`retry_back_off.max_interval` is used as per-try timeout for gRPC services (`core`) retry strategy
#38.847 aperta il 21 mar 2025
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Title: Back-off retry_back_off.max_interval is used as per-try timeout for gRPC services (core) retry strategy
Description:
We noticed that when using ext_authz filter with retry_policy configured for gRPC service, our service requests were timing out rather quickly. Turned out that retry_back_off.max_interval is actually used as per-try timeout when core retry policy is converted to route retry policy.
Here we convert config.core.v3.RetryPolicy retry policy to config.route.v3.RetryPolicy retry policy for gRPC service and that function uses retry_back_off.max_interval to populate per-try timeout here.
I think we should add dedicated per-try timeout configuration to the core retry policy and use that instead.
Repro steps:
Define an ext_authz filter using gRPC service and configure retry_back_off.max_interval set to very low value, like 1 or 2 millisecond. Make sure you have retry_back_off.base_interval set lower than the max_interval.
Make a request through Envoy that hits the filter and observe it time out.