SamplingContext.request always undefined in Sentry 8

[trevorr]

It seems like SamplingContext.request always undefined for tracesSampler in Sentry 8. Here's the type definition:

/**
 * Object representing the incoming request to a node server. Passed by default when using the TracingHandler.
 */
request?: ExtractedNodeRequestData;

My understanding is that TracingHandler was removed in Sentry 8, and incoming trace requests are automatically instrumented. Should this be removed?

Here's a sample SamplingContext I'm seeing:

{
  name: 'GET /.well-known/apollo/server-health',
  attributes: {
    url: 'http://localhost:4000/.well-known/apollo/server-health',
    'http.url': 'http://localhost:4000/.well-known/apollo/server-health',
    'http.host': 'localhost:4000',
    'net.host.name': 'localhost',
    'http.method': 'GET',
    'http.scheme': 'http',
    'http.target': '/.well-known/apollo/server-health',
    'http.user_agent': 'PostmanRuntime/7.40.0',
    'http.flavor': '1.1',
    'net.transport': 'ip_tcp',
    'sentry.op': 'http.server'
  },
  transactionContext: {
    name: 'GET /.well-known/apollo/server-health',
    parentSampled: undefined
  },
  parentSampled: undefined
}

This provides a lot of the HTTP request context, but not important items like headers. How can I get access to those?

I tried adding a request hook to the HTTP instrumentation, but that appears to be called after tracesSampler.

[trevorr]

I just found this in the V8 docs, confirming that it should probably be deprecated:

sentry-javascript/docs/v8-new-performance-apis.md

Lines 246 to 249 in 5c08d03

	Currently, `tracesSampler()` can receive an arbitrary `SamplingContext` passed as argument. While this is not defined
	anywhere in detail, the shape of this context will change in v8. Going forward, this will mostly receive the attributes
	of the span, as well as some other relevant data of the span. Some properties we used to (sometimes) pass there, like
	`req` for node-based SDKs or `location` for browser tracing, will not be passed anymore.

[trevorr]

I was able to add request attributes to the root span using startIncomingSpanHook by initializing OpenTelemetry myself. However, this hook is not exposed by Sentry.httpIntegration({ instrumentation: {} }), so I don't know of a way to access the request using only Sentry. The exposed requestHook runs after the sampling decision is made.

new HttpInstrumentation({
  startIncomingSpanHook(req) {
    const attrs: SpanAttributes = {};
    const myHeader = req.headers["my_header"];
    if (myHeader) {
      attrs["my_header"] = myHeader;
    }
    return attrs;
  },
})