Client Credentials Usage

Configuration file section

1. Add the following configuration section to your appsettings.json files, and populate it appropriately.

  "ClientCredentialsConfiguration": {
    "clientName": "",
    "authority": "",
    "clientId": "",
    "grantTypes": [ "client_credentials" ],
    "scopes": [ ],
    "secretType": "private_key_jwt:RsaPrivateKeyJwtSecret",
    "rsaPrivateKey": "",
    "rsaKeySizeBits": 4096,
    "privateJwk": "",
    "Apis": [
      {
        "Name": "", // Tip:  Use nameof(YourService)
        "Url": ""
      }
    ],
    "refreshTokenAfterMinutes":  8  // Set approx 20% less than lifetime of access token
  }

PS: Please be aware that the Authority must end with connect/token.

Client Credentials using Keypairs

1. Add package 'Fhi.ClientCredentialsKeypairs' to your project

2. In your Program.cs file, or if older Startup.cs, add the following code section (for the outgoing interfaces):

    var clientCredentialsConfiguration = services.AddClientCredentialsKeypairs(Configuration);
    services.AddHttpClient(nameof(YourService), c =>
    {
       c.Timeout = new TimeSpan(0, 0, 0, 10);
       c.BaseAddress = clientCredentialsConfiguration.UriToApiByName(nameof(YourService));
    })
    .AddHttpMessageHandler<HttpAuthHandler>()
    .AddTypedClient(c => RestService.For<IExternalApi>(c, new RefitSettings
    {
       ContentSerializer = new SystemTextJsonContentSerializer(services.DefaultJsonSerializationOptions())
    }));

replacing YourService with the service you have done for accessing the external api, and replace IExternalApi with the Refit interface for whatever external api you want to access.

For usages of Refit that uses an interface (in this example IMyService is the interface that Refit will implement), the code would look something like this:

services
    .AddRefitClient<IMyService>()
    .ConfigureHttpClient(c =>
    {
        c.BaseAddress = clientCredentialsConfiguration.UriToApiByName(nameof(IMyService));
    })
    .AddHttpMessageHandler<HttpAuthHandler>();

The Configuration property is the injected IConfiguration property from the Startup.cs file.

If you don't use Refit, you can just skip the last part, and get the named client from the injected HttpFactory in your service. It will still have the authenticationhandler, so you don't need to do anything more there to get the bearer token. It will be added automatically.

Client Credentials using Client Secrets

If you want to disable the authorization for some reason, you can add another property named Enable to the ClientCredentialsConfiguration, it is default true.

2. Add package Fhi.ClientCredentialsUsingSecrets to your project
3. In your Program.cs file, create an instance of the ClientCredentialsSetup class using an IConfiguration parameter.
4. Using the created instance call the method ConfigureServices.

Calling endpoints that does not required authentication

In some cases we might wish to call an API before we are authenticated (health endpoints, kodeverk, etc..).

To make the HttpAuthHandler not add authentication headers to a single request you can add an Option to the request with the key name "Anonymous":

var request = new HttpRequestMessage();
request.Options.TryAdd("Anonymous", "");

or in Refit:

[Get("/info")]
Task<string> GetInfo([Property("Anonymous")] string anonymous = "");