In this post I’ll go through a simple example on how to setup OpenTelemetry tracing in a nodejs express application.
Hello world express
// index.js
const express = require("express");
const app = express();
const port = 3000;
app.get("/", (req, res) => {
res.send("Hello World!");
});
app.listen(port, () => {
console.log(`Example app listening on port ${port}`);
});
Needed packages
First we need to add the OpenTelemetry api and sdk package
yarn add @opentelemetry/api @opentelemetry/sdk-node
To instrument express, incoming and outgoing http requests we use the express and http instrumentation libraries.
yarn add @opentelemetry/instrumentation-http @opentelemetry/instrumentation-express
And lastly we add the otlp grpc tracing exporter.
yarn add @opentelemetry/exporter-trace-otlp-grpc
Setup tracing
// tracing.js
const OpenTelemetry = require("@opentelemetry/sdk-node");
const Resources = require("@opentelemetry/resources");
const SemanticConventions = require("@opentelemetry/semantic-conventions");
const InstrumentationHttp = require("@opentelemetry/instrumentation-http");
const InstrumentationExpress = require("@opentelemetry/instrumentation-express");
const ExporterTraceOtlpGrpc = require("@opentelemetry/exporter-trace-otlp-grpc");
const sdk = new OpenTelemetry.NodeSDK({
resource: new Resources.Resource({
[SemanticConventions.SemanticResourceAttributes.SERVICE_NAME]: "my-service",
}),
traceExporter: new ExporterTraceOtlpGrpc.OTLPTraceExporter({
// url is optional and can be omitted - default is localhost:4317
url: process.env["OTEL_EXPORTER_OTLP_ENDPOINT"] || undefined,
}),
instrumentations: [
new InstrumentationHttp.HttpInstrumentation(),
new InstrumentationExpress.ExpressInstrumentation(),
],
});
sdk.start();
Run the express server
To configure and start the tracing sdk we can use nodes -r/--require
flag to preload our tracing module.
node -r ./tracing.js index.js
Now every request will be traced and exported to the configured otlp receiver.
Top comments (0)