Configure HttpClient to use a service to populate the authentication header?

user_879553 0
Viewed 1050

I want to use a typed HTTP client so I register it like this in the ServiceCollection

services.AddHttpClient<ApiService>();

All the requests that the client makes, must be authenticated. So I'd need to slightly modify the snippet above to this:

services.AddHttpClient<ApiService>(c =>
{
    c.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "");
});

The bearer token needs to be renewed all 5 minutes, so I need to create service that needs dependencies like an HttpClient (to authenticate and get the token) and a MemoryCache (to store the token as long it's valid).

The problem is, as you can see, this is still in the phase before the service provider is built, so I can't resolve anything at this point... What are my options here?

asp.net-core .net-core dependency-injection c#
2 Answers

You can access the ServiceProvider like this:

services.AddHttpClient<ApiService>(provider, c) =>
{
    var token = provider.GetRequiredService<MyTokenService>().GetToken();
    c.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
});

If you don't have access to the overload with the provider you will need to update your dependencies. AddHttpClient will register a transient client so the func ("factory method") will run each time you inject it somewhere.

user_11410890

Could you do this in the constructor of ApiService, also passing the authentication service to that via DI?

e.g.

public class ApiService
{
    private readonly HttpClient client;

    public ApiService(HttpClient client, IAuthenticationService auth)
    {
        // configure client here

        this.client = client;
    }
}
user_81993620
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