Distributed Tracing is a method used to debug or monitor applications built using microservices architecture. It provides developers with the capacity to monitor requests from clients. Basically, it helps in monitoring and understanding your applications systematically by tracking and visualizing all details from end to end of a request.
Principle of Distributed Tracing
In a microservices architecture, a request will be routed from one service to another. The trip it takes through the services is considered a trace. Each stop it makes (service it visits) within the trace is considered a span. Span will record timestamp, duration and metadata for combinations of spans forming a graph and forming a tree structure that represents the journey of the request. Distributed tracing systems are responsible for collecting, storing and analyzing these spans.
Significance of Distributed Tracing
- Identification of bottlenecks in the system
- Facilitating debugging of the system
- Providing reliable analytics
- Monitoring the health of the application
- Offering a clear overview of an application’s architecture
AWS X-Ray and Distributed Tracing
Amazon AWS provides a distributed tracing system known as X-Ray. AWS X-Ray provides an end-to-end view of requests as they travel through your application, and shows a map of your application’s underlying components. It helps developers analyze and debug production, distributed applications, such as those built using a microservices architecture.
To use AWS X-Ray for distributed tracing you need to:
- Install the X-Ray SDK in your application: The SDK provides hooks into the application code.
- Use the AWS X-Ray service to receive and store the application data: This is done by running the X-Ray service daemon alongside the application.
Integration of X-Ray with AWS services
AWS X-Ray works with applications running on EC2 instances, ECS containers, Beanstalk, Lambda and many more services. For example, here is how you will do it in a Lambda function:
python
import aws_xray_sdk.core
def lambda_handler(event, context):
…
aws_xray_sdk.core.patch_all() # Enables x-ray
…
Viewing the Trace data
The X-Ray console shows a service map. This map shows latency bottlenecks, traffic bottlenecks and error rates across microservices.
Comparison with Other Tracing Tools
AWS X-Ray versus Jaeger or Zipkin, it’s notable that X-Ray fully integrates with other AWS services, presents a convenient pay-as-you-go model, and offers neat features tied to AWS, such as Lambda insights. On the other hand, Jaeger and Zipkin, being open-source, do not tie the user to a specific cloud vendor, offer flexibility and a broad user-based community for help.
Summary
Distributed tracing is an essential tool for debugging and monitoring applications, and AWS X-Ray is a versatile choice for implementing distributed tracing, given its convenient integration with AWS services.
It is worthy to note that the AWS Certified Developer – Associate (DVA-C02) exam tests the candidate’s understanding of distributed tracing and AWS X-Ray to an extent, given the topic’s relevance to developing effective and efficient applications on AWS. Therefore, knowing how to implement and use distributed tracing using AWS X-Ray is vital for clearing the examination.
Practice Test
True or False: Distributed tracing helps in understanding the flow of data and execution of applications.
- True
- False
Answer: True
Explanation: Distributed tracing allows you to trace all requests from their source down to their lowest level of detail. This helps identify bottlenecks and pain points in your software system.
What is the primary purpose of AWS X-Ray?
- a) Server virtualization
- b) Managed database service
- c) Error reporting
- d) Distributed request tracing
Answer: d) Distributed request tracing
Explanation: AWS X-Ray is a service that gathers data about requests that your application serves, and provides tools you can use to view, filter, and gain insights into that data to identify issues and opportunities for optimization.
Can distributed tracing and AWS X-Ray be used together to monitor and troubleshoot applications and microservices?
- a) Yes
- b) No
Answer: a) Yes
Explanation: AWS X-Ray is a service that provides distributed tracing, helping developers analyze and debug production, distributed applications, such as those built using a microservices architecture.
True or False: AWS X-Ray only supports applications running on AWS.
- True
- False
Answer: False
Explanation: AWS X-Ray can support applications running both on AWS and on-premises. It provides an end-to-end view of requests as they travel through the application, and shows a map of the application’s underlying components.
Which AWS service helps you in analyzing and debugging your distributed microservices applications?
