How to use @opentelemetry/metrics - 5 common examples

"use strict";

const { Meter } = require("@opentelemetry/metrics");
const { PrometheusExporter } = require("@opentelemetry/exporter-prometheus");

const meter = new Meter();

const exporter = new PrometheusExporter(
  {
    startServer: true
  },
  () => {
    console.log("prometheus scrape endpoint: http://localhost:9464/metrics");
  }
);

meter.addExporter(exporter);

// Monotonic counters and gauges can only be increased.
const monotonicCounter = meter.createCounter("monotonic_counter", {
  monotonic: true,
  labelKeys: ["pid"],

private _newMetric(
    readableMetric: ReadableMetric,
    name: string
  ): Metric | undefined {
    const metricObject = {
      name,
      // prom-client throws with empty description which is our default
      help: readableMetric.descriptor.description || 'description missing',
      labelNames: readableMetric.descriptor.labelKeys,
      // list of registries to register the newly created metric
      registers: [this._registry],
    };

    switch (readableMetric.descriptor.type) {
      case MetricDescriptorType.COUNTER_DOUBLE:
      case MetricDescriptorType.COUNTER_INT64:
        // there is no such thing as a non-monotonic counter in prometheus
        return readableMetric.descriptor.monotonic
          ? new Counter(metricObject)
          : new Gauge(metricObject);
      case MetricDescriptorType.GAUGE_DOUBLE:
      case MetricDescriptorType.GAUGE_INT64:
        return new Gauge(metricObject);
      default:
        // Other metric types are currently unimplemented
        return undefined;
    }
  }

private _newMetric(
    readableMetric: ReadableMetric,
    name: string
  ): Metric | undefined {
    const metricObject = {
      name,
      // prom-client throws with empty description which is our default
      help: readableMetric.descriptor.description || 'description missing',
      labelNames: readableMetric.descriptor.labelKeys,
      // list of registries to register the newly created metric
      registers: [this._registry],
    };

    switch (readableMetric.descriptor.type) {
      case MetricDescriptorType.COUNTER_DOUBLE:
      case MetricDescriptorType.COUNTER_INT64:
        // there is no such thing as a non-monotonic counter in prometheus
        return readableMetric.descriptor.monotonic
          ? new Counter(metricObject)
          : new Gauge(metricObject);
      case MetricDescriptorType.GAUGE_DOUBLE:
      case MetricDescriptorType.GAUGE_INT64:
        return new Gauge(metricObject);
      default:
        // Other metric types are currently unimplemented
        return undefined;
    }
  }

name,
      // prom-client throws with empty description which is our default
      help: readableMetric.descriptor.description || 'description missing',
      labelNames: readableMetric.descriptor.labelKeys,
      // list of registries to register the newly created metric
      registers: [this._registry],
    };

    switch (readableMetric.descriptor.type) {
      case MetricDescriptorType.COUNTER_DOUBLE:
      case MetricDescriptorType.COUNTER_INT64:
        // there is no such thing as a non-monotonic counter in prometheus
        return readableMetric.descriptor.monotonic
          ? new Counter(metricObject)
          : new Gauge(metricObject);
      case MetricDescriptorType.GAUGE_DOUBLE:
      case MetricDescriptorType.GAUGE_INT64:
        return new Gauge(metricObject);
      default:
        // Other metric types are currently unimplemented
        return undefined;
    }
  }

// prom-client throws with empty description which is our default
      help: readableMetric.descriptor.description || 'description missing',
      labelNames: readableMetric.descriptor.labelKeys,
      // list of registries to register the newly created metric
      registers: [this._registry],
    };

    switch (readableMetric.descriptor.type) {
      case MetricDescriptorType.COUNTER_DOUBLE:
      case MetricDescriptorType.COUNTER_INT64:
        // there is no such thing as a non-monotonic counter in prometheus
        return readableMetric.descriptor.monotonic
          ? new Counter(metricObject)
          : new Gauge(metricObject);
      case MetricDescriptorType.GAUGE_DOUBLE:
      case MetricDescriptorType.GAUGE_INT64:
        return new Gauge(metricObject);
      default:
        // Other metric types are currently unimplemented
        return undefined;
    }
  }