Metrics

Collect application and RPC metrics using OpenTelemetry's Meter API through the @connectum/otel package.

Using getMeter()

getMeter() returns a lazy singleton OpenTelemetry meter:

import { getMeter } from '@connectum/otel';

const meter = getMeter();

Counter

Track cumulative values that only increase:

const requestCounter = meter.createCounter('http.requests.total', {
  description: 'Total number of requests',
  unit: '1',
});
requestCounter.add(1, { method: 'GET', status: 200 });

Histogram

Record distributions of values (e.g., latencies):

const latencyHistogram = meter.createHistogram('request.duration', {
  description: 'Request duration in milliseconds',
  unit: 'ms',
});
latencyHistogram.record(125.5, { method: 'GET' });

UpDownCounter

Track values that can increase and decrease (e.g., active connections):

const activeConnections = meter.createUpDownCounter('connections.active');
activeConnections.add(1);   // Connection opened
activeConnections.add(-1);  // Connection closed

ObservableGauge

Report values on demand (pulled during export):

meter.createObservableGauge('memory.heap_used', {
  description: 'Heap memory usage',
  unit: 'bytes',
}).addCallback((result) => {
  result.observe(process.memoryUsage().heapUsed);
});

RPC Metrics (Automatic)

The OTel interceptors automatically record standard RPC metrics.

Server metrics (via createOtelInterceptor):

• rpc.server.duration -- request duration histogram
• rpc.server.request.size -- request message size
• rpc.server.response.size -- response message size

Client metrics (via createOtelClientInterceptor):

• rpc.client.duration -- request duration histogram
• rpc.client.request.size -- request message size
• rpc.client.response.size -- response message size

Related

• Observability Overview -- back to overview
• Tracing -- server/client interceptors, deep tracing
• Backends & Configuration -- configure metrics exporters
• @connectum/otel -- Package Guide
• @connectum/otel API -- Full API Reference