Express OpenTelemetry Instrumentation

This document contains instructions on how to set up OpenTelemetry instrumentation in your express applications and view your application traces in SigNoz.

Requirements

Supported Versions

^4.0.0

Send traces to SigNoz Cloud

Based on your application environment, you can choose the setup below to send traces to SigNoz Cloud.

From VMs, there are two ways to send data to SigNoz Cloud.

Send traces directly to SigNoz Cloud
- No Code Automatic Instrumentation (recommended)
- Code Level Automatic Instrumentation
Send traces via OTel Collector binary (recommended)
- No Code Automatic Instrumentation (recommended)
- Code Level Automatic Instrumentation

Send traces directly to SigNoz Cloud - No Code Automatic Instrumentation (recommended)

Step 1. Install OpenTelemetry packages

npm install --save @opentelemetry/api
npm install --save @opentelemetry/auto-instrumentations-node

Step 2. Run the application

export OTEL_TRACES_EXPORTER="otlp"
export OTEL_EXPORTER_OTLP_ENDPOINT="ingest.<region>.signoz.cloud:443"
export OTEL_NODE_RESOURCE_DETECTORS="env,host,os"
export OTEL_SERVICE_NAME="<APP_NAME>"
export OTEL_EXPORTER_OTLP_HEADERS="signoz-ingestion-key=<your-ingestion-key>"
export NODE_OPTIONS="--require @opentelemetry/auto-instrumentations-node/register"
<your_run_command>

Set the <region> to match your SigNoz Cloud region
Replace <your-ingestion-key> with your SigNoz ingestion key.
<service_name> is name of your service
replace <your_run_command> with the run command of your application

Send traces directly to SigNoz Cloud - Code Level Automatic Instrumentation

Step 1. Install OpenTelemetry packages

npm install --save @opentelemetry/api@^1.6.0                                                                       
npm install --save @opentelemetry/sdk-node@^0.45.0
npm install --save @opentelemetry/auto-instrumentations-node@^0.39.4
npm install --save @opentelemetry/exporter-trace-otlp-http@^0.45.0

Step 2. Create tracing.js file
You need to configure the endpoint for SigNoz cloud in this file. You can find your ingestion key from SigNoz cloud account details sent on your email.

// 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');

// do not set headers in exporterOptions, the OTel spec recommends setting headers through ENV variables
// https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#specifying-headers-via-environment-variables

// highlight-start
const exporterOptions = {
  url: 'https://ingest.<region>.signoz.cloud:443/v1/traces'
}
// highlight-end

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

// 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));
});

Set the <region> to match your SigNoz Cloud region
<service_name> is name of your service

Step 3. Run the application
Make sure you set the OTEL_EXPORTER_OTLP_HEADERS env as follows

OTEL_EXPORTER_OTLP_HEADERS="signoz-ingestion-key=<your-ingestion-key>" node -r ./tracing.js app.js

Replace <your-ingestion-key> with your SigNoz ingestion key.

Step 4. You can validate if your application is sending traces to SigNoz cloud here.

In case you encounter an issue where all applications do not get listed in the services section then please refer to the troubleshooting section.

Send traces via OTel Collector binary - No Code Automatic Instrumentation

OTel Collector binary helps to collect logs, hostmetrics, resource and infra attributes. It is recommended to install Otel Collector binary to collect and send traces to SigNoz cloud. You can correlate signals and have rich contextual data through this way.

📝 Note

You can find instructions to install OTel Collector binary here in your VM. Once you are done setting up your OTel Collector binary, you can follow the below steps for instrumenting your Javascript application.

Send traces directly to SigNoz Cloud - No Code Automatic Instrumentation (recommended)

Step 1. Install OpenTelemetry packages

npm install --save @opentelemetry/api
npm install --save @opentelemetry/auto-instrumentations-node

Step 2. Run the application

export OTEL_TRACES_EXPORTER="otlp"
export OTEL_EXPORTER_OTLP_ENDPOINT="http://localhost:4318/v1/traces"
export OTEL_NODE_RESOURCE_DETECTORS="env,host,os"
export OTEL_SERVICE_NAME="<APP_NAME>"
export NODE_OPTIONS="--require @opentelemetry/auto-instrumentations-node/register"
<your_run_command>

Variable	Description
APP_NAME *	Name you want to give to your rust application

replace <your_run_command> with the run command of your application

Send traces via OTel Collector binary - Code Level Automatic Instrumentation

📝 Note

Step 1. Install OpenTelemetry packages

npm install --save @opentelemetry/api@^1.6.0
npm install --save @opentelemetry/sdk-node@^0.45.0
npm install --save @opentelemetry/auto-instrumentations-node@^0.39.4
npm install --save @opentelemetry/exporter-trace-otlp-http@^0.45.0

Step 2. Create tracing.js file

// 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: process.env.OTEL_EXPORTER_OTLP_ENDPOINT || 'http://localhost:4318/v1/traces',
}

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

// 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));
});

Step 3. Run the application

node -r ./tracing.js app.js

Step 4. You can validate if your application is sending traces to SigNoz cloud here.

In case you encounter an issue where all applications do not get listed in the services section then please refer to the troubleshooting section.

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:

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.
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.
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.

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

Using a specific auto-instrumentation library

If you want to instrument only your Express framework, then you need to use the following package:

npm install --save @opentelemetry/instrumentation-express

📝 Note

In the above case, you will have to install packages for all the components that you want to instrument with OpenTelemetry individually. You can find detailed instructions here.

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

📝 Note

Refer here for sample NodeJs express application with 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 redis@^2.6.0 and redis@^3.0.0 For version redis@^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()

Sample Express App

We have included a sample applications at:
Sample NodeJs App Github Repo