Environment Variables for AWS Lambda X-Ray Service
Question
Your team is developing a set of Lambda functions.
They need to debug the Lambda functions using the X-Ray service.
Which of the following are environment variables which AWS Lambda uses to communicate with the X-Ray service? Choose 3 answers from the options given below.
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Answer - A, B and C.
The AWS Documentation mentions the following.
AWS Lambda uses environment variables to facilitate communication with the X-Ray daemon and configure the X-Ray SDK.
_X_AMZN_TRACE_ID: Contains the tracing header, which includes the sampling decision, trace ID, and parent segment ID.
If Lambda receives a tracing header when your function is invoked, that header will be used to populate the _X_AMZN_TRACE_ID environment variable.
If a tracing header was not received, Lambda will generate one for you.
AWS_XRAY_CONTEXT_MISSING: The X-Ray SDK uses this variable to determine its behavior in the event that your function tries to record X-Ray data, but a tracing header is not available.
Lambda sets this value to LOG_ERROR by default.
AWS_XRAY_DAEMON_ADDRESS: This environment variable exposes the X-Ray daemon's address in the following format: IP_ADDRESS:PORT.
You can use the X-Ray daemon's address to send trace data to the X-Ray daemon directly, without using the X-Ray SDK.
For more information on using Lambda with X-Ray, please refer to the below URL-
https://docs.aws.amazon.com/lambda/latest/dg/lambda-x-ray.htmlSure, I'd be happy to provide a detailed explanation!
When you enable AWS X-Ray for your Lambda functions, you need to make sure that the functions are properly instrumented with the X-Ray SDK. Once instrumented, your functions can automatically record tracing data and send it to the X-Ray service for analysis.
In addition to instrumenting your functions, you also need to set a few environment variables so that AWS Lambda can communicate with the X-Ray service. Here are the three environment variables that you need to set:
_X_AMZN_TRACE_ID: This environment variable contains the tracing header that is used to propagate tracing information between services. When a Lambda function is invoked, the _X_AMZN_TRACE_ID environment variable is automatically set to the tracing header that was sent with the incoming request.
AWS_XRAY_CONTEXT_MISSING: This environment variable specifies how the X-Ray SDK should behave if tracing information is not available. The default value is "LOG_ERROR", which means that the SDK will log an error message if tracing information is missing. You can also set this variable to "RUNTIME_ERROR" to make the SDK throw a runtime error if tracing information is missing.
AWS_XRAY_DAEMON_ADDRESS: This environment variable specifies the address and port number of the X-Ray daemon that is running on your EC2 instances or containers. The X-Ray daemon is responsible for receiving tracing data from your Lambda functions and sending it to the X-Ray service. If you don't set this variable, the SDK will use the default address and port (127.0.0.1:2000).
Note that the answer "AWS_LAMBDA_XRAY" is not a valid environment variable. However, it is worth noting that you can also enable X-Ray tracing for your Lambda functions by setting the "TracingConfig" property of your Lambda function's configuration to "Active". This will automatically set the environment variables described above and enable tracing for your function.
