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Javascript OpenTelemetry Instrumentation

This document contains OpenTelemetry instrumentation instructions for Javascript backend frameworks and modules based on Nodejs.

Traces​

Requirements

You can use OpenTelemetry Nodejs client libraries to send your traces directly to SigNoz. You have two choices for instrumenting your Nodejs application with OpenTelemetry.

info

If you are on K8s, you should checkout opentelemetry operators which enable auto instrumenting Javascript applications very easily.

  • Use a specific auto-instrumentation library
    You can use individual auto-instrumentation libraries too for a specific component of your application. For example, you can use @opentelemetry/instrumentation-express for instrumenting the Express web framework.

Using the all-in-one auto-instrumentation library​

The recommended way to instrument your Javascript Nodejs application is to use the all-in-one auto-instrumentation library - @opentelemetry/auto-instrumentations-node. It provides a simple way to initialize multiple Nodejs instrumentations.

Internally, it calls the specific auto-instrumentation library for components used in the application. You can see the complete list here.

The instrumentation automatically identifies the following within your application:

  • Frameworks, such as Express, Nestjs
  • Common protocols such as HTTP, HTTPS, and gRPC
  • Databases, such as MySQL, MongoDB, Redis, etc.
  • Other libraries used in the application
All in one OpenTelemetry nodejs instrumentation
All in one auto instrumentation library - identifies and instruments packages used by your Nodejs application

Steps to auto-instrument Nodejs application​

  1. Install the dependencies
    We start by installing the relevant dependencies.

    npm install --save @opentelemetry/sdk-node
    npm install --save @opentelemetry/auto-instrumentations-node
    npm install --save @opentelemetry/exporter-trace-otlp-http

    The dependencies included are briefly explained below:

    @opentelemetry/sdk-node - This package provides the full OpenTelemetry SDK for Node.js including tracing and metrics.

    @opentelemetry/auto-instrumentations-node - This module provides a simple way to initialize multiple Node instrumentations.

    @opentelemetry/exporter-trace-otlp-http - This module provides the exporter to be used with OTLP (http/json) compatible receivers.

  2. Create a tracing.js file
    The tracing.js file will contain the tracing setup code. Notice, that we have set some environment variables in the code(highlighted). You can update these variables based on your environment.

      // tracing.js
    'use strict'
    const process = require('process');
    const opentelemetry = require('@opentelemetry/sdk-node');
    const { getNodeAutoInstrumentations } = require('@opentelemetry/auto-instrumentations-node');
    const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-http');
    const { Resource } = require('@opentelemetry/resources');
    const { SemanticResourceAttributes } = require('@opentelemetry/semantic-conventions');

    const exporterOptions = {
    url: 'http://localhost:4318/v1/traces'
    }

    const traceExporter = new OTLPTraceExporter(exporterOptions);
    const sdk = new opentelemetry.NodeSDK({
    traceExporter,
    instrumentations: [getNodeAutoInstrumentations()],
    resource: new Resource({
    [SemanticResourceAttributes.SERVICE_NAME]: 'node_app'
    })
    });

    // initialize the SDK and register with the OpenTelemetry API
    // this enables the API to record telemetry
    sdk.start()
    .then(() => console.log('Tracing initialized'))
    .catch((error) => console.log('Error initializing tracing', error));

    // 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));
    });

    OpenTelemetry Node SDK currently does not detect the OTEL_RESOURCE_ATTRIBUTES from .env files as of today. That’s why we need to include the variables in the tracing.js file itself.

    About environment variables:

    service_name : node_app (you can give whatever name that suits you)

    http://localhost:4318/v1/traces is the default url for sending your tracing data. We are assuming you have installed SigNoz on your localhost. Based on your environment, you can update it accordingly. It should be in the following format:

    http://<IP of SigNoz backend>:4318/v1/traces

    note

    Remember to allow incoming requests to port 4318 of machine where SigNoz backend is hosted.

  1. Run the application
    The tracing configuration should be run before your application code. We will use the -r, —require module flag for that.

      node -r ./tracing.js app.js

    If you don't want to use the -require flag, you can also import tracing.js in your main application. The import ./tracing.js should be the first line of your application code and initialize it before any other function. Here's the sample GitHub repo which shows the implementation.

