Reference — Metrics

The UNS bridge emits relay metrics through the EdgeCommons metric service. With metricEmission.target: messaging, metrics are published on the reserved UNS metric class:

ecv1/{device}/uns-bridge/main/metric/{metricName}

The bridge originates its own metrics on the device bus and then relays them to the site broker like other device traffic. It also forwards other components’ metric messages. This page describes only the bridge’s own custom non-system metrics.

Dimension model

The bridge’s metric measures encode UNS class or scalar counter names instead of adding per-class CloudWatch dimensions. Runtime-injected component dimensions identify the bridge component and device.

No topic, reply topic, endpoint, or error text is used as a metric dimension. Use logs and events for those high-cardinality diagnostics.

Emission model

Counters emit interval deltas. Gauges emit the current value. Deltas are saturating, so a process restart or counter reset never produces a negative value.

Per-class metrics use one measure per relayed class: state, cfg, evt, metric, data, log, and app.

Per-class relay metrics

Dimensions: runtime-injected component dimensions only.

Metric	Measures	Unit	Purpose
relay_uplinked	state, cfg, evt, metric, data, log, app	Count	Messages successfully relayed from device bus to site broker by class. Helps verify which traffic classes are crossing the bridge.
relay_dropped_disabled	state, cfg, evt, metric, data, log, app	Count	Uplink messages dropped because the class is disabled by policy. Helps diagnose missing traffic caused by configuration.
relay_dropped_rate	state, cfg, evt, metric, data, log, app	Count	Uplink messages dropped by token-bucket rate caps. Helps tune class-level rate limits.
relay_dropped_disconnected	state, cfg, evt, metric, data, log, app	Count	Uplink messages dropped while the site link was down or after site publish failure when the class is not buffered. Helps quantify WAN outage loss.

Scalar counter metrics

Dimensions: runtime-injected component dimensions only.

Each metric uses one measure, count.

Metric	Unit	Purpose
relay_downlinked	Count	Commands relayed from site to device. Helps measure remote control traffic.
relay_loop_dropped	Count	Messages dropped by hop-tag loop protection or max-hop checks. Helps detect relay loops or miswired bridges.
relay_routed_dropped	Count	Messages dropped by class-routing, device-pinning, or non-UNS-topic checks. Helps diagnose broker ACL or topic-shape problems.
relay_malformed_dropped	Count	Payloads that could not decode as valid EdgeCommons protobuf envelopes. Helps detect non-EdgeCommons publishers on relayed filters.
relay_publish_failed	Count	Forwarding decisions whose republish failed at the transport. Helps identify broker or network publish failures.
relay_reply_relayed	Count	Replies relayed from device back to site through the correlation map. Helps confirm request/reply proxying works.
relay_reply_expired	Count	Correlation entries removed without a reply because of TTL expiry or eviction. Helps detect slow or lost device replies.
relay_reply_stray	Count	Replies that arrived without a live correlation entry and were dropped. Helps identify late replies or duplicate reply traffic.
relay_evt_buffered	Count	Events buffered while the site link was down. Helps verify disconnect buffering is active.
relay_evt_buffer_dropped	Count	Events evicted from the full disconnect buffer. Helps size the event replay buffer.
relay_evt_replayed	Count	Buffered events replayed after site reconnect. Helps confirm recovery behavior.

Gauge metrics

Dimensions: runtime-injected component dimensions only.

Metric	Measure	Unit	Purpose
relay_pending_replies	count	Count	Current in-flight request/reply correlations. Helps detect buildup in proxied commands.
site_connected	connected	None	1 when the site broker connection is up, 0 when down. Helps drive bridge reachability alarms.