Application Real-Time Monitoring Service:Use Managed Service for OpenTelemetry to submit the trace data of a Node.js application

Background information

OpenTelemetry provides multiple automatic instrumentation plug-ins that can be used to automatically create spans for common frameworks. The following table describes the supported frameworks. For more information, see OpenTelemetry documentation.

Sample code

You can download the sample code from opentelemetry-nodejs-demo.

Method 1: Automatic instrumentation (recommended)

1. Download the dependencies required to run the project.

   cd auto-instrumentation
   
   npm init -y
   npm install express
   npm install axios

2. Download the dependencies required for OpenTelemetry automatic instrumentation.

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

3. Write the application code.

   The following code provides a simple example implemented by using Express:

   "use strict";
   
   const axios = require("axios").default;
   const express = require("express");
   const app = express();
   
   app.get("/", async (req, res) => {
     const result = await axios.get("http://localhost:7001/hello");
     return res.status(201).send(result.data);
   });
   
   app.get("/hello", async (req, res) => {
     console.log("hello world!")
     res.json({ code: 200, msg: "success" });
   });
   
   app.use(express.json());
   
   app.listen(7001, () => {
     console.log("Listening on http://localhost:7001");
   });

4. Use environment variables to set OpenTelemetry parameters and run the application.

   Replace ${httpEndpoint} with the HTTP endpoint obtained in Prerequisites. Replace ${serviceName} with the application name.

   export OTEL_TRACES_EXPORTER="otlp"
   export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="${httpEndpoint}"
   export OTEL_NODE_RESOURCE_DETECTORS="env,host,os"
   export OTEL_SERVICE_NAME="${serviceName}"
   export NODE_OPTIONS="--require @opentelemetry/auto-instrumentations-node/register"
   node main.js

   Note

   For information about OpenTelemetry environment variables, see Automatic Instrumentation Configuration.

5. Access the application.

   Access the application by running the following command or using a browser. Then, you can generate traces and report the trace data to Managed Service for OpenTelemetry.

   curl localhost:7001/hello

Method 2: Manual instrumentation

1. Add the following dependencies on OpenTelemetry to the package.json file.

    "dependencies": {
       "@opentelemetry/api": "^1.0.4",
       "@opentelemetry/exporter-trace-otlp-grpc": "^0.27.0",
       "@opentelemetry/instrumentation": "^0.27.0",
       "@opentelemetry/instrumentation-express": "^0.27.0",
       "@opentelemetry/instrumentation-http": "^0.27.0",
       "@opentelemetry/resources": "^1.0.1",
       "@opentelemetry/sdk-trace-base": "^1.0.1",
       "@opentelemetry/sdk-trace-node": "^1.0.1"
     }

2. Create a provider.

   const { Resource } = require("@opentelemetry/resources");
   const { NodeTracerProvider } = require("@opentelemetry/sdk-trace-node");
   const {
     SemanticResourceAttributes,
   } = require("@opentelemetry/semantic-conventions");
   
   const provider = new NodeTracerProvider({
     resource: new Resource({
       [SemanticResourceAttributes.HOST_NAME]: require("os").hostname(),
       [SemanticResourceAttributes.SERVICE_NAME]: "opentelemetry-express",    // You can replace opentelemetry-express with the actual service name. 
     }),
   });

3. Register the HTTP and Express frameworks by using the provider. Applications in these frameworks are automatically monitored and intercepted.

   Note

   For information about how to monitor Node.js applications in other frameworks, see OpenTelemetry documentation.

   const { registerInstrumentations } = require("@opentelemetry/instrumentation");
   const { HttpInstrumentation } = require("@opentelemetry/instrumentation-http");
   const {
     ExpressInstrumentation,
   } = require("@opentelemetry/instrumentation-express");
   
   registerInstrumentations({
     tracerProvider: provider,
     instrumentations: [new HttpInstrumentation(), ExpressInstrumentation],
   });

4. Configure an exporter to export data to Managed Service for OpenTelemetry.

   Replace <ENDPOINT> and <AUTHENTICATION> in the following code with the endpoint and token that are obtained in "Prerequisites".

   const metadata = new grpc.Metadata();
   metadata.set("Authentication", "<AUTHENTICATION>");
   
   const exporter = new OTLPTraceExporter({ url: "<ENDPOINT>", metadata });
   provider.addSpanProcessor(new SimpleSpanProcessor(exporter));
   provider.register();

5. Optional. Add a custom event and attributes.

   Note

   For information about how to use the OpenTelemetry API, see OpenTelemetry documentation.

   const api = require("@opentelemetry/api");
   const currentSpan = api.trace.getSpan(api.context.active());
   currentSpan.addEvent("timestamp", { value: Date.now() });
   currentSpan.setAttribute("tagKey-01", "tagValue-01");

View trace data in the ARMS console