) can fail when you need them most.

The Core Problem: Control Plane vs. Data Plane

AWS separates most services into control plane and data plane concepts:

Control Planes provide the administrative APIs used to create, read/describe, update, delete, and list (CRUDL) resources. Control planes tend to be complicated orchestration and aggregation systems. For example: launching a new EC2 instance, creating an S3 bucket, or updating an IAM policy.

Data Planes provide the primary function of the service. Data planes are intentionally less complicated with fewer moving parts compared to control planes. This makes failure events statistically less likely to occur in the data plane versus the control plane. For example: a running EC2 instance, reading/writing to an S3 bucket, or IAM authentication and authorization.

Critical principle: Data plane access to resources, once provisioned, has no dependency on the control plane, and therefore is not affected by any control plane impairment. Even if the ability to create, modify, or delete resources is impaired, existing resources remain available.

Global Services with US-EAST-1 Control Plane Dependencies

The following are partitional services and their control plane location in the aws partition:

AWS IAM (us-east-1)

AWS Organizations (us-east-1)

AWS Account Management (us-east-1)

Route 53 Application Recovery Controller (ARC) (us-west-2) - This service is only present in the aws partition

AWS Network Manager (us-west-2)

Route 53 Private DNS (us-east-1)

Additionally, certain S3 control plane operations (like PutBucketCors, PutBucketReplication, PutBucketLifecycle) have underlying dependencies on us-east-1, and all CreateBucket/DeleteBucket operations depend on us-east-1 for global name uniqueness validation.

The Solution: Static Stability

Static stability is the most effective strategy for reducing control plane dependencies.

Static stability definition: Systems operate in a static state and continue to operate as normal without the need to make changes during the failure or unavailability of dependencies. Ref- https://docs.aws.amazon.com/whitepapers/latest/aws-fault-isolation-boundaries/static-stability.html

"The most reliable recovery and mitigation mechanisms are the ones that require the fewest changes to achieve recovery. Instead of relying on the EC2 control plane to launch new EC2 instances to recover from a failed Availability Zone, having that extra capacity pre-provisioned helps achieve static stability."

Key principle: Eliminating dependencies on control planes (the APIs that implement changes to resources) in your recovery path helps produce more resilient workloads.

Practical Strategies to Reduce Dependencies

1. Pre-Provision All Critical Resources

Guidance: "Do not rely on creating, updating, or deleting resources that require the creation, updating, or deletion of Route 53 resource records, hosted zones, or health checks in your recovery path. Pre-provision these resources, like ELBs, to prevent a dependency on the Route 53 control plane in your recovery path."

Several AWS services depend on the Route 53 control plane in us-east-1 to create DNS records when you provision resources:

• Amazon API Gateway REST and HTTP APIs
• Amazon ELB load balancers
• AWS PrivateLink VPC endpoints
• AWS Lambda URLs
• Amazon ElastiCache
• Amazon OpenSearch Service
• Amazon RDS
• Amazon EKS Kubernetes control plane

Recommendation: Pre-provision all these resources before you need them for recovery to avoid control plane dependencies.

2. Implement IAM Best Practices

Break-Glass Users:

"A statically-stable design for a 'break-glass' admin user would be to create a user with the appropriate permissions attached, have the password set and the access key and secret access key provisioned, and then lock those credentials in a physical or virtual vault. When required during an emergency, retrieve the user credentials from the vault and use them as needed."

Non-statically-stable approach: "A non-statically-stable design would be to provision the user during a failure, or having the user pre-provisioned, but only attaching the admin policy when required. These approaches would depend on the IAM control plane."

Regional STS Endpoints:

STS usage from the AWS SDK and CLI defaults to us-east-1. The STS service also provides Regional endpoints.

Recommendation: "Update your SDK and CLI configuration to use the Regional STS endpoints" by following the directions at AWS STS Regionalized endpoints.

3. Leverage Data Plane Operations for Failover

Route 53:

"The Route 53 control plane consists of all public Route 53 APIs covering functionality for hosted zones, records, health checks, DNS query logs, reusable delegation sets, traffic policies, and cost allocation tags. It is hosted in us-east-1. The data plane is the authoritative DNS service, which runs across over 200 PoP locations as well as in each AWS Region, answering DNS queries based on your hosted zones and health check data."

