X-Ray tracing from SQS to Lambda

#aws #xray #sqs #lambda

SQS supports X-Ray tracing but it does not propagate the trace to Lambda function. Lambda always starts a new trace with an immutable facade segment.

This is a known issue, see:

aws-xray-sdk-node: https://github.com/aws/aws-xray-sdk-node/issues/208
aws-xray-sdk-dotnet: https://github.com/aws/aws-xray-sdk-dotnet/issues/110

Workaround

There were some workaround discussions in the above issues.

The following is a solution I implemented for a demo:

Create a new segment to replace the facade segment created by Lambda, and
assign with the retrieved trace ID and parent ID from the trace header of the SQS segment.

Example in typescript:

import { Handler, SQSEvent, SQSRecord } from "aws-lambda"
import { Segment, setSegment, utils } from "aws-xray-sdk"
...

// Create a new Segment
const traceHeaderStr = sqsRecord.attributes.AWSTraceHeader
const traceData = utils.processTraceData(traceHeaderStr)
const sqsSegmentEndTime = Number(sqsRecord.attributes.ApproximateFirstReceiveTimestamp) / 1000

const lambdaSegment = new Segment(
    functionName,
    traceData.root,
    traceData.parent
)
lambdaSegment.origin = "AWS::Lambda::Function"
lambdaSegment.start_time = lambdaExecStartTime - (lambdaExecStartTime - sqsSegmentEndTime)
lambdaSegment.addPluginData({
    function_arn: functionArn,
    region: sqsRecord.awsRegion,
    request_id: awsRequestId
})

// Set it as the current Segment
setSegment(lambdaSegment)

// Do something

// Close the segment
lambdaSegment.close()