Use Prometheus metrics exporter with the new instrumentation.ts / open telemetry

[cbarratt]

Has anyone managed to successfully use Prometheus metrics exporter as part of otel? I've managed to get it to boot, but it tries to boot multiple times, and it doesn't seem to attach to any of the metrics of the actual next routes either.

An e.g of how this was attempted implementation wise:

import { NodeSDK } from "@opentelemetry/sdk-node"
import { OTLPTraceExporter } from "@opentelemetry/exporter-trace-otlp-grpc"
import { Resource } from "@opentelemetry/resources"
import { SemanticResourceAttributes } from "@opentelemetry/semantic-conventions"
import { BatchSpanProcessor } from "@opentelemetry/sdk-trace-node"
import { diag, DiagConsoleLogger, DiagLogLevel } from "@opentelemetry/api"
import opentelemetry from "@opentelemetry/api"
import { B3InjectEncoding, B3Propagator } from "@opentelemetry/propagator-b3"
import { HttpInstrumentation } from "@opentelemetry/instrumentation-http"
import { PrometheusExporter } from "@opentelemetry/exporter-prometheus"
import { MeterProvider } from "@opentelemetry/sdk-metrics"
import { getNodeAutoInstrumentations } from "@opentelemetry/auto-instrumentations-node"

const OTLPGrpcUrl = "..."

// For troubleshooting, set the log level to DiagLogLevel.DEBUG
diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.INFO)

const applicationResource = new Resource({
  [SemanticResourceAttributes.SERVICE_NAME]: "...TEST"
})

const exporter = new PrometheusExporter({ port: 9090 })
const meterProvider = new MeterProvider({ resource: applicationResource })
meterProvider.addMetricReader(exporter)

const sdk = new NodeSDK({
  resource: applicationResource,
  spanProcessor: new BatchSpanProcessor(new OTLPTraceExporter({ url: OTLPGrpcUrl })),
  textMapPropagator: new B3Propagator({ injectEncoding: B3InjectEncoding.MULTI_HEADER }),
  instrumentations: [new HttpInstrumentation()],
})

opentelemetry.metrics.setGlobalMeterProvider(meterProvider)

sdk.start()

[danoc]

Here's a similar discussion with more comments: #16205

[Netail]

Yes; #16205 (comment)