Intro

• Provides tracing of requests as they travel through different AWS services to
  • identify performance bottlenecks
  • pinpoint errors
  • understand dependencies in micro-services
• Useful for micro-services (distributed) applications where debugging is hard
• Ability to trace every request or a sample of requests
• Compatible with
  • Lambda
  • Elastic Beanstalk
  • ECS
  • ELB
  • API Gateway
  • EC2 instances or on-premise servers
• Security
  • IAM for authorization
  • KMS for encryption at rest
• Ability to send traces across accounts (allows to have a central account for application tracing)

Enabling X-Ray

• Use the AWS X-Ray SDK in your code (little code modification)
• Install X-Ray daemon if your application is running on EC2 or on-premise server. For other services, enable X-Ray integration (X-Ray daemon is already running).
• Configure IAM permissions for the X-Ray daemon or AWS service to write data to X-Ray.

How traces are sent

• X-Ray SDK captures calls to AWS services as well as other HTTP / HTTPS / Database / Queue calls.
• X-Ray SDK sends traces to X-Ray daemon through UDP on port 2000 (configure port mappings and network settings in the task definition file to allow the application to communicate with the X-Ray daemon container)
• X-Ray daemon batches the traces and sends them to X-Ray service every second.

X-Ray instrumentation in code

• Only configuration change is required in the code
• Can modify the application code to customize and annotate the traces sent by X-Ray SDK.

Terminologies

• Segments: data sent by each application / service
• Subsegments: provide more granular timing information and details about downstream calls (to AWS services, HTTP API or an SQL DB) that your application makes to fulfill the original request.
• Trace: segments collected together to form an end-to-end trace
• Annotations: indexed key-value pairs attached to traces for search capability and filtering traces using filter expressions
• Metadata: non-indexed key-value pairs attached to traces