C# WebApi 2 Google Drive authentication on server side

Question

I'm developing a web API that uses the google drive API, on my local machine, first run it redirected me to a google page to authenticate and then worked fine. Now I want to publish my code to Azure, and after I've published it the same function fails, because I could authenticate. How do I perform this authentication on the server?

I've followed the .NET QuickStart (https://developers.google.com/drive/api/v3/quickstart/dotnet), here is my code:

using (var stream =
            new FileStream($@"{dir}\client_secret.json", FileMode.Open, FileAccess.Read))
        {
            var cred = GoogleClientSecrets.Load(stream).Secrets;
            Credentials = GoogleWebAuthorizationBroker.AuthorizeAsync(
                cred,
                Scopes,
                "user",
                CancellationToken.None).Result;
        }
        service = new DriveService(new BaseClientService.Initializer()
        {
            HttpClientInitializer = Credentials,
            ApplicationName = ApplicationName,
        });
}

Answer 1

The tutorial you are following is for a .NET console application this is a native application not a web application. GoogleWebAuthorizationBroker is for use with installed applications. It works on localhost because its able to spawn the browser window on your machine. This wont work in a hosted environment because it cant spawn a web browser on the server.

You should be following this example Web applications

using System;
using System.Web.Mvc;

using Google.Apis.Auth.OAuth2;
using Google.Apis.Auth.OAuth2.Flows;
using Google.Apis.Auth.OAuth2.Mvc;
using Google.Apis.Drive.v2;
using Google.Apis.Util.Store;

namespace Google.Apis.Sample.MVC4
{
    public class AppFlowMetadata : FlowMetadata
    {
        private static readonly IAuthorizationCodeFlow flow =
            new GoogleAuthorizationCodeFlow(new GoogleAuthorizationCodeFlow.Initializer
                {
                    ClientSecrets = new ClientSecrets
                    {
                        ClientId = "PUT_CLIENT_ID_HERE",
                        ClientSecret = "PUT_CLIENT_SECRET_HERE"
                    },
                    Scopes = new[] { DriveService.Scope.Drive },
                    DataStore = new FileDataStore("Drive.Api.Auth.Store")
                });

        public override string GetUserId(Controller controller)
        {
            // In this sample we use the session to store the user identifiers.
            // That's not the best practice, because you should have a logic to identify
            // a user. You might want to use "OpenID Connect".
            // You can read more about the protocol in the following link:
            // https://developers.google.com/accounts/docs/OAuth2Login.
            var user = controller.Session["user"];
            if (user == null)
            {
                user = Guid.NewGuid();
                controller.Session["user"] = user;
            }
            return user.ToString();

        }

        public override IAuthorizationCodeFlow Flow
        {
            get { return flow; }
        }
    }
}

Note about azure you may have to change the location where filedatastore stores the credentials it depends upon where you have write access to. That can be done by supplying a path to the folder you want to store it in.

new FileDataStore(@"c:\datastore",true)