Send logs from Node.js default logger to SigNoz using OpenTelemetry

Prerequisites

Node.js version 18 or higher
An instance of SigNoz (either Cloud or Self-Hosted)
An existing Node.js application

Send logs to SigNoz

This guide will walk you through instrumenting your Node.js application to send logs from the default console logger to SigNoz using the OpenTelemetry (OTel) SDK.

Step 1: Install dependencies

Install the required OpenTelemetry packages:

npm install --save @opentelemetry/api-logs \
  @opentelemetry/sdk-logs \
  @opentelemetry/exporter-logs-otlp-http \
  @opentelemetry/resources \
  @opentelemetry/semantic-conventions \
  express

npm install --save @opentelemetry/api-logs \
  @opentelemetry/sdk-logs \
  @opentelemetry/exporter-logs-otlp-http \
  @opentelemetry/resources \
  @opentelemetry/semantic-conventions \
  express \
  typescript \
  ts-node \
  @types/node \
  @types/express

yarn add @opentelemetry/api-logs \
  @opentelemetry/sdk-logs \
  @opentelemetry/exporter-logs-otlp-http \
  @opentelemetry/resources \
  @opentelemetry/semantic-conventions \
  express

yarn add @opentelemetry/api-logs \
  @opentelemetry/sdk-logs \
  @opentelemetry/exporter-logs-otlp-http \
  @opentelemetry/resources \
  @opentelemetry/semantic-conventions \
  express \
  typescript \
  ts-node \
  @types/node \
  @types/express

Step 2: Set environment variables

Set the following environment variables to configure the OpenTelemetry exporter:

export OTEL_EXPORTER_OTLP_ENDPOINT="https://ingest.<region>.signoz.cloud:443"
export OTEL_EXPORTER_OTLP_HEADERS="signoz-ingestion-key=<SIGNOZ_INGESTION_KEY>"
export OTEL_SERVICE_NAME="nodejs-console-app"

Replace the following:

<region>: Your SigNoz Cloud region.
<SIGNOZ_INGESTION_KEY>: Your SigNoz ingestion key.

If using a local OTel Collector (VM), use:

export OTEL_EXPORTER_OTLP_ENDPOINT="http://localhost:4318"
# Do not set OTEL_EXPORTER_OTLP_HEADERS

Add these environment variables to your deployment manifest:

env:
  - name: OTEL_EXPORTER_OTLP_ENDPOINT
    value: 'https://ingest.<region>.signoz.cloud:443'
  - name: OTEL_EXPORTER_OTLP_HEADERS
    value: 'signoz-ingestion-key=<SIGNOZ_INGESTION_KEY>'
  - name: OTEL_SERVICE_NAME
    value: 'nodejs-console-app'

Replace the following:

<region>: Your SigNoz Cloud region.
<SIGNOZ_INGESTION_KEY>: Your SigNoz ingestion key.

⚠️ Warning

Avoiding Duplicate Logs

If using the k8s-infra chart (which auto-collects container logs), disable log collection for this application to prevent duplicates.

See how to disable log collection →

Create a Dockerfile in your project root:

FROM node:20-alpine

WORKDIR /app

# Copy package files
COPY package*.json ./

# Install dependencies
RUN npm install

# Copy instrumentation files and application code
COPY logger.js ./
COPY console-instrumentation.js ./
COPY . .

# Set OpenTelemetry environment variables
ENV OTEL_EXPORTER_OTLP_ENDPOINT="https://ingest.<region>.signoz.cloud:443"
ENV OTEL_EXPORTER_OTLP_HEADERS="signoz-ingestion-key=<SIGNOZ_INGESTION_KEY>"
ENV OTEL_SERVICE_NAME="nodejs-console-app"

# Expose application port
EXPOSE 3000

# Start the application
CMD ["node", "index.js"]

Build and run the container:

# Build the image
docker build -t nodejs-console-app .

# Run the container
docker run -p 3000:3000 nodejs-console-app

Replace the placeholders in the Dockerfile:

<region>: Your SigNoz Cloud region.
<SIGNOZ_INGESTION_KEY>: Ingestion key for your SigNoz Cloud, see Ingestion Keys.