Validating instrumentation by checking for traces​

With your application running, you can verify that you’ve instrumented your application with OpenTelemetry correctly by confirming that tracing data is being reported to SigNoz.

To do this, you need to ensure that your application generates some data. Applications will not produce traces unless they are being interacted with, and OpenTelemetry will often buffer data before sending. So you need to interact with your application and wait for some time to see your tracing data in SigNoz.

Validate your traces in SigNoz:

  1. Trigger an action in your app that generates a web request. Hit the endpoint a number of times to generate some data. Then, wait for some time.
  2. In SigNoz, open the Services tab. Hit the Refresh button on the top right corner, and your application should appear in the list of Applications.
  3. Go to the Traces tab, and apply relevant filters to see your application’s traces.

You might see other dummy applications if you’re using SigNoz for the first time. You can remove it by following the docs here.

Node Application in the list of services being monitored in SigNoz
Node Application in the list of services being monitored in SigNoz

If you don't see your application reported in the list of services, try our troubleshooting guide.

Using a specific auto-instrumentation library​

If total installation size is not constrained, it is recommended to use the @opentelemetry/auto-instrumentations-node bundle with @opentelemetry/sdk-node for the most seamless instrumentation experience.

But you can also install specific auto-instrumenation packages for the components used by your application.

All in one OpenTelemetry nodejs instrumentation
You can also choose individual auto-instrumenation libraries, but the all-in-one library is recommended to get started

If an application uses Express, HTTP, and MongoDB, we can instrument the application using the following modules:

  • opentelemetry-instrumentation-express
  • opentelemetry/instrumentation-mongodb
  • opentelemetry/instrumentation-http

If you are using Express, the instrumentation relies on HTTP calls to also be instrumented. That’s why we’re also including the module for http instrumentation. Let’s see the steps required.

Steps to use specific auto-instrumentation libraries

  1. Install the dependencies
    We start by installing the relevant dependencies.

    npm install --save @opentelemetry/sdk-node
    npm install --save @opentelemetry/exporter-trace-otlp-http
    npm install --save @opentelemetry/instrumentation-express
    npm install --save @opentelemetry/instrumentation-mongodb
    npm install --save @opentelemetry/instrumentation-http
  2. Creat a tracing.js file
    The tracing.js file will contain the following tracing setup code.

    // tracing.js
    'use strict'
    const process = require('process');
    //OpenTelemetry
    const opentelemetry = require('@opentelemetry/sdk-node');
    const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-http');
    //instrumentations
    const { ExpressInstrumentation } = require("@opentelemetry/instrumentation-express");
    const { MongoDBInstrumentation } = require("@opentelemetry/instrumentation-mongodb");
    const { HttpInstrumentation } = require("@opentelemetry/instrumentation-http");

    const { Resource } = require('@opentelemetry/resources');
    const { SemanticResourceAttributes } = require('@opentelemetry/semantic-conventions');

    const exporterOptions = {
    url: 'http://localhost:4318/v1/traces'
    }

    const traceExporter = new OTLPTraceExporter(exporterOptions);
    const sdk = new opentelemetry.NodeSDK({
    traceExporter,
    instrumentations: [new ExpressInstrumentation(), new MongoDBInstrumentation(), new HttpInstrumentation()],
    resource: new Resource({
    [SemanticResourceAttributes.SERVICE_NAME]: 'node_app'
    })
    });

    // initialize the SDK and register with the OpenTelemetry API
    // this enables the API to record telemetry
    sdk.start()
    .then(() => console.log('Tracing initialized'))
    .catch((error) => console.log('Error initializing tracing', error));

    // 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));
    });

    OpenTelemetry Node SDK currently does not detect the OTEL_RESOURCE_ATTRIBUTES from .env files as of today. That’s why we need to include the variables in the tracing.js file itself.

    About environment variables:

    service_name : node_app (you can give whatever name that suits you)

    http://localhost:4318/v1/traces is the default url for sending your tracing data. We are assuming you have installed SigNoz on your localhost. Based on your environment, you can update it accordingly. It should be in the following format:

    http://<IP of SigNoz backend>:4318/v1/traces

    note

    Remember to allow incoming requests to port 4318 of machine where SigNoz backend is hosted.

