Some X-Ray notes

• Segment and subsegment in Lambda
• SQS to Lambda

| AWS X-Ray Daemon | aws/aws-xray-daemon | | AWS X-Ray SDK (Python) | aws/aws-xray-sdk-python |

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Segment and subsegment in Lambda

• Summary of facade segment and new segment/subsegments in Lambda.

  • aws/aws-xray-sdk-node#148
  • aws/aws-xray-sdk-node#160

• AWSXray.getSegment() returns the root segment from the previous invocation.

  • https://theburningmonk.com/2017/06/aws-x-ray-and-lambda-the-good-the-bad-and-the-ugly/

• The in_progress subsegment is discarded in favor of the completed subsegment.

  • i.e. (in_progress === undefined)
  • Ref: https://docs.aws.amazon.com/xray-sdk-for-nodejs/latest/reference/

• By default, the X-Ray SDK records the first request each second, and five percent of any additional requests.

• Sampling rules https://docs.aws.amazon.com/xray/latest/devguide/xray-console-sampling.html#xray-console-sampling-options

• Segment doc max 64 kb https://docs.aws.amazon.com/xray/latest/devguide/xray-api-segmentdocuments.html

• Dynamically adjusting X-Ray sampling rules https://aws.amazon.com/blogs/mt/dynamically-adjusting-x-ray-sampling-rules/

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SQS to Lambda

Update:

AWS X-Ray adds trace linking for event-driven applications built on Amazon SQS and AWS Lambda (https://aws.amazon.com/about-aws/whats-new/2022/11/aws-x-ray-trace-linking-event-driven-applications-amazon-sqs-lambda/)

Previous approach:

(Outdated): SQS supports X-Ray tracing but it does not propagate the trace to a Lambda function. Lambda always starts a new trace.-

See:

• aws-xray-sdk-node: aws/aws-xray-sdk-node#208.
  • Possible workaround: Create a new segment for the lambda to link to the parent (sqs)
• aws-xray-sdk-dotnet: aws/aws-xray-sdk-dotnet#110

Workaround:

• Create a new segment to replace the facade segment created by Lambda, and retrieve the trace ID and parent ID from the trace header (from the SQS segment).
• Example: xray-sqs-to-lambda/handler.ts