X-Ray

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XRay

About

• X-Ray is an AWS offering which allows to in the following

  • Troubleshoot performance.

  • Understand dependencies in microservices architecture.

  • Review request behavior.

  • Find errors and exceptions.

  • SLA requirements can be accessed.

  • Throttling issues.

  • Identify users that are impacted

• X-Ray service map gives details about the api flow, service interaction in a nice graphical visual form, giving interesting insights.

Compatibility

• Can be used along with many AWS services

  • Lambda

  • Elastic Beanstalk

  • ECS

  • ELB

  • API Gateway

  • EC2 instances or any application server (even on premise)

Working

• X-Ray leverages tracing

• Tracing is a end to end way of following a request.

• Each component dealing with the request adds its own trace.

• Tracing is made of segments.

• Annotations can be added to trace to provide extra-information

• Ability to trace

  • Every request

  • Sample request (as a % for example or a rate per minute)

• X-Ray Security

  • IAM Authorization

  • KMS for encryption at rest

Enable X-Ray

• To enable X-Ray, one must import the AWS X-Ray SDK.

• Install X-Ray daemon or enable X-Ray AWS integration in the AWS service.

• All application should have IAM rights to write data to X-Ray.

• Once all the above is done, X-Ray daemon will send batch every 1 second to AWS X-Ray.

• For lambda, X-Ray Active Tracing should be enabled in lambda function's configuration.

X-Ray Instrumentation

• Instrumentation means the measure of product's performance, diagnose errors, and to write trace information.

• To instrument your application code, use the X-Ray SDK.

• Mostly configuration changes are only required, however one can modify the application using interceptors, filters, handlers etc.

X-Ray Concepts

• Segments

  • Each application/service will send them.

• Sub Segments

  • To provide more fine grain details in your segment.

• Trace

  • Segments collected together to form an end-to-end trace.

• Sampling

  • To decrease the amount of requests send to X-Ray, reduce cost.

  • It allows to control the amount of data that you record.

  • Sampling rules can be modified without changing code.

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

  • One request per second is the reservoir, which ensures that atleast one trace is recorded each second as long as the service is serving requests.

  • Five percent is the rate at which additional requests beyond the reservoir are sampled.

  • One can define their own sampling rules, along with reservoir and rate.

• Annotations

  • These are key-value pairs to index traces and use the filters.

• Metadata

  • Key-Value pairs, not indexed, not used for searching

X-Ray Daemon

• X-Ray daemon/agent has a config to send traces cross-account. - Make sure the IAM permissions are correct. The agent will assume the role.

• This allows to have central account for application tracing.

X-Ray APIs

• PutTraceSegments: Upload segment documents to AWS X-Ray

• PutTelemetryRecords: Used by the AWS X-Ray daemon to upload the telemetry.

• GetSamplingRules: Retrieving all sampling rules.

• GetServiceGraph: Retrieves main graph

• BatchGetTraces: Retrieve a list of traces specified by ID. Each trace is a collection of segment documents that originates from a single request.

• GetTraceSummaries: Retrieve IDs and annotations for traces available for specified time frame using optional filter. To get full traces, pass the trace IDs to BatchGetTraces.

• GetTraceGraph: Retrieves a service graph for one or more specific trace IDs.

• X-Ray Daemon should have an IAM policy authorizing so that for the above API calls to retrieve the details.

ECS and X-Ray

• EC2 instance : X-Ray Container as Daemon

  • Application container will run along with this daemon container per EC2 instance.

• ECS cluster : X-Ray Container as SideCar pattern

  • X-Ray container will run alongside application container.

  • Both will connect to each other from networking context.

• ECS Fargate cluster

  • Similar to ECS cluster, the fargate task will have both the app container and X-Ray SideCar Container.