Change API Rate Limits and Circuit Breakers at Runtime — No Java Redeploy (Kiponos SDK)

An incident at 3 AM is the wrong time to discover your rate limits are in application.yml. You need to throttle a noisy tenant, open a circuit on a failing downstream, or raise limits for a launch partner — without rolling pods.

Kiponos.io gives Java API services live rate-limit and circuit-breaker config: WebSocket deltas into an in-memory SDK cache, local reads on every request.

The hot-path constraint

if (breaker.isOpen("payments-svc")) {
    return Response.status(503).entity("degraded").build();
}
if (rateLimiter.exceeded(tenantId)) {
    return Response.status(429).entity("slow down").build();
}

These checks run on every request. Polling Redis or a config service per call adds milliseconds and failure modes. Static YAML means redeploy during an outage.

Kiponos pattern: connect once, read kiponos.path("limits", tenantId).getInt("rpm") from local memory.

Config tree example

limits/
  default/
    rpm: 1200
    burst: 200
  tenant_acme/
    rpm: 5000
    burst: 800
breakers/
  payments-svc/
    failure_threshold: 0.5
    open_seconds: 30
    half_open_requests: 5
  inventory-svc/
    failure_threshold: 0.3
    open_seconds: 60

Spring Boot filter integration

@Service
public class LiveGatewayPolicy {
    private final Kiponos kiponos = Kiponos.createForCurrentTeam();

    public boolean allow(String tenantId) {
        var node = kiponos.path("limits", tenantIdOrDefault(tenantId));
        int rpm = node.getInt("rpm");
        return localRpmCounter(tenantId).tryAcquire(rpm);
    }

    public int breakerOpenSeconds(String downstream) {
        return kiponos.path("breakers", downstream).getInt("open_seconds");
    }
}

Ops changes tenant_acme.rpm in the dashboard → next request sees it. No restart.

Incident scenarios

Event	Action in Kiponos UI
Tenant abuse	Lower `rpm` for that tenant
Downstream melting	Raise `failure_threshold` or increase `open_seconds`
Product launch	Bump partner tenant limits live
Recovery	Close breaker config / restore defaults