无法从Docker访问Golang Web服务器

Question

I am using the Gorilla framework in Go to expose a webservice. I have a "Hello World" endpoint at /hello which works fine when hit from Postman, browser or curl.

The problem arises when I bundle it with Docker. My Dockerfile is as below

FROM alpine
COPY ./target/himer-users-go /app
ENV PORT 9000
RUN echo $PORT
ENTRYPOINT /app
EXPOSE ${PORT}

Now I can ssh into the container and ping the server using wget (since alpine doesn't come bundled with curl)

But when I run the image like

docker run -d -p 9000:9000 namespace/image

I can't access the server in any way from my host system.

Any help would be greatly appreciated.

Answer 1

I solved it by exposing the server at 0.0.0.0 instead of localhost

The problem is that I've told my webserver to only serve requests sent to localhost. Because of the network mangling that Docker does, none of the traffic showing up to your webserver look to the webserver as though they were sent to localhost. By telling the webserver to listen on 0.0.0.0, I'm effectively telling it that it doesn't care where the traffic was originally sent and it will accept it all.