gate: Detect disconnected inner services in readiness#2491
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If `Gate` becomes ready, it assumes the inner service remains ready indefinitely. Load balancers rely on lazy and redudant readiness checking to avoid disconnected endpoints. This change fixes the Gate to ensure that the inner service is always polled whenever the gate is polled.
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It looks like this behavior was specifically added in 172523f. Based on my reading of that commit message, it seems like this change fixes this by dropping the stored permit. |
hawkw
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Oct 25, 2023
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| // If we previously polled to ready and acquired a permit, clear it so | ||
| // we can reestablish readiness without holding it. | ||
| self.permit = Poll::Pending; |
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thanks for the comment, this makes sense to me.
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| #[tokio::test] | ||
| async fn gate_repolls_back_to_pending() { |
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i think this behavior is complex enough that it would be nice to have a comment here explaining what specific properties we are testing for here?
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olix0r
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Nov 2, 2023
This release includes several bugfixes. Notably, inbound proxies would not properly reflect grpc-status in metrics by default. Furthermore, proxies now long warnings when they receive unexpected error responses from the control plane. --- * chore: change `rust-toolchain` file to toml format (linkerd/linkerd2-proxy#2487) * gate: Detect disconnected inner services in readiness (linkerd/linkerd2-proxy#2491) * Bump ahash to v0.8.5 (linkerd/linkerd2-proxy#2498) * gate: Fix readiness deadlock (linkerd/linkerd2-proxy#2493) * Log a warning when the controller clients receive an error (linkerd/linkerd2-proxy#2499) * inbound: Fix gRPC response classification (linkerd/linkerd2-proxy#2496) Signed-off-by: Oliver Gould <[email protected]>
olix0r
added a commit
to linkerd/linkerd2
that referenced
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Nov 2, 2023
This release includes several bugfixes. Notably, inbound proxies would not properly reflect grpc-status in metrics by default. Furthermore, proxies now long warnings when they receive unexpected error responses from the control plane. --- * chore: change `rust-toolchain` file to toml format (linkerd/linkerd2-proxy#2487) * gate: Detect disconnected inner services in readiness (linkerd/linkerd2-proxy#2491) * Bump ahash to v0.8.5 (linkerd/linkerd2-proxy#2498) * gate: Fix readiness deadlock (linkerd/linkerd2-proxy#2493) * Log a warning when the controller clients receive an error (linkerd/linkerd2-proxy#2499) * inbound: Fix gRPC response classification (linkerd/linkerd2-proxy#2496) Signed-off-by: Oliver Gould <[email protected]>
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If
Gatebecomes ready, it assumes the inner service remains ready indefinitely.Load balancers rely on lazy and redudant readiness checking to avoid disconnected endpoints.
This change fixes the Gate to ensure that the inner service is always polled whenever the gate is polled.