How to open TCP port on localhost on VSTS build agent?

Question

When using the online hosted version of Visual Studio Team Services, my unit tests are unable to connect to a service listening on a TCP port on the localhost of the build agent. The service is able to start and open the TCP port but it seems unreachable for the unit test.

Error message:

2017-06-20T12:05:00.8231306Z ##[error]------------ System.Net.Http.HttpRequestException : An error occurred while sending the request. 2017-06-20T12:05:00.8231306Z ##[error]---------------- System.Net.WebException : Unable to connect to the remote server 2017-06-20T12:05:00.8231306Z ##[error]-------------------- System.Net.Sockets.SocketException : No connection could be made because the target machine actively refused it 127.0.0.1:41670

The service that opens the TCP port is started with:

    public void Start()
    {
        HttpPort = ObtainFreePort();
        TcpPort = ObtainFreePort();
        ClusterVNode node = EmbeddedVNodeBuilder.AsSingleNode()
            .WithInternalTcpOn(new IPEndPoint(IPAddress.Loopback, TcpPort))
            .WithExternalTcpOn(new IPEndPoint(IPAddress.Loopback, TcpPort))
            .WithInternalHttpOn(new IPEndPoint(IPAddress.Loopback, HttpPort))
            .WithExternalHttpOn(new IPEndPoint(IPAddress.Loopback, HttpPort))
            .AddExternalHttpPrefix($"http://+:{HttpPort}/")
            .RunProjections(ProjectionsMode.All)
            .StartStandardProjections()
            .RunInMemory()
            .Build();
        node.StartAndWaitUntilReady().Wait();
    }

    static int ObtainFreePort()
    {
        using (var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
        {
            sock.Bind(new IPEndPoint(IPAddress.Loopback, 0));
            var port = ((IPEndPoint)sock.LocalEndPoint).Port;
            sock.Close();
            return port;
        }
    }

This does work on my local machine :) Is this not supported in Visual Studio Team Services online?

score 3 · Accepted Answer · answered Jun 20 '17 at 20:46

3

If you're using the hosted agent, you can't open up ports or change anything about the machine's configuration. You'll need to set up your own agent for builds.

Also, if a test requires TCP communication, it's no longer a unit test. Unit tests have no external dependencies.

answered Jun 20 '17 at 20:46

Daniel Mann

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Yeah we call these tests integration tests to be exact. Too bad this isn't possible and we have to set up our own agents.. But thanks for the answer! – Alexander van Trijffel Jun 21 '17 at 21:42

How to open TCP port on localhost on VSTS build agent?

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