Have you ever had to deal with a bug or issue in a distributed system architecture (microservice architecture) or large scale scalable system where you have no idea how and where the transaction is flowing from component to component? Yes you are not alone, and it is not super complicated to solve this problem as well!

Thanks to Correlation ID, a Correlation ID (Correlation Identifier) is a unique identifier assigned to a specific transaction or a sequence of related events across different components or services in a distributed system.

Lets understand the problem first:

Problem

Lets assume you are having micro service architecture for your application, and typically a API call from client comes to a MicroService and based on requirement that service is calling / executing the required actions from other MicroServices and return the result.

You are also adding relevant logs for all your transactions in these API calls, now the problem is at any time you are checking these logs, you will be buried under lot of logs since there could be multiple clients are using your APIs right?

Solution

A Correlation ID is a unique identifier that is added to the very first interaction (incoming request) to identify the context and is passed to all components that are involved in the transaction flow. Correlation ID becomes the glue that binds the transaction together and helps to draw an overall picture of events.

Assigning correlation id to each transaction or in our case API. For an HTTP Request, Correlation ID is typically passed in the header. So whenever you are initiation the API request pass the UUID as correlation id in header.

But how you would use it?

So once you get this correlation id in request, you can use this to all in your logs and also forward same to next request you are forwarding to next service.

This way this ID becomes the glue that binds the transaction together and helps to draw an overall picture of events.

It is recommended to return this same id with response as well to track a single end to end customer transaction flow through the various components.

In a Nutshell

Correlation IDs might seem like a small addition, but their impact is colossal. They untangle the complexity of distributed systems, making troubleshooting feel like a well-directed movie plot rather than a wild goose chase. Embrace the Correlation ID, and watch chaos bow to the power of structured traceability.

So, remember: start early, propagate consistently, log diligently, and unlock the full potential of Correlation IDs. Your future self, and your fellow developers, will thank you for the gift of clarity in the face of complexity.