xrayPyExamplesLambda

AWS X-Ray is a service that helps developers debug, instrument, and performance tune applications. This example demostrates how to use the AWS [X-Ray SDK] (http://docs.aws.amazon.com/xray/latest/devguide/xray-sdk-python.html) for Python. to instrument a "mock" application.

Introduction

First, add two directives to your Python source code

from aws_xray_sdk.core import xray_recorder
from aws_xray_sdk.core import patch

Second, install the required depedency

pip install aws-xray-sdk
pip3 install aws-xray-sdk

Third, wrap sections of your code in subsegements like this:

subsegment = xray_recorder.begin_subsegment('subsegment_name')

# code here...

xray_recorder.end_subsegment()

Testing

Lambda functions can be invoked either Asynchronously or Synchronously. To invoke your Lambda function in Async mode specify the --invocation-type flag Event:

Async Test

aws lambda invoke --function-name xrayPyTest --invocation-type Event out.txt

This X-Ray Trace shows a Lambda function running in Async mode for the first time, with a Cold Start. Notice the Dwell time under AWS::Lambda and the overall duration was just under 1.8s.

This X-Ray Trace shows a Lambda function runnning when Warm. Notice the overall duration was under 250ms.

Sync Test

To invoke your function in Sync, remove the --invoication-type flag, it will default to RequestResponse

aws lambda invoke --function-name xrayPyTest  out.txt

This X-Ray trace shows a Lambda function running in Sync mode for the first time, with a Cold Start. Notice the Initialization record under AWS::Lambda::Function and overall function duration of 1.6s.

This X-Ray trace shows a Lambda function running when Warm. Notice there is no Initialization and the function runs under 160ms.

Resources

• xrayPyTest - Python example that demostrates how to instrument code with the X-Ray SDK.