Set environment variables in PowerShell:

$env:OTEL_EXPORTER_OTLP_ENDPOINT = "https://ingest.<region>.signoz.cloud:443"
$env:OTEL_EXPORTER_OTLP_HEADERS = "signoz-ingestion-key=<SIGNOZ_INGESTION_KEY>"
$env:OTEL_SERVICE_NAME = "nodejs-console-app"

Replace the placeholders:

<region>: Your SigNoz Cloud region.
<SIGNOZ_INGESTION_KEY>: Ingestion key for your SigNoz Cloud, see Ingestion Keys.

Step 3: Configure OpenTelemetry Logger

Create a new file called logger.js or logger.ts in your project root. This file reads the configuration from the environment variables set in the previous step.

logger.js

const {
  LoggerProvider,
  BatchLogRecordProcessor,
} = require("@opentelemetry/sdk-logs");
const { OTLPLogExporter } = require("@opentelemetry/exporter-logs-otlp-http");
const { resourceFromAttributes } = require("@opentelemetry/resources");
const { ATTR_SERVICE_NAME } = require("@opentelemetry/semantic-conventions");

// Create a resource with your service information
const resource = resourceFromAttributes({
  [ATTR_SERVICE_NAME]: process.env.OTEL_SERVICE_NAME || "nodejs-console-app",
});

// Configure the OTLP exporter
// It automatically reads OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_EXPORTER_OTLP_HEADERS
const logExporter = new OTLPLogExporter({});

// Create and configure the logger provider
const loggerProvider = new LoggerProvider({
  resource,
  processors: [new BatchLogRecordProcessor(logExporter)], // Configure batch processor
});
module.exports = loggerProvider;

logger.ts

import {
  LoggerProvider,
  BatchLogRecordProcessor,
} from "@opentelemetry/sdk-logs";
import { OTLPLogExporter } from "@opentelemetry/exporter-logs-otlp-http";
import { resourceFromAttributes } from "@opentelemetry/resources";
import { ATTR_SERVICE_NAME } from "@opentelemetry/semantic-conventions";

// Create a resource with your service information
const resource = resourceFromAttributes({
  [ATTR_SERVICE_NAME]: process.env.OTEL_SERVICE_NAME || "nodejs-console-app",
});

// Configure the OTLP exporter
// It automatically reads OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_EXPORTER_OTLP_HEADERS
const logExporter = new OTLPLogExporter({});

// Create and configure the logger provider
const loggerProvider = new LoggerProvider({
  resource,
  processors: [new BatchLogRecordProcessor(logExporter)], // Configure batch processor
});

export default loggerProvider;

Step 4: Instrument the Default Console Logger

Create a new file called console-instrumentation.js or console-instrumentation.ts in your project root. This file wraps the default console methods to send logs to OpenTelemetry:

console-instrumentation.js

require("@opentelemetry/api-logs");
const loggerProvider = require("./logger");

// Get a logger instance
const logger = loggerProvider.getLogger("default", "1.0.0");

// Store original console methods
const originalConsole = {
  log: console.log,
  info: console.info,
  warn: console.warn,
  error: console.error,
  debug: console.debug,
};

// Map severity levels
const SeverityNumber = {
  DEBUG: 5,
  INFO: 9,
  WARN: 13,
  ERROR: 17,
};

// Override console methods
console.log = function (...args) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.INFO,
    severityText: "INFO",
    body: message,
    attributes: {},
  });

  originalConsole.log.apply(console, args);
};

console.info = function (...args) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.INFO,
    severityText: "INFO",
    body: message,
    attributes: {},
  });

  originalConsole.info.apply(console, args);
};

console.warn = function (...args) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.WARN,
    severityText: "WARN",
    body: message,
    attributes: {},
  });

  originalConsole.warn.apply(console, args);
};

console.error = function (...args) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.ERROR,
    severityText: "ERROR",
    body: message,
    attributes: {},
  });

  originalConsole.error.apply(console, args);
};

console.debug = function (...args) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.DEBUG,
    severityText: "DEBUG",
    body: message,
    attributes: {},
  });

  originalConsole.debug.apply(console, args);
};

console-instrumentation.ts

import "@opentelemetry/api-logs";
import loggerProvider from "./logger";

// Get a logger instance
const logger = loggerProvider.getLogger("default", "1.0.0");

