How to use the @opentelemetry/api-logs package?

[abhemanyus]

I am trying to use opentelemetry to collect logs as well as traces. I've got the latter working, but not the former.
To initialize api-logs, we need to create a LoggingProvider, which implements the getLogger method.
However, I have not found any documentation or guide on how to create the loggingProvider.

tracing.ts

import process from 'process';
import { NodeSDK } from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
// import { ConsoleSpanExporter } from '@opentelemetry/sdk-trace-base';
import { Resource } from '@opentelemetry/resources';
import { SemanticResourceAttributes } from '@opentelemetry/semantic-conventions';
import { OTLPTraceExporter } from "@opentelemetry/exporter-trace-otlp-http";
import { diag, DiagConsoleLogger, DiagLogLevel } from "@opentelemetry/api";
import {logs} from "@opentelemetry/api-logs";
import { ARU_INSTANCE } from "./constants";

const resource = new Resource({
    [SemanticResourceAttributes.SERVICE_NAME]: ARU_INSTANCE
  })
diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.INFO);
logs.setGlobalLoggerProvider(new DiagConsoleLogger());

// configure the SDK to export telemetry data to the console
// enable all auto-instrumentations from the meta package
// const traceExporter = new ConsoleSpanExporter();
const traceExporter = new OTLPTraceExporter({
  url: "http://172.17.0.1:4318/v1/traces"
});
const sdk = new NodeSDK({
  resource: resource,
  traceExporter,
  instrumentations: [getNodeAutoInstrumentations()]
});


// initialize the SDK and register with the OpenTelemetry API
// this enables the API to record telemetry
sdk.start();

// gracefully shut down the SDK on process exit
process.on('SIGTERM', () => {
  sdk.shutdown()
    .then(() => console.log('Tracing terminated'))
    .catch((error) => console.log('Error terminating tracing', error))
    .finally(() => process.exit(0));
});

[Flarna]

The logs feature is not implemented in SDK yet, only the API. So as of now it's a dummy implementation.

see e.g. #3549 regarding ongoing work for Logs SDK.

[abhemanyus]

Thanks a lot! You've saved me a lot of time chasing phantoms.
That said, is there a way to get logging in opentelemetry?

[Flarna]

As written above it's ongoing work. The above linked PR focuses on SDK and likely further PRs will follow to export logs to backends.

As far as I understood the log integration in OTel the API is not intended for end users to send individual log messages. It targets log frameworks like pino, windston,... So applications write log lines using one of these frameworks (like now) and the framework forwards/exports all these logs to OTel API.

This shows that there are also tasks for the log frameworks to use OtelAPI or someone to write a transport/exporter for this frameworks to close this gap.

[abhemanyus]

I see, that explains a lot. So even with a log framework like pino/winston, it is not currently possible to use them with opentelemetry.

[Flarna]

It depends what you expect from use with opentelemetry.

One aspect is enrichment of log data with trace information (add traceId/spanId in log lines). There are instrumentations like @opentelemetry/instrumentation-winston which do this.

Another aspect is to use opentelemetry as a channel to export log data to a backend. This is work in progress.

Both aspects are mostly independent and it depends on your setup/use case if you want the one or the other or both.

[abhemanyus]

Thanks for clearing that up. Guess I'll just use a logging framework with a log aggregator for now.