Module shield 

Shield: request rate limiting.

The proxy runs embedded on each service instance, so every decision is made locally with a per-instance GCRA shaper (store::GcraStore) that adds no blocking latency to the request path. When a shared store is configured, a background task reconciles counters across instances asynchronously to approximate a fleet-wide limit; the request path never blocks on it.

A request is limited by the first rule whose glob matches its path. The rule’s key selects who is limited (client IP, a header value, or a validated JWT claim) and its profile selects how much.

Modules

gcra

GCRA (Generic Cell Rate Algorithm) rate limiter core.

global

Cross-instance reconciliation of the fleet-wide limit view via a shared store.

matcher

Compile Shield config into runtime matchers, limiters, and rules.

rate

Rate-limit rate parsing.

resolve

Limit resolution: derive a key’s {rate, burst} from the JWT itself or from an external service, on top of the static config profiles.

store

In-process GCRA state store.

window

Sliding-window counter math for the global (cross-instance) limit view.

Structs

Shield

Compiled Shield rules, limit tiers, and the local GCRA store.

Functions

post_auth_middleware

Post-auth middleware: enforces rules keyed by a validated JWT claim. Layered inside auth so the verified claims are available on the request.

pre_auth_middleware

Pre-auth middleware: enforces rules that need no validated claims (IP / header keys). Layered outside auth so anonymous floods are shed before any signature verification.