Metrics

Gateway and node expose Prometheus text exposition at GET /metrics.

Listener	Default	Env
Gateway /metrics	same as HTTP bind (127.0.0.1:8080)	MOMO_GATEWAY_BIND
Node /metrics	127.0.0.1:9101	MOMO_NODE_METRICS_BIND
Store watch lag	recorded by store adapters	momo_store_watch_lag_seconds

Public binds require MOMO_ALLOW_PUBLIC_BIND=1.

Gateway metrics

Metric	Type	Labels	Meaning
momo_gateway_route_hits_total	counter	—	Host matched a RouteSpec
momo_gateway_route_misses_total	counter	—	Unknown Host (404 path)
momo_gateway_node_connected	gauge	node	1 when gRPC connected + heartbeat fresh
momo_gateway_acquire_duration_seconds	histogram	node, app	Acquire RPC latency
momo_gateway_cold_starts_total	counter	—	Acquire reported cold start
momo_gateway_responses_total	counter	status	Proxied HTTP status (includes 101)
momo_gateway_inflight_requests	gauge	—	Requests currently in flight
momo_gateway_websocket_active	gauge	—	Active upgraded WebSocket bridges
momo_gateway_route_watch_healthy	gauge	—	1 when store route watch is healthy

Node metrics

Metric	Type	Labels	Meaning
momo_node_acquire_total	counter	result (ok/error)	Acquire outcomes
momo_node_release_total	counter	result (ok/error)	Release outcomes

Store metrics

Metric	Type	Meaning
momo_store_watch_lag_seconds	gauge	Seconds since last successfully applied watch event

Structured logging

Set MOMO_LOG_FORMAT=json for one JSON object per line (required in production). Default text is for local development. Honor RUST_LOG for filter levels.

Scrape example

curl -s http://127.0.0.1:8080/metrics   # gateway
curl -s http://127.0.0.1:9101/metrics   # node

Prometheus scrape config sketch:

scrape_configs:
  - job_name: momo-gateway
    static_configs:
      - targets: ["127.0.0.1:8080"]
  - job_name: momo-node
    static_configs:
      - targets: ["127.0.0.1:9101"]