Recommended approach: "A statically-stable design would be to use the status of health checks to perform failovers between Regions or to evacuate an Availability Zone. You can use Route 53 Application Recovery Controller (ARC) routing controls to manually change the status of health checks and alter the responses to DNS queries."

Non-statically-stable approach: "A non-statically-stable design would be to update the value of a Route 53 resource record via the ChangeResourceRecordSets API, change the weight of a weighted record, or create new records to perform failover. These approaches depend on the Route 53 control plane."

CloudFront:

"The CloudFront control plane consists of all public CloudFront APIs for managing distributions, and is hosted in us-east-1. The data plane is the distribution itself served from the PoPs in the edge network."

Recommended approach: "A statically-stable design would be to use automated origin failovers to mitigate the impact from an impairment to one of your origins."

Non-statically-stable approach: "A non-statically-stable design would be to manually update the configuration of your distribution in response to an origin failure. This approach would depend on the CloudFront control plane."

4. IAM Identity Center:

"Identity Center is a cloud-based service that makes it easy to centrally manage single sign-on access to a customer's AWS accounts and cloud applications. Identity Center must be deployed in a single Region of your choosing. However, the default behavior for the service is to use the global SAML endpoint (https://signin.aws.amazon.com/saml), which is hosted in us-east-1.“

Recommendation: "If you have deployed Identity Center into a different AWS Region, you should update the relaystate URL of every permission set to target the same Regional console endpoint as your Identity Center deployment. For example, if you deployed Identity Center into us-west-2, you should update the relaystate of your permissions sets to use https://us-west-2.console.aws.amazon.com. This will remove any dependency on us-east-1 from your Identity Center deployment.“

Additionally: "Create a break-glass user(s) in case your IAM Identity Center deployment is unavailable."

SAML Sign-in:

"SAML services exist in all AWS Regions. To use this service, choose the appropriate regional SAML endpoint, like https://us-west-2.signin.aws.amazon.com/saml.“

Recommendation: "Update your IAM role trust policies to accept SAML logins from multiple Regions. During a failure, update your IdP configuration to use a different Regional SAML endpoint if your preferred endpoint is impaired. Create a break-glass user(s) in case your IdP is impaired or unavailable."

5. Handle S3 Dependencies

The following Amazon S3 control plane operations have an underlying dependency on us-east-1 in the AWS partition:

• PutBucketCors, DeleteBucketCors
• PutAccelerateConfiguration
• PutBucketRequestPayment
• PutBucketObjectLockConfiguration
• PutBucketTagging, DeleteBucketTagging
• PutBucketReplication, DeleteBucketReplication
• PutBucketEncryption, DeleteBucketEncryption
• PutBucketLifecycle, DeleteBucketLifecycle
• PutBucketNotification
• PutBucketLogging, DeleteBucketLogging
• PutBucketVersioning
• PutBucketPolicy, DeleteBucketPolicy
• PutBucketOwnershipControls, DeleteBucketOwnershipControls
• PutBucketAcl
• PutBucketPublicAccessBlock, DeleteBucketPublicAccessBlock

"Amazon S3 bucket names are globally unique and all calls to the CreateBucket and DeleteBucket APIs depend on us-east-1, in the aws partition, to ensure name uniqueness, even though the API call is directed at the specific Region in which you want to create the bucket."

Recommendation: "Do not rely on deleting or creating new S3 buckets or updating S3 bucket configurations as part of your recovery path. Pre-provision all required S3 buckets with the necessary configurations so that you do not need to make changes in order to recover from a failure."

6. Design Multi-AZ Architectures with Static Stability

"One of the failure modes you should plan for with Multi-Availability Zone architectures is the loss of an Availability Zone, which can result in the loss of an Availability Zone's worth of capacity. If you haven't pre-provisioned enough capacity to handle the loss of an Availability Zone, this could result in your remaining capacity being overwhelmed by the current load."

Example: "During normal operation, let's assume your workload requires six instances to serve customer traffic across three Availability Zones. To be statically-stable against a single Availability Zone failure, you would deploy three instances in each Availability Zone, for a total of nine. If a single Availability Zone-worth of instances failed, you would still have six left and be able to continue to serve your customer traffic without the need to provision and configure new instances during the failure."

Cost consideration: "Achieving static stability for your EC2 capacity has additional cost, since, in this case, you are running 50% additional instances. Not all services where you can pre-provision resources will incur additional cost, such as pre-provisioning an S3 bucket or a user. You will need to weigh any trade-offs of implementing static stability against the risk of exceeding the desired recovery time for your workload."

