Retry IAM calls on throttling in RuntimeSupport integration tests#2458
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The RuntimeSupport integration tests now run in parallel, and each test class provisions its own IAM role (GetRole/CreateRole/AttachRolePolicy at startup, ListAttachedRolePolicies/DetachRolePolicy/DeleteRole at teardown). The IAM control-plane APIs have low request-rate limits, so the parallel burst intermittently throttles with 'Rate exceeded', failing TestAllNET10HandlersAsync and TestThreadingLogging in setup rather than on any assertion. Wrap the IAM calls in a throttle-aware retry with exponential backoff so the parallel startup/teardown burst is smoothed instead of failing.
GarrettBeatty
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Release Not Needed
normj
approved these changes
Jul 2, 2026
philasmar
approved these changes
Jul 6, 2026
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Problem
The
Run Tests on AWSCodeBuild step has been intermittently failing (e.g. run 28538095638) with 2 of 24 tests failing inAmazon.Lambda.RuntimeSupport.IntegrationTests:CustomRuntimeNET10Tests.TestAllNET10HandlersAsyncCustomRuntimeAspNetCoreMinimalApiCustomSerializerTest.TestThreadingLoggingBoth fail identically during test setup, not on any assertion:
Root cause
The integration tests now run in parallel (#2451). Each test class uses a unique function name and sets
ExecutionRoleName = FunctionName, so every test provisions its own IAM role —GetRole/CreateRole/AttachRolePolicyat startup andListAttachedRolePolicies/DetachRolePolicy/DeleteRoleat teardown. IAM's control-plane APIs have low request-rate limits, so the concurrent burst intermittently throttles withRate exceeded, and the SDK's default retries aren't enough under this contention.Fix
Wrap the IAM calls in
BaseCustomRuntimeTestwith a throttle-aware retry (exponential backoff, 2s → capped 30s, up to 8 attempts). This smooths the parallel startup/teardown burst instead of failing the test. Throttling is detected via HTTP 429, throttle-family error codes, and theRate exceededmessage.Follows the test-stabilization theme of #2451. Test-only change — no shipped package affected, so no change file (matching #2451).