Using IWebHostEnvironment in a .NET 8 Class Library

Lacoste

Hey everyone!

So, I was just diving into a new project using .NET 8, and I found myself needing to share some functionality between a web app and a class library. You know how it goes—you're trying to keep things clean, but there's a constant pull to reach for that global context. That's when IWebHostEnvironment popped into my mind.

At first, I thought, "Shouldn’t IWebHostEnvironment be relegated solely to the web project?" It feels a bit odd to drag that dependency into a class library, right? But then I realized there are a few scenarios where it can be super handy. For instance, if you're doing some file management or need to know the environment (like Development or Production), it definitely can simplify things.

However, I still wrestled with whether it might couple my library too tightly to ASP.NET specifics. On one hand, it provides a way to adapt behavior based on the hosting environment. On the other, it can make testing more cumbersome, especially if you're trying to keep your library agnostic.

I started thinking about alternatives, like just passing necessary parameters from the web app into the class library instead of pulling in a whole context. It could lead to cleaner separation of concerns and definitely makes unit testing easier since you’re not worrying about mocking a web environment.

Has anyone else run into this dilemma? How do you manage dependencies on things like IWebHostEnvironment in your class libraries? Do you think it's worth it for the convenience, or do you stick to passing things around to keep your libraries lean and mean? Would love to hear your thoughts!

agnoplastic

Hey! 👋

Great topic—you've basically nailed a dilemma that comes up often when building modular .NET applications.

I’ve faced the same situation and my general rule is: try to keep class libraries as agnostic as possible. Pulling in IWebHostEnvironment directly can definitely be convenient, especially when dealing with file paths (WebRootPath, ContentRootPath) or environment checks—but yeah, it comes at a cost.

What I usually do is define my own abstraction inside the library. Something like:

public interface IAppEnvironment
{
    string EnvironmentName { get; }
    string ContentRootPath { get; }
    // Add only what you actually need
}

Then in the web project, I create an implementation that adapts IWebHostEnvironment to this interface. That way, the library doesn’t know anything about ASP.NET Core, and I can inject a mock easily in unit tests.

Alternatively, if you're only needing one or two pieces of data (like a path or env name), passing them as parameters can often be a better choice. It's simpler and keeps dependencies out of the way.

So in short:

Use interfaces to abstract dependencies

Avoid direct references to ASP.NET Core types in shared libraries

Favor explicit dependencies over pulling the whole context

But yeah—sometimes practicality wins, especially in small internal projects where testability and loose coupling might not be as critical. Still, thinking long-term, I lean toward clean boundaries.

Curious what others are doing too!