Docker: cannot get access to server

Question

Here is a little of backstory. I implemented a couple of web APIs using microservices architecture. I am trying to make my microservices accessible via HTTPS. The microservices are developed using .net core, so according to Microsoft document, to enforce HTTPS, I need to configure Kestrel. Following is how I did it.

.UseKestrel(options =>
            {
                options.Listen(IPAddress.Loopback, 5000);
                options.Listen(IPAddress.Loopback, 5001, listenOptions =>
                {
                    listenOptions.UseHttps("cert.pfx", "pwd");
                });
            }) 

To make it simple, I use kestrel by itself and skip reverse proxy. I will certainly include Nginx as reverse proxy but that is the future work. I tested locally, it worked. Then, I deployed it onto Docker. Here is the docker-compose.override file

version: '3.4'

services:
dataservice:
  environment:
    - ASPNETCORE_ENVIRONMENT=Development
    - ASPNETCORE_URLS=https://+:443;http://+:80
  ports:
    - "5000:80"
    - "5001:443"

In dockerfile, port 5000 and 5001 are exposed. I built the project into images, and run it on docker, using docker run -it --rm -p 5000:80 --name *name* *imagename*. Docker shows Now listening on: http://127.0.0.1:5000 and Now listening on: https://127.0.0.1:5001. Now the problem is, leave the https part aside, the APIs cannot even accessed by http. The browser just shows This page isn’t working 127.0.0.1 didn’t send any data. ERR_EMPTY_RESPONSE. I found a similar question from here Docker: cannot open port from container to host , somehow this is about server should listen to 0.0.0.0. Though I am not fully understand the reason, I changed the kestrel configuration to

options.Listen(IPAddress.Any, 5000);

built and ran docker images again, and Docker shows Now listening on: http://0.0.0.0:5000, still it doesn't work. I also tried to replace the IP with localhost, it has no use. I did not use .UseHttpsRedirection(), https should have nothing to do with the problem.

Am I missing any configuration or doing anything wrong? It would be really helpful if anyone could shed some light. Thank you in advance.

Answer 1

You should listen on 80 and 443 inside the container, i.e. options.Listen(IPAddress.Any, 80); because this docker declaration

ports: 
   - "5000:80"

means that the local port 80 (the port from your source code) is exported to external port 5000, and not the other way around.