Why is are my published ports not working?

Question

I've created a docker image containing a rust application that responds to get requests on port 8000. The application itself is a basic example using the rocket library (https://rocket.rs/) it looks like this

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use] extern crate rocket;

#[get("/")]
fn index() -> &'static str {
    "Hello, world!"
}

fn main() {
    rocket::ignite().mount("/", routes![index]).launch();
}

I have compiled this and called it server

I then created a Docker file to host it

FROM ubuntu:16.04

RUN apt-get update; apt-get install -y curl

COPY server /root/

EXPOSE 8000

CMD ["/root/server"]

I build the docker image with $ docker build -t port_test and run it with $ docker run -p 8000:8000 port_test

At this point it all looks good

$ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED                     STATUS              PORTS                    NAMES
3befe0c272f7        port_test           "/root/server"      7 minutes ago       Up 7 minutes        0.0.0.0:8000->8000/tcp   festive_wilson

If I run curl within the container it works fine

$ docker exec -it 3befe0c272f7 curl -s localhost:8000
Hello, world!

However I can't do the same from the host

$ curl localhost:8000
curl: (56) Recv failure: Connection reset by peer

That sounds like the symptom of the server process binding to 127.0.0.1 and being unreachable from outside the container, with the answer being to bind to 0.0.0.0, but I can't tell you how to address it for this particular server stack. — David Maze, Jan 09 '19 at 23:07
That was the issue. If you make this an answer I will accept it. — rvabdn, Jan 10 '19 at 00:19

score 9 · Answer 1 · answered Jan 10 '19 at 22:30

9

David Maze was correct. The problem was that the process was binding to localhost in the container. I added a Rocket.toml file with the following entries

[global]
address = "0.0.0.0"

[development]
address = "0.0.0.0"

and now it works fine.

Thanks David.

answered Jan 10 '19 at 22:30

rvabdn

947
6
20

the profile `development` is deprecated. Use `debug` instead. – rherrmannr Jul 02 '23 at 09:20

score 3 · Answer 2 · answered Jan 10 '19 at 00:03

3

Rocket have different standard configuration, please try staging or prod to be able to do what you want, source.

ROCKET_ENV=staging cargo run

Why is are my published ports not working?

2 Answers2

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