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AWS IAM is designed with a control plane / data plane dichotomy. Even if the control plane is completely dead and all API requests are failing, services in a st
by electroly 5y ago
AWS IAM is designed with a control plane / data plane dichotomy. Even if the control plane is completely dead and all API requests are failing, services in a steady-state (i.e. not responding to changes via API calls) can still rely on IAM roles using their cached information. For example, in the recent us-east-1 outage when you couldn't start new services because IAM checks would fail, existing EC2 instances that rely on IAM instance profiles to access services like S3 could still do so even though IAM was down.
- spmurrayzzz 5y agoI was gonna respond with the same commentary here. That has been my experience beyond just IAM controls and why I advocate for passive systems for critical workloads. Sometimes this _can_ be costly. For example with something like autoscaling, thats an active system I've seen fail when seemingly unrelated systems are failing. The result is scaling out systems intentionally ahead of time to deal with oversubscription or burst traffic which can leave you with (costly) idle compute. I don't mind this tradeoff personally, but can understand that budget constraints are going to be different org to org.