Using DI containers

A DI container is a library that injects a service into the client. A DI container provides extra functionality other than injecting dependencies, such as the following:

• Registering the classes that need to be injected (registering the services)
• Implementing how the services need to be instantiated
• Instantiating what has already been registered
• Managing the created service lifetime

Let’s clarify a DI container role with an example from the previous code. We have the logger service being injected, but who is responsible for this?

There is a DI container called Microsoft.Extensions.DependencyInjection that will inject _logger. This happened in the first line of Program.cs, as illustrated here:

var builder = WebApplication.CreateBuilder(args);

This previous method call registers a default logger. Unfortunately, while we can see the code in the .NET source code, it is not obvious in our Program.cs source code. In fact, the...