Can't connect to embedded undertow server running inside docker container

Question

I'm trying to run an embedded undertow server inside a docker container. When I run the following code snippet in my machine, I can able to hit the http endpoint which returns "Hello World". But I can't reach the endpoint when I run the same code inside the docker container.

public class HelloWorldServer {

    public static void main(final String[] args) {
        Undertow server = Undertow.builder()
                .addHttpListener(8080, "localhost")
                .setHandler(new HttpHandler() {
                    @Override
                    public void handleRequest(final HttpServerExchange exchange) throws Exception {
                        exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "text/plain");
                        exchange.getResponseSender().send("Hello World");
                    }
                }).build();
        server.start();
    }
}

I found the above example from the following link http://undertow.io/undertow-docs/undertow-docs-1.4.0/index.html

These are all the following commands I execute to build and run the container.

docker build -t z .
docker run -d -p 8080:8080 -t z

Answer 1

The undertow server failed to bind http listener with my machine's IP. instead of specifying

localhost

I changed to

InetAddress.getLocalHost().getHostAddress()

which bind the listener with my machine's IP. Now I can able to hit the endpoint.