What is `Active tracing` mean in lambda with Xray?

user_5421539 0
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I deployed a lambda with xray is enabled. And I am able to see all trace in XRay console from my lambda. But I can see a warning message in below screenshot. It shows Active tracing requires permissions that are not configured to lambda. But I don't understand what Active tracing mean. I have read article like this https://docs.aws.amazon.com/xray/latest/devguide/xray-services-lambda.html but it doesn't explain very well.

So what does Active tracing mean and does it cost too much?

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aws-lambda amazon-web-services
2 Answers

I also had this warning under "Active tracing." If you click into Edit it gives a bit more explanation, saying it needs permission to send trace data.

You can find the documentation here, but the short version is that you'll want to add the AWSXRayDaemonWriteAccess policy to your lambda function's execution role.

user_68802720

The different levels of x-ray integration with AWS services is explained here:

  • Active instrumentation – Samples and instruments incoming requests.
  • Passive instrumentation – Instruments requests that have been sampled by another service.
  • Request tracing – Adds a tracing header to all incoming requests and propagates it downstream.
  • Tooling – Runs the X-Ray daemon to receive segments from the X-Ray SDK.

AWS Lambda supports both active and passive instrumentation. So basically you use passive instrumentation if your function handles requests that have been sampled by some other service (e.g. API gateway). In contrast, if your function gets "raw" un-sampled requests, you should use active instrumentation, so that the sampling takes place.

user_2488230
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