PowerBi - how to authenticate to app.powerbi.com silently - powerbi

Question

I have tried the method outlined in the Microsoft docs
which involves creating an app in Active Directory and then having code something very similar to:
var authContextUrl = "https://login.windows.net/common/oauth2/authorize";
var authenticationContext = new AuthenticationContext(authContextUrl);
var redirectUri = "https://dev.powerbi.com/Apps/SignInRedirect";
var pp = new PlatformParameters(PromptBehavior.Auto);
var result = authenticationContext.AcquireTokenAsync(PowerBiApiResource, clientId, new Uri(redirectUri), pp).GetAwaiter().GetResult();
if (result == null)
{
throw new InvalidOperationException("Failed to obtain the PowerBI API token");
}
var token = result.AccessToken;
return token;
I got this code working but it always insisted on prompting for a username and password, which is a problem for a function app.
I have also tried the approach in the silent function specified here
https://community.powerbi.com/t5/Developer/Data-Refresh-by-using-API-Need-Steps/m-p/209371#M6614
static string getAccessTokenSilently()
{
HttpWebRequest request = System.Net.HttpWebRequest.CreateHttp("https://login.windows.net/common/oauth2/token");
//POST web request to create a datasource.
request.KeepAlive = true;
request.Method = "POST";
request.ContentLength = 0;
request.ContentType = "application/x-www-form-urlencoded";
//Add token to the request header
request.Headers.Add("Authorization", String.Format("Bearer {0}", token));
NameValueCollection parsedQueryString = HttpUtility.ParseQueryString(String.Empty);
parsedQueryString.Add("client_id", clientID);
parsedQueryString.Add("grant_type", "password");
parsedQueryString.Add("resource", resourceUri);
parsedQueryString.Add("username", username);
parsedQueryString.Add("password", password);
string postdata = parsedQueryString.ToString();
//POST web request
byte[] dataByteArray = System.Text.Encoding.ASCII.GetBytes(postdata); ;
request.ContentLength = dataByteArray.Length;
//Write JSON byte[] into a Stream
using (Stream writer = request.GetRequestStream())
{
writer.Write(dataByteArray, 0, dataByteArray.Length);
var response = (HttpWebResponse)request.GetResponse();
var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
dynamic responseJson = JsonConvert.DeserializeObject<dynamic>(responseString);
return responseJson["access_token"];
}
}
This code doesn't work.
Also this has issues, although I haven't tried it:
https://learn.microsoft.com/en-us/power-bi/developer/get-azuread-access-token
There doesn't appear to be anything up to date available that works that explains how to do this. Does anyone know how?

Answer 1

This is the best I've got so far. I have to create the application in AD using https://dev.powerbi.com/apps and then login using a powerbi pro userid and password, using the following code:
public static string GetPowerBiAccessToken(string tenantId, string clientId, string userId, string password)
{
var url = $"https://login.windows.net/{tenantId}/oauth2/token";
var request = (HttpWebRequest)WebRequest.Create(url);
request.KeepAlive = true;
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
var dataToPost = new Dictionary<string,string>
{
{"client_id", clientId},
{"grant_type", "password"},
{"resource", PowerBiApiResource},
{"username", userId},
{"password", password},
{"redirect_uri", "https://dev.powerbi.com/Apps/SignInRedirect" }
};
var postData = string.Empty;
foreach (var item in dataToPost)
{
if (!string.IsNullOrEmpty(postData))
postData += "&";
postData += $"{item.Key}={item.Value}";
}
var dataByteArray = System.Text.Encoding.ASCII.GetBytes(postData);
request.ContentLength = dataByteArray.Length;
using (var writer = request.GetRequestStream())
{
writer.Write(dataByteArray, 0, dataByteArray.Length);
}
var response = (HttpWebResponse)request.GetResponse();
var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
var responseJson = JsonConvert.DeserializeObject<dynamic>(responseString);
return responseJson["access_token"];
}
(P.S. I appreciate the request part of this code could be much better but having spent over 2 days trying to work this out, I'm just glad to have something that is working right now. Also the redirectUrl matches the one in my app, I'm not sure if its essential or not).
In the event of errors, I used Fiddler 4 to tell me exactly what the error was rather than just getting 400 or 401 in the app.