The per-pod semaphore was not a cap: 3 replicas x 4 slots advertised 12
concurrent requests while the engine runs 4, and nothing coordinated the
replicas. Admission is now gated on the engine's own published gauges,
which is global by construction because every replica contends for the
same engine.
- new internal/proxy/engine_state.go: 2s scrape of the backend /metrics,
hand-rolled exposition parse (no new dependency), unhealthy after 3
consecutive failed polls, and a startup self-check that raises
observer_degraded rather than falling back to fail-open silently
- gate: park while kv_cache_usage_perc >= 0.90 or running + waiting >=
ADMISSION_MAX_INFLIGHT, bounded by ADMISSION_MAX_PARK_SECONDS, then
503 + Retry-After: 5. Unknown state fails open on purpose
- streaming requests receive SSE keep-alive heartbeats while parked
- router: extract only the top-level model field instead of unmarshalling
the whole body into a map; body cap from MAX_BODY_BYTES (1 MiB, the
model path previously inherited the 100 MB default)
- GOMAXPROCS from the cgroup CPU quota: the container is limited to 500m
while Go defaulted to the host core count and was CFS-throttled
- VLLM_MAX_QUEUE_DEPTH default 20 -> 8
- delete k8s/configmap.yaml: absent from kustomization.yaml, and the live
ConfigMap of that name carries an unrelated key
- correct the llm-client NetworkPolicy comment; llm-serving-ingress now
selects by namespace, not by that label
Observers run only for models named in ADMISSION_OBSERVE_MODELS.
reasoning is the only vLLM engine here; ornith and qwen-cpu are Ollama
and embeddings/rerank are TEI, none of which publish vllm:* series, so
observing them would hold observer_degraded at 1 permanently.
Companion change (engine flags + dashboard panels) is
riotpiao-poimen/homelab#51.
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