XRay Tracing

LocalStack Pro allows to instrument your applications using XRay tracing. This helps in optimizing the interactions between service calls, and facilitates debugging of performance bottlenecks.

For example, a Python Lambda function can be instrumented as follows (based on the example here):

import boto3
from aws_xray_sdk.core import xray_recorder
from aws_xray_sdk.core import patch
patch(['boto3'])
s3_client = boto3.client('s3')

def lambda_handler(event, context):
    s3_client.create_bucket(Bucket='mybucket')
    xray_recorder.begin_subsegment('my_code')
    # your function code goes here...
    xray_recorder.end_subsegment()

Running this code in Lambda on LocalStack will result in two trace segments being created in XRay - one from the instrumented boto3 client when running create_bucket(..), and one for the custom subsegment denoted 'my_code'. You can use the regular XRay API calls (e.g., GetTraceSummaries, BatchGetTraces) to retrieve the details (timestamps, IDs, etc) of these segments.