Custom Instrumentation
On this page, you will learn how to manually propagate trace information into and out of your Node.js application.
Distributed tracing will be set up automatically if:
- You've Set Up Performance in Sentry.
- You're using one of the platforms that include distributed tracing out of the box:
@sentry/nextjs
@sentry/sveltekit
@sentry/remix
@sentry/astro
If you're not using any of the packages above, take a look at the framework-specific Sentry integrations (like our Express integration). These integrations will also enable distributed tracing automatically for your application. If you can't find an integration for your framework, it is possible to set up distributed tracing for your application manually.
If you set a tracesSampleRate
(or enableTrace
, or a tracesSampler
function), distributed tracing will be enabled out of the box.
If you want to use distributed tracing, but not performance monitoring, set the tracesSampleRate
option to 0
. The default httpIntegration
and nativeNodeFetchintegration
will automatically instrument http
and fetch
requests.
Sentry.init({
dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
integrations: [],
// Set this to 0 to enable distributed tracing without performance monitoring
tracesSampleRate: 1,
});
You can also manually extract and inject tracing data into your application. For this, you must:
- Extract and store incoming tracing information from incoming request headers or similar.
- Inject tracing information to any outgoing requests.
To learn more about distributed tracing, see our Distributed Tracing docs.
You must extract and store incoming tracing information in memory for later use. Sentry provides the continueTrace()
function to help you with this. Incoming tracing information can come from different places:
- In a web environment, it's sent with HTTP headers, for example, by another Sentry SDK used in your frontend project.
- In a job queue, it can be retrieved from meta or header variables.
- You also can pick up tracing information from environment variables.
Here's an example of how to extract and store incoming tracing information using continueTrace()
:
const http = require("http");
http.createServer((request, response) => {
const sentryTraceHeaders = request.headers["sentry-trace"];
const sentryTrace = Array.isArray(sentryTraceHeaders)
? sentryTraceHeaders.join(",")
: sentryTraceHeaders;
const baggage = request.headers["baggage"];
Sentry.continueTrace(
{ sentryTrace, baggage },
(transactionContext) => {
Sentry.startSpan({
...transactionContext,
name: "my request",
op: "http.server",
}, () => {
// Your API code...
});
}
);
});
In this example, we create a new transaction that is attached to the trace specified in the sentry-trace
and baggage
headers.
For distributed tracing to work, the two headers that you extracted and stored in the requestTransaction
, sentry-trace
and baggage
, must be added to outgoing http/fetch requests.
Here's an example of how to collect and inject this tracing information to outgoing requests:
// Create `sentry-trace` header
const sentryTraceHeader = requestTransaction.toTraceparent();
// Create `baggage` header
const dynamicSamplingContext = requestTransaction.getDynamicSamplingContext();
const sentryBaggageHeader = dynamicSamplingContextToSentryBaggageHeader(
dynamicSamplingContext
);
// Make outgoing request
fetch("https://example.com", {
method: "GET",
headers: {
baggage: sentryBaggageHeader,
"sentry-trace": sentryTraceHeader,
},
}).then((response) => {
// ...
});
In this example, tracing information is propagated to the project running at https://example.com
. If this project uses a Sentry SDK, it will extract and save the tracing information for later use.
The two services are now connected with your custom distributed tracing implementation.
If you make outgoing requests from your project to other services, check if the headers sentry-trace
and baggage
are present in the request. If so, distributed tracing is working.
Our documentation is open source and available on GitHub. Your contributions are welcome, whether fixing a typo (drat!) or suggesting an update ("yeah, this would be better").