- a) Amazon CloudFront
- b) Amazon API Gateway
- c) AWS X-Ray
- d) Amazon Elasticsearch Service
Answer: c) AWS X-Ray
Explanation: AWS X-Ray helps developers analyze and debug distributed applications, such as those built using a microservices architecture.
Which of the following languages are supported by AWS X-Ray SDKs? (Multiple select)
- a) Python
- b) Java
- c) Ruby
- d) Swift
Answer: a) Python, b) Java, c) Ruby
Explanation: The AWS X-Ray SDKs currently support Java, .NET, Node.js, Python, Ruby, and Go.
True or False : Distributed tracing mainly focuses on tracing processing within a single request.
- True
- False
Answer: False
Explanation: Distributed tracing is designed to enable tracking requests as they propagate across multiple services, not just within a single service.
Is it true that distributed tracing allows individuals to monitor applications on a single machine only?
- a) Yes
- b) No
Answer: b) No
Explanation: Distributed tracing allows monitoring of applications across multiple machines, providing helpful insights into larger, complex systems.
Which AWS service allows you to collect, filter, and analyze APi call logs for AWS services?
- a) AWS X-Ray
- b) AWS Lambda
- c) Amazon CloudTrail
- d) Amazon CloudWatch
Answer: c) Amazon CloudTrail
Explanation: Amazon CloudTrail allows you to log, continuously monitor, and retain account activity related to actions across your AWS infrastructure.
True or False: AWS X-Ray supports tracing of SQL queries in your application.
- True
- False
Answer: True
Explanation: AWS X-Ray provides insights into SQL queries within your application by recording the SQL query in the X-Ray trace.
Interview Questions
What is distributed tracing in AWS?
Distributed tracing in AWS enables developers to analyze and debug their microservices applications by tracking each request made to these applications and recording detailed data about these requests like latency, state, CPU usage, etc.
Which AWS service is primarily used for distributed tracing?
AWS X-Ray is primarily used for distributed tracing for applications running in AWS.
Can you use AWS X-Ray with any AWS service?
You can use AWS X-Ray with any service that is integrated with it, for example, AWS Lambda, Amazon EC2, Amazon ECS, and many others.
What component of AWS X-Ray collects data and sends it to the X-Ray service?
The X-Ray SDK is the component that collects data and sends it to the X-Ray service.
What is a trace in AWS X-Ray?
In AWS X-Ray, a trace is a set of segment documents that provides a detailed map of the entire path that a request takes through an application.
What is a segment in AWS X-Ray?
A segment in AWS X-Ray provides the resource-level view of work done and includes details about the work, including start time, end time, and subsegments.
Can you use AWS X-Ray with applications that do not run on AWS?
Yes, you can use AWS X-Ray with applications that do not run on AWS.
What is a service graph in AWS X-Ray?
A service graph is a visual representation of your application showing the relationship between all its components.
Do you need to modify your code to trace requests in AWS X-Ray?
Yes, to trace requests to and from your application, you need to modify your code to include the AWS X-Ray SDK.
What is a subsegment in AWS X-Ray?
In AWS X-Ray, a subsegment provides more granular timing information and details about downstream calls, retries, and nested calls that your application makes.
How can one use sampling rules in AWS X-Ray?
Sampling rules in AWS X-Ray can be used to modify the amount of data that is collected by choosing which requests to trace.
Can AWS X-Ray trace SQL queries?
Yes, AWS X-Ray can trace SQL queries. The X-Ray SDK for Java can record SQL queries in subsegments as part of the segment data.
What do annotations in AWS X-Ray do?
Annotations in AWS X-Ray provide a way to add indexed metadata to a trace, allowing you to filter or group the traced requests based on the custom criteria.
What’s the maximum number of annotations and metadata that can be attached to an AWS X-Ray trace?
An AWS X-Ray trace can hold up to 50 annotations and metadata.
What are some data sources that can be included in AWS X-Ray tracing?
AWS X-Ray tracing can include data sources such as request and response data, HTTP method, user agent, and URL path, among others.
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