Cannot acces Asp.Net Core on local Docker Container

Question

I've created a app in asp.net core and create a dockerfile to generate a local image and run it.

FROM microsoft/dotnet:latest

COPY . /app

WORKDIR /app

RUN ["dotnet", "restore"]

RUN ["dotnet", "build"]

EXPOSE 5000/tcp

ENTRYPOINT ["dotnet", "run", "--server.urls", "http://0.0.0.0:5000"]

Then, I've builded my image with the following command

docker build -t jedidocker/first .

Then, I've created a container with the following command

docker run -t -d -p 5000:5000 jedidocker/first

But when I run the following url into my host browser

http://localhost:5000/

I have an ERR_EMPTY_RESPONSE

is it a network problem? How can I solve it?

P.S: My windows version is 10.0.10586

Answer 1

I had the same issue and found the solution to this. You will need to change the default listening hostname. By default, the app will listen to the localhost, ignoring any incoming requests from outside the container. Change your code in program.cs to listen for all incoming calls:

public class Program
{
    public static void Main(string[] args)
    {
        var host = new WebHostBuilder()
            .UseKestrel()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseUrls("http://*:5000")
            .UseIISIntegration()
            .UseStartup<Startup>()
            .Build();

        host.Run();
    }
}

More info:

https://medium.com/trafi-tech-beat/running-net-core-on-docker-c438889eb5a#.hwhoak2c0

Make sure you are running the container with the -p flag with the port binding.

docker run -p 5000:5000 <containerid>

At the time of this writing, it seems that the

EXPOSE 5000:5000

command does not have the same effect as the -p command. I haven't had real success with -P (upper case) either.

Edit 8/28/2016:

One thing to note. If you are using docker compose with the -d (detached) mode, it may take a little while for the dotnet run command to launch the server. Until it's done executing the command (and any other before it), you will receive ERR_EMPTY_RESPONSE in Chrome.

Answer 2

Just update your entry point as follows, no code change is required:

ENTRYPOINT ["dotnet", "run", "--server.urls", "http://*:5000"]

The default Docker network on Windows Server 2016 is NAT, so you may want to use the IP which you can find out with docker inspect <container name/ID>. Not sure if this is the case with other Windows versions as well.

Answer 3

Here's what worked for me in ASP.NET 3.1

On the Dockerfile You need to specify the ENV ASPNETCORE_URLS

ENV ASPNETCORE_URLS http://*:5000

then EXPOSE the PORT

EXPOSE 5000