AWS Lambda Logging, Monitoring, and Tracing

Logging with CloudWatch Logs

• Lambda functions automatically store execution logs in CloudWatch Logs.
• Requires Lambda execution role with IAM policy authorizing write access to CloudWatch Logs.
• Included in the Lambda basic execution role.

Monitoring with CloudWatch Metrics

• Metrics are available in the CloudWatch Metrics UI or Lambda UI.
• Key metrics include:
  • Invocations: The number of times your function is invoked.
  • Duration: The execution time of your function.
  • Concurrent Executions: The number of instances serving requests at a given time.
  • Error Counts: The number of errors thrown by your function.
  • Success Rate: The percentage of successful invocations.
  • Throttles: The number of Lambda invocation attempts that were throttled.
  • Async Delivery Failures: Failures in asynchronous invocation.
  • Iterator Age (for Kinesis/DynamoDB streams): The age of the last record processed.

Tracing with AWS X-Ray

• Enable active tracing in Lambda configuration to use X-Ray.
• Requires the Lambda function to have the correct IAM execution role for X-Ray.
• Managed policy for X-Ray: AWSXRayDaemonWriteAccess.
• Important environment variables:
  • AWS_XRAY_DAEMON_ADDRESS: IP and port of the X-Ray daemon.
  • Other X-Ray related environment variables should be recognized.

What is the X-Ray Daemon?

• Role: The X-Ray daemon is a process that runs alongside your Lambda function. It is responsible for:
  • Collecting the trace data generated by your function and the X-Ray SDK
  • Buffering data locally
  • Sending trace data securely to the AWS X-Ray service.
• No direct interaction: You don't need to directly manage or interact with the X-Ray daemon when working with Lambda. AWS handles its execution within the Lambda environment.

Do I need to set up an X-Ray daemon?

• No manual setup: With AWS Lambda, you don't need to set up an X-Ray daemon explicitly. The Lambda service automatically manages an X-Ray daemon process and runs within the Lambda execution environment.

Note for Exam Preparation:

• Remember the environment variable AWS_XRAY_DAEMON_ADDRESS as it may appear on the exam.