opentelemetry-node-metrics

A modernized set of node metrics for OpenTelemetry. Based on two excellent modules:

- Marc Bachmann's opentelemetry-node-metrics
- Simon Nyberg's prom-client

Usage:

``sh
yarn add @sesamecare-oss/opentelemetry-node-metrics
`

Wire up OTEL as normal - using node auto instrumentations or manual setup as you wish. Then, at an appropriate place, include something like the below:

`ts
import { metrics } from '@opentelemetry/api';
import { setupNodeMetrics } from '@sesamecare-oss/opentelemetry-node-metrics';

const meter = metrics.getMeterProvider().getMeter('node-metrics');
setupNodeMetrics(meter);
``

Now your Prometheus-exported metrics should be included along with whatever other metrics you have selected. See openapi-typescript-infra/service for a more complete example of metrics integrated with an express service host.

One notable change from the existing libraries - they divide active handles and active 'requests' using deprecated Node APIs. I've chosen to merge these into 'resources' using the new getActiveResourcesInfo API, which is Node17+. It should fail gracefully if that function is not available.