ASP.NET Core Logging with Correlation IDs via Middleware
In modern distributed systems, a single user action can trigger a cascade of requests across multiple microservices. When something goes wrong, tracing that single action through a sea of log entries can feel like finding a needle in a haystack. This is where correlation IDs become an indispensable tool for observability.
A correlation ID is a unique identifier that follows a request from start to finish, even as it hops between services. By including this ID in every log message related to that request, you can easily filter and piece together the entire transaction.
The most effective way to implement this in ASP.NET Core is with custom middleware. Let’s dive into how to build it.
Why Middleware is the Perfect Solution
The ASP.NET Core request pipeline is a series of components, or middleware, that process an HTTP request. By creating our own middleware and placing it early in the pipeline, we can ensure that:
- Every request is intercepted: No request gets processed without a correlation ID.
- Logic is centralized: We avoid cluttering our controllers or services with repetitive logging code.
- It’s set up once: Once the middleware is registered, the correlation ID is available for the entire scope of the request.
This approach is clean, efficient, and aligns perfectly with the ASP.NET Core design philosophy.
Building the Correlation ID Middleware
First, we’ll create the middleware component itself. This class will inspect incoming request headers for an …
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