The idea that AWS's services are fully regionalized or isolated has always been a myth.
All the identity and access services for the public cloud outside of China (aka "IAM for the aws partition" to employees) are centralized in us-east-1. This centralization is essentially necessary in order to have a cohesive view of an account, its billing, and its permissions.
And IAM is not a wholly independent software stack: they rely on DynamoDB and a few other services, which in turn have a circular dependency on IAM.
During us-east-1 outages it's sometimes possible to continue using existing auth tokens or sessions in other regions, while not possible to grant new ones. When I worked there, I remember at least one case where my team's on-calls were advised not to close ssh sessions or AWS console browser tabs, for fear that we'd be locked out until the outage was over.
All the identity and access services for the public cloud outside of China (aka "IAM for the aws partition" to employees) are centralized in us-east-1. This centralization is essentially necessary in order to have a cohesive view of an account, its billing, and its permissions.
And IAM is not a wholly independent software stack: they rely on DynamoDB and a few other services, which in turn have a circular dependency on IAM.
During us-east-1 outages it's sometimes possible to continue using existing auth tokens or sessions in other regions, while not possible to grant new ones. When I worked there, I remember at least one case where my team's on-calls were advised not to close ssh sessions or AWS console browser tabs, for fear that we'd be locked out until the outage was over.