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Difficulty: HardInstrumenting Distributed Tracing with AWS X-Ray

An e-commerce application uses Amazon API Gateway to trigger an AWS Lambda function that processes checkout requests. Although API Gateway and Lambda have active tracing enabled, the downstream calls made by the Lambda function using the AWS SDK for Python (Boto3) to an Amazon DynamoDB table are missing from the trace map in AWS X-Ray. What should the developer do to ensure downstream DynamoDB calls are included in the trace?

  1. A
    Increase the Lambda function timeout to ensure the background X-Ray daemon has enough time to transmit the DynamoDB segment before the container stops.
  2. B
    Change the API Gateway integration type to Lambda Custom Integration and configure a mapping template to extract the trace ID header.
  3. Import the `patch_all` function from the `aws_xray_sdk.core` package and call it during the function's initialization to automatically instrument the AWS SDK client.Answer
  4. D
    Manually inject the `X-Amzn-Trace-Id` header into the DynamoDB client request parameters for every put item operation.

Answer

Import the `patch_all` function from the `aws_xray_sdk.core` package and call it during the function's initialization to automatically instrument the AWS SDK client.
Calling `patch_all` from the AWS X-Ray SDK for Python automatically instruments supported libraries, including Boto3. This enables the X-Ray SDK to intercept downstream DynamoDB API calls, create subsegments, and automatically propagate the tracing context without manual header manipulation.

Step-by-Step Solution

1
Analyze the missing component of the trace map.
The Lambda function is successfully traced, but calls to DynamoDB using the Boto3 library do not generate downstream segments, indicating a client-side instrumentation issue.
By default, enabling active tracing on Lambda only traces the Lambda service and function execution, not the library calls within the code.
2
Select the correct instrumentation method for Python's Boto3 SDK.
Identify that the AWS X-Ray SDK for Python provides patch functions (such as `patch_all` or `patch`) to intercept calls made by Boto3.
Patching Boto3 is the standard way to hook into the client request lifecycle and automatically generate subsegments for downstream AWS services.
3
Implement the patch function at the initialization phase.
Place the `patch_all()` call at the top of the Lambda function file, before Boto3 clients are instantiated.
Calling `patch_all()` before creating clients ensures all subsequent clients are properly wrapped and instrumented for distributed tracing.

Key Concept

AWS SDK client instrumentation in Python using the AWS X-Ray SDK is required to capture and trace downstream AWS service calls.
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Topics

Instrumenting Distributed Tracing with AWS X-Ray

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