serverinterceptors

itemWhat a peer must prove before its call runs. The framework owns the seam and not the scheme: a token check over redis, a signed request, an mTLS peer identity — each is an implementation of this trait, so the interceptor never grows a branch per mechanism.

fnThe server tracing interceptor: open a server span for the call, as a child of the context the client sent, and record the resulting status on it.

fnThe recovery interceptor: an error raised anywhere below is reported as Internal instead of reaching the transport, and logged with its method so the reason is not lost. A handler itself cannot raise — the transport hands it a request and takes back bytes — but a layer added below can.

structWhat the stat interceptor logs: the slow-call threshold, and the methods whose payload must not reach a log line.

fnThe default stat policy: half a second counts as slow, and every payload is logged.

fnThe stat interceptor: every call is timed, and a slow one is logged with its method. A method in ignore_content_methods is logged without the payload size, so a credential never reaches a log file.

fnThe server Prometheus interceptor: time the call and count it under its method and status code.

fnThe server breaker interceptor: a shed call never reaches the handler and answers Unavailable. A deadline or a shed on the way in says nothing about this service, so it does not count as a failure.

fnThe shedding interceptor: a call is admitted against the adaptive shedder, and refused with ResourceExhausted when the machine is past its threshold. A refused call is reported to the shedder as a drop; an admitted one is reported by how it ended.

structA per-method deadline: path gets budget_ms instead of the service's.

fnThe timeout interceptor: a call that ran past its budget is reported as DeadlineExceeded. methods overrides the service budget for named paths. The deadline is checked when the handler returns, not raced against a timer: this transport runs the peer in the caller's task, so there is no frame to abandon. A socket-backed server hands the same budget to its read deadline, which does preempt.

fnThe authentication interceptor: a peer that cannot prove itself is refused with Unauthenticated and its call never reaches the handler. It runs outermost, ahead of the breaker and the metric families, so a stream of unauthenticated calls cannot push the breaker open or fill the counters with traffic the service never served.

structEverything the server chain needs that is not a flag.

fnThe dependencies for a server config, with every seam at its default: a system clock, a discarding tracer, a fresh breaker and shedder, and no authenticator — a server that does not say who may call it accepts anybody, which is what Auth: false means.

fnThe server chain conf asks for, outermost first: authentication, tracing, recovery, the stat log, the metric families, the breaker, shedding and the deadline.