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c#tfsazure-devops-rest-apiazure-devops-server-2019azure-devops-server

Using TFS Rest API works from curl but not from client dotnet library

I'm using the following code from the library Microsoft.VisualStudio.Services.Client:

var credential = new VssBasicCredential("", "<PAT>");
var url = "<url>"";
using var vssConnection = new VssConnection(new Uri(url), credential);
await vssConnection.ConnectAsync();

It fails with the following exception, which I assume has to do with server not allowing basic auth:

System.ComponentModel.Win32Exception (0x80090020): GSSAPI operation failed with error - Unspecified GSS failure.  Minor code may provide more information (SPNEGO cannot find mechanisms to negotiate).
   at System.Net.NTAuthentication.GetOutgoingBlob(Byte[] incomingBlob, Boolean throwOnError, SecurityStatusPal& statusCode)
   at System.Net.NTAuthentication.GetOutgoingBlob(String incomingBlob)
   at System.Net.Http.AuthenticationHelper.SendWithNtAuthAsync(HttpRequestMessage request, Uri authUri, ICredentials credentials, Boolean isProxyAuth, HttpConnection connection, HttpConnectionPool connectionPool, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.SendWithNtConnectionAuthAsync(HttpConnection connection, HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.AuthenticationHelper.SendWithAuthAsync(HttpRequestMessage request, Uri authUri, ICredentials credentials, Boolean preAuthenticate, Boolean isProxyAuth, Boolean doRequestAuth, HttpConnectionPool pool, CancellationToken cancellationToken)
   at System.Net.Http.DecompressionHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.DiagnosticsHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.Services.Common.VssHttpMessageHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.Services.Common.VssHttpRetryMessageHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task`1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)
   at Microsoft.VisualStudio.Services.WebApi.VssHttpClientBase.SendAsync(HttpRequestMessage message, HttpCompletionOption completionOption, Object userState, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.Services.WebApi.VssHttpClientBase.SendAsync[T](HttpRequestMessage message, Object userState, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.Services.Location.Client.LocationHttpClient.GetConnectionDataAsync(ConnectOptions connectOptions, Int64 lastChangeId, CancellationToken cancellationToken, Object userState)
   at Microsoft.VisualStudio.Services.WebApi.Location.VssServerDataProvider.GetConnectionDataAsync(ConnectOptions connectOptions, Int32 lastChangeId, CancellationToken cancellationToken)
   at Microsoft.VisualStudio.Services.WebApi.Location.VssServerDataProvider.ConnectAsync(ConnectOptions connectOptions, CancellationToken cancellationToken)

However, I manage to execute REST command successfully from command line

curl <url>/_apis/projects -u :<PAT>

I'm using Azure Devops Server 2019 for which I cannot modify any configurations. I'm running the code from dotnet-core Alpine docker image.

Is it a limitation of the dotnet library or am I using it wrong?

Solution

  • The issue was with the Alpine distribution of dotnet Docker image, it does not yet support gss-ntlmssp. Switching to the standard image (Ubuntu based - mcr.microsoft.com/dotnet/core/aspnet:3.1) solved the issue.