  3. Run the application
    The tracing configuration should be run before your application code. We will use the -r, —require module flag for that.

      node -r ./tracing.js app.js

    If you don't want to use the -require flag, you can also import tracing.js in your main application. The import ./tracing.js should be the first line of your application code and initialize it before any other function. Here's the sample GitHub repo which shows the implementation.

With your application running, you can verify that you’ve instrumented your application with OpenTelemetry correctly by validating if your traces are being to SigNoz.

Instrumentation Modules for Databases​

The @opentelemetry/auto-instrumentations-node can inititialize instrumentation for popular databases. Hence it’s recommended to get started with it.

But if you are using specific auto-instrumentation packages, here’s a list of packages for popular databases.

MongoDB instrumentation​

Note if you’re using @opentelemetry/auto-instrumentations-node, you don’t need to install specific modules for your database.

Supported Versions

• >=3.3 <5

Module that provides automatic instrumentation for MongoDB:

npm install --save @opentelemetry/instrumentation-mongodb

Redis Instrumentation​

Note if you’re using @opentelemetry/auto-instrumentations-node, you don’t need to install specific modules for your database.

Supported Versions

This package supports [email protected]^2.6.0 and [email protected]^3.0.0 For version [email protected]^4.0.0, please use @opentelemetry/instrumentation-redis-4

npm install --save @opentelemetry/instrumentation-redis

MySQL Instrumentation​

Note if you’re using @opentelemetry/auto-instrumentations-node, you don’t need to install specific modules for your database.

Supported Versions

• 2.x

Module that provides automatic instrumentation for MySQL:

npm install --save @opentelemetry/instrumentation-mysql

Memcached Instrumentation​

Note if you’re using @opentelemetry/auto-instrumentations-node, you don’t need to install specific modules for your database.

Supported Versions

  • >=2.2

Module that provides automatic instrumentation for Memcached:

npm install --save @opentelemetry/instrumentation-memcached

Troubleshooting your installation​

Set an environment variable to run the OpenTelemetry launcher in debug mode, where it logs details about the configuration and emitted spans:

export OTEL_LOG_LEVEL=debug

The output may be very verbose with some benign errors. Early in the console output, look for logs about the configuration. Next, look for lines like the ones below, which are emitted when spans are emitted to SigNoz.

{
"traceId": "985b66d592a1299f7d12ebca56ca1fe3",
"parentId": "8d62a70aa335a227",
"name": "bar",
"id": "17ada85c3d55376a",
"kind": 0,
"timestamp": 1685674607399000,
"duration": 299,
"attributes": {},
"status": { "code": 0 },
"events": []
}
{
"traceId": "985b66d592a1299f7d12ebca56ca1fe3",
"name": "foo",
"id": "8d62a70aa335a227",
"kind": 0,
"timestamp": 1585130342183948,
"duration": 315,
"attributes": {
"name": "value"
},
"status": { "code": 0 },
"events": [
{
"name": "event in foo",
"time": [1585130342, 184213041]
}
]
}

Running short applications (Lambda/Serverless/etc) If your application exits quickly after startup, you may need to explicitly shutdown the tracer to ensure that all spans are flushed:

opentelemetry.trace.getTracer('your_tracer_name').getActiveSpanProcessor().shutdown()

 

Further Reading​

Frequently Asked Questions​

  1. How to find what to use in IP of SigNoz if I have installed SigNoz in Kubernetes cluster?

    Based on where you have installed your application and where you have installed SigNoz, you need to find the right value for this. Please use this grid to find the value you should use for IP of SigNoz

  2. I am sending data from my application to SigNoz, but I don't see any events or graphs in the SigNoz dashboard. What should I do?

    This could be because of one of the following reasons:

    1. Your application is generating telemetry data, but not able to connect with SigNoz installation

      Please use this troubleshooting guide to find if your application is able to access SigNoz installation and send data to it.

    2. Your application is not actually generating telemetry data

      Please check if the application is generating telemetry data first. You can use Console Exporter to just print your telemetry data in console first. Join our Slack Community if you need help on how to export your telemetry data in console

    3. Your SigNoz installation is not running or behind a firewall

      Please double check if the pods in SigNoz installation are running fine. docker ps or kubectl get pods -n platform are your friends for this.