Redirect URI with Client Credential Flow

Question

I am looking into using MSAL and client credential flow, however, there is one thing I don't fully understand.

In the example provided by Microsoft: https://github.com/Azure-Samples/active-directory-dotnetcore-daemon-v2/blob/master/daemon-console/Program.cs

The following code is used to get an access token:

var clientCredentials = new ClientCredential(_clientSecret);
var app = new ConfidentialClientApplication(_clientId, _authority, "https://daemon", clientCredentials, null, new TokenCache());
string[] scopes = new string[] { "https://graph.microsoft.com/.default" };
AuthenticationResult result = await app.AcquireTokenForClientAsync(scopes);

Whats with the redirectUri in this case?

I have tried different values as the redirectUri and it seems to work either way... but if I add a relative path or null it fails to obtain a token. What is this value supposed to be?

For a console application it makes little sense to listen on an URL, however, the documentation for ConfidentialClientApplication says that it is required.

Answer 1

To request access token with client credential flow , app will send HTTP POST token request to Azure AD's token endpoint with app's credential , AAD will return access token in response , redirect url is not need in this scenario . According to source code , the redirect url is not used also:

private async Task<AuthenticationResult> AcquireTokenForClientCommonAsync(IEnumerable<string> scopes, bool forceRefresh, ApiEvent.ApiIds apiId, bool sendCertificate)
{
    Authority authority = Instance.Authority.CreateAuthority(ServiceBundle, Authority, ValidateAuthority);
    AuthenticationRequestParameters parameters = CreateRequestParameters(authority, scopes, null,
        AppTokenCache);
    parameters.IsClientCredentialRequest = true;
    parameters.SendCertificate = sendCertificate;
    var handler = new ClientCredentialRequest(
        ServiceBundle,
        parameters,
        apiId,
        forceRefresh);

    return await handler.RunAsync(CancellationToken.None).ConfigureAwait(false);
}

But you should provide a valid url when initializing the ConfidentialClientApplication at this point .