Trace Azure Functions written in Node.js

The @dynatrace/opentelemetry-azure-functions module provides APIs for tracing Node.js on Azure Functions.

Prerequisites

Ensure that you have followed the initial configuration steps described in Set up OpenTelemetry monitoring for Azure Functions on Consumption Plan before using the packages below.

@dynatrace/opentelemetry-azure-functions version 1.243+

Installation

To set up OpenTelemetry Node.js integration on Azure Functions, run the following command.

1npm install --save @dynatrace/opentelemetry-azure-functions

Trace export

To export traces to Dynatrace

Select one of the two ways below to initialize tracing.
- NodeTracerProvider—more lightweight than NodeSDK
- NodeSDK—typically used if you're interested in additional OpenTelemetry signals such as metrics
It is possible to bundle several Azure Functions into a single Azure Function app. It's therefore important to initialize tracing only once per Azure Function app instead of once per function. The simplest way to do this is to put a tracing setup code into a shared file as described in the Azure Functions JavaScript developer guide and require it at the top of all functions.

The tracing setup code should be implemented to set up tracing only once before any other third-party module is required.

1import { Resource } from "@opentelemetry/resources";
2import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node";
3import { SemanticResourceAttributes } from "@opentelemetry/semantic-conventions";
4import { DtSpanExporter, DtSpanProcessor, DtTextMapPropagator, DtSampler } from "@dynatrace/opentelemetry-core";
5
6const provider = new NodeTracerProvider({
7  resource: new Resource({
8    [SemanticResourceAttributes.SERVICE_NAME]: "My Service",
9  }),
10  sampler: new DtSampler(),
11  // ...other configurations
12});
13
14const exporter = new DtSpanExporter();
15const processor = new DtSpanProcessor(exporter);
16provider.addSpanProcessor(processor);
17provider.register({
18  propagator: new DtTextMapPropagator(),
19  // ...other configurations
20});

1import { Resource } from "@opentelemetry/resources";
2import { SemanticResourceAttributes } from "@opentelemetry/semantic-conventions";
3import { NodeSDK } from "@opentelemetry/sdk-node";
4import { DtSpanExporter, DtSpanProcessor, DtTextMapPropagator, DtSampler } from "@dynatrace/opentelemetry-azure-functions";
5
6const sdk = new NodeSDK({
7  resource: new Resource({
8   [SemanticResourceAttributes.SERVICE_NAME]: "My Service"
9  }),
10  sampler: new DtSampler(),
11  spanProcessor: new DtSpanProcessor(new DtSpanExporter()),
12  textMapPropagator: new DtTextMapPropagator(),
13  // ...other configurations
14});
15
16sdk.start().then(() => {
17  // Resources have been detected and SDK is started
18});

Wrap your function handler as below and export the wrapped handler.

1import type { AzureFunction, Context, HttpRequest } from "@azure/functions"
2// Import the wrapHandler function.
3import { wrapHandler } from "@dynatrace/opentelemetry-azure-functions";
4
5const httpTrigger: AzureFunction = async function (context: Context, req: HttpRequest): Promise<void> {
6  // The created span is set as active by the OpenTelemetry ContextManager here
7  context.log("HTTP trigger function processed a request.");
8
9  const name = (req.query.name || (req.body && req.body.name));
10  const responseMessage = name
11    ? "Hello, " + name + ". This HTTP triggered function executed successfully."
12    : "This HTTP triggered function executed successfully. Pass a name in the query string or in the request body for a personalized response.";
13
14  context.res = {
15    status: 200,
16    body: responseMessage
17  };
18};
19
20// Export the wrapped handler function.
21export default wrapHandler(httpTrigger);

Compatibility

OneAgent version	OpenTelemetry API	OpenTelemetry SDK
1.243 - 1.255	1.x.y	1.0.x
1.257	1.x.y	1.0.x - 1.7.x
1.259+	1.x.y	1.0.x - 1.8.x
1.261+	1.x.y	1.0.x - 1.9.x
1.265+	1.x.y	1.0.x - 1.10.x
1.273+	1.x.y	1.0.x - 1.15.x

Supported Azure Functions runtime:

Limitations

Only async function handlers are supported.
- This follows the Azure recommendation to use async and await.
- wrapHandler returns any non-async function unwrapped, so the function itself will work but no span will be created.
- Note that async functions were introduced in ECMAScript 2017. No span will be created if an earlier version of ECMAScript is used. In case TypeScript is used, make sure compilation target is set to ECMAScript 2017 or higher.
Signaling function completion using the deprecated context.done() or context.res.send() calls is not supported. Either use a $return binding and return the result from the function handler, or use a named out binding and set context.binding.<name>. For HTTP triggers, setting context.res is also supported.