Authorize WebApp to ADFS in order to access Dynamics CRM Web API

Question

I have a web application that needs to speak with Dynamics CRM 365 Web API. The Dynamics CRM is configured as a Relying Party on ADFS. The server is Windows Server 2016 and ever

Answer 1

At the end i had to use a system user and send it's credentials in my oAUth request using the code below in order to acquire a valid token:

namespace TestApp.App_Start {
public class CrmWebApiClient
{
    private HttpClient _httpClient;

    public CrmWebApiClient()
    {       
        _httpClient = new HttpClient();
        _httpClient.BaseAddress = new Uri("https://crmUrl");
        _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        _httpClient.DefaultRequestHeaders.Add("OData-MaxVersion","4.0");
        _httpClient.DefaultRequestHeaders.Add("OData-Version", "4.0");
    }

    internal async Task Initilize()
    {
        try
        {

            var tokenClient = new HttpClient();             
            var content = new FormUrlEncodedContent(new[] {
                new KeyValuePair("client_id",_clientID),
                new KeyValuePair("client_secret",_clientSecret),
                new KeyValuePair("resource",_urlOfResource),
                new KeyValuePair("username",_usernameOfSystemUser),
                new KeyValuePair("password",_passwordOfSystemUser),
                new KeyValuePair("grant_type","password"),
            });
            var res = tokenClient.PostAsync("https://adfsUrl/adfs/oauth2/token", content);
            var respo = res.Result.Content.ReadAsStringAsync().Result;
            var accesstoken = JObject.Parse(respo).GetValue("access_token").ToString();

            _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accesstoken);

        }
        catch (Exception ex)
        {
            Trace.WriteLine($"Exception when requesting the bearer token from ADFS: {ex.Message} - {ex.InnerException?.Message}");
        }

    }

    internal async Task GetAccountsAsync()
    {
        var result = string.Empty;
        try
        {
            result = _httpClient.GetStringAsync("/api/data/v8.0/accounts").Result;

        }
        catch (Exception ex)
        {
            Trace.WriteLine($"Exception when calling the CRM api: {ex.Message} - {ex.InnerException?.Message}");
        }
        return result;
    }
}
}


// Use the above class like that
var httpClient = new CrmWebApiClient();
httpClient.Initilize().Wait();
var result = httpClient.GetAccountsAsync().Result;