7. Cache Control Plane Data

Recommendation: "If you require the data from a control plane operation for recovery, cache this data in a data store that can be accessed through its data plane, like an AWS Systems Manager Parameter Store (SSM Parameter Store) parameter, a DynamoDB table, or an S3 bucket. For redundancy, you may also choose to store that data in an additional Region."

Example: "Following the best practices for Route 53 Application Recovery Controller (ARC), you should hardcode or bookmark your five Regional cluster endpoints. During a failure event, you might not be able to access some API operations, including Route 53 ARC API operations that are not hosted on the extremely reliable data plane cluster. You can list the endpoints for your Route 53 ARC clusters by using the DescribeCluster API operation."

Common Anti-Patterns to Avoid

These common misconfigurations or anti-patterns introduce dependencies on global services' control planes:

1. Making changes to Route 53 records, like updating an A record's value or changing a weighted record set's weights, to perform failover
2. Creating or updating IAM resources, including IAM roles and policies, during a failover (typically not intentional, but might be a result of an untested failover plan)
3. Relying on IAM Identity Center for operators to gain access to production environments during a failure event
4. Relying on the default IAM Identity Center configuration to utilize the console in us-east-1 when you have deployed Identity Center into a different Region
5. Making changes to AGA traffic dial weights to manually perform a Regional failover
6. Updating a CloudFront distribution's origin configuration to fail away from an impaired origin
7. Provisioning disaster recovery (DR) resources, like ELBs and RDS instances during a failure event, that depend on creating DNS records in Route 53

Implementation Checklist

Immediate Actions

• [ ] Configure AWS CLI/SDK to use regional STS endpoints
• [ ] Create and secure break-glass IAM users with full credentials provisioned
• [ ] Audit current failover procedures for control plane dependencies
• [ ] Document all resources that would need to be created during recovery

Short-term Improvements

• [ ] Pre-provision all ELBs, RDS instances, and other resources that create Route 53 DNS records
• [ ] Configure Route 53 health checks and automated failover routing policies
• [ ] Set up CloudFront origin groups with automatic origin failover
• [ ] Update IAM Identity Center relay state URLs to match deployment region (if applicable)
• [ ] Configure regional SAML endpoints in IAM role trust policies
• [ ] Pre-provision all S3 buckets with necessary configurations (CORS, lifecycle, replication, etc.)

Long-term Strategy

• [ ] Implement static stability across all critical workloads
• [ ] Test recovery procedures to ensure no control plane dependencies
• [ ] Cache critical control plane data in data plane services (SSM Parameter Store, DynamoDB, S3)
• [ ] Pre-provision extra capacity for Multi-AZ architectures to handle AZ failures
• [ ] Hardcode or bookmark Route 53 ARC cluster endpoints (if using ARC)

Testing Your Resilience

"You need to practice the failover to know that it will work when you need it."

To validate your static stability implementation:

1. Test recovery procedures - Execute your recovery plan to ensure it works without control plane access
2. Verify data plane operations - Confirm all critical functions work with existing, pre-provisioned resources
3. Identify dependencies - Document any remaining control plane dependencies discovered during testing
4. Iterate and improve - Refine your approach based on test results

Conclusion

"AWS provides several different constructs for fault isolation boundaries. You should consider how you architect for zonal, Regional, and global services as well as the potential impacts on your workload and your workload's ability to recover during control plane impairments. Static stability is one of the primary ways that you can avoid control plane dependencies and create reliable and resilient HA and DR mechanisms when you use AWS services."

Core message: The most reliable recovery and mitigation mechanisms are the ones that require the fewest changes to achieve recovery.

By understanding the distinction between control planes and data planes, and by implementing static stability patterns, you can build workloads that remain resilient even during control plane impairments in us-east-1 or any other region.

Additional Resources

• AWS Fault Isolation Boundaries Whitepaper

• AWS Well-Architected Framework - Reliability Pillar

• Static Stability Using Availability Zones - Amazon Builders' Library

• Advanced Multi-AZ Resilience Patterns

This blog post is based on the AWS Fault Isolation Boundaries whitepaper and represents best practices for building resilient architectures on AWS. Always test your specific implementation and consult AWS documentation for the latest guidance.