// Store original console methods
const originalConsole = {
  log: console.log,
  info: console.info,
  warn: console.warn,
  error: console.error,
  debug: console.debug,
};

// Map severity levels
const SeverityNumber = {
  DEBUG: 5,
  INFO: 9,
  WARN: 13,
  ERROR: 17,
};

// Override console methods
console.log = function (...args: any[]) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.INFO,
    severityText: "INFO",
    body: message,
    attributes: {},
  });

  originalConsole.log.apply(console, args);
};

console.info = function (...args: any[]) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.INFO,
    severityText: "INFO",
    body: message,
    attributes: {},
  });

  originalConsole.info.apply(console, args);
};

console.warn = function (...args: any[]) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.WARN,
    severityText: "WARN",
    body: message,
    attributes: {},
  });

  originalConsole.warn.apply(console, args);
};

console.error = function (...args: any[]) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.ERROR,
    severityText: "ERROR",
    body: message,
    attributes: {},
  });

  originalConsole.error.apply(console, args);
};

console.debug = function (...args: any[]) {
  const message = args
    .map((arg) => (typeof arg === "object" ? JSON.stringify(arg) : String(arg)))
    .join(" ");

  logger.emit({
    severityNumber: SeverityNumber.DEBUG,
    severityText: "DEBUG",
    body: message,
    attributes: {},
  });

  originalConsole.debug.apply(console, args);
};

Step 5: Initialize Instrumentation in Your Application

Import the instrumentation at the very top of your main application file (e.g., index.js or index.ts):

index.js

// This must be the first import
require('./console-instrumentation')

// Your application code follows
const express = require('express')
const app = express()

console.log('Application started')
console.error('This is an error message')

app.listen(3000, () => {
  console.info('Server listening on port 3000')
})

index.ts

// This must be the first import
import './console-instrumentation';

// Your application code follows
import express from 'express';
const app = express();

console.log('Application started');
console.error('This is an error message');

app.listen(3000, () => {
  console.info('Server listening on port 3000');
});

Step 6: Run Your Application

Run your application:

node index.js

Validate Logs

Captured logs can be viewed in the Logs Explorer section.

Setup OpenTelemetry Collector (Optional)

What is the OpenTelemetry Collector?

Think of the OTel Collector as a middleman between your app and SigNoz. Instead of your application sending data directly to SigNoz, it sends everything to the Collector first, which then forwards it along.

Why use it?

Cleaning up data — Filter out noisy traces you don't care about, or remove sensitive info before it leaves your servers.
Keeping your app lightweight — Let the Collector handle batching, retries, and compression instead of your application code.
Adding context automatically — The Collector can tag your data with useful info like which Kubernetes pod or cloud region it came from.
Future flexibility — Want to send data to multiple backends later? The Collector makes that easy without changing your app.

See Switch from direct export to Collector for step-by-step instructions to convert your setup.

For more details, see Why use the OpenTelemetry Collector? and the Collector configuration guide.

Troubleshooting

Why do I see "404 Not Found" errors?

This usually happens if the endpoint URL is incorrect.

Cloud: https://ingest.<region>.signoz.cloud:443
Self-Hosted: http://localhost:4318

Why are my logs not appearing in SigNoz?

Check if the application started successfully and is actually generating logs.
Verify your <region> and <SIGNOZ_INGESTION_KEY> are correct.
If using console.log, ensure console-instrumentation.js is required before any other code in your application.

Next Steps

Get Help

If you need help with the steps in this topic, please reach out to us on SigNoz Community Slack.

If you are a SigNoz Cloud user, please use in product chat support located at the bottom right corner of your SigNoz instance or contact us at cloud-support@signoz.io.

Send logs from Node.js default logger to SigNoz using OpenTelemetry

Prerequisites

Send logs to SigNoz

Step 1: Install dependencies

Step 2: Set environment variables

Step 3: Configure OpenTelemetry Logger

Step 4: Instrument the Default Console Logger

Step 5: Initialize Instrumentation in Your Application

Step 6: Run Your Application

Validate Logs

Setup OpenTelemetry Collector (Optional)

What is the OpenTelemetry Collector?

Why use it?

Troubleshooting

Why do I see "404 Not Found" errors?

Why are my logs not appearing in SigNoz?

Next Steps

Get Help

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