concept correlation ID in category microservice
This is an excerpt from Manning's book Spring Microservices in Action.
Log correlation— How do you tie together all the logs produced between services for a single user transaction? With this pattern, we’ll look at how to implement a correlation ID, which is a unique identifier that will be carried across all service calls in a transaction and can be used to tie together log entries produced from each service.
TrackingFilter—The TrackingFilter will be a pre-filter that will ensure that every request flowing from Zuul has a correlation ID associated with it. A correlation ID is a unique ID that gets carried across all the microservices that are executed when carrying out a customer request. A correlation ID allows you to trace the chain of events that occur as a call goes through a series of microservice calls.
To implement this, you’re going to build a set of three classes into each of your microservices. These classes will work together to read the correlation ID (along with other information you’ll add later) off the incoming HTTP request, map it to a class that’s easily accessible and useable by the business logic in the application, and then ensure that the correlation ID is propagated to any downstream service calls.
The first class you’re going to build is the UserContextFilter class. This class is an HTTP servlet filter that will intercept all incoming HTTP requests coming into the service and map the correlation ID (and a few other values) from the HTTP request to the UserContext class. The following listing shows the code for the UserContext class. The source for this class can be found in licensing-service/src/main/java/com/thoughtmechanix/licenses/utils/UserContextFilter.java.