Rust TCP Server in Docker Container Not Working - docker

Question

I'm struggling to understand why the tcp server can't accept outside requests.
My Server:
use std::io::Write;
use std::net::TcpListener;
use std::thread;
fn main() {
let listener = TcpListener::bind("0.0.0.0:8080").unwrap();
println!("listening started, ready to accept");
for stream in listener.incoming() {
thread::spawn(|| {
let mut stream = stream.unwrap();
stream.write(b"Hello World\r\n").unwrap();
});
}
}
Docker File
FROM rust:1.31
WORKDIR /usr/src/proto-rust
COPY . .
RUN cargo install --path .
EXPOSE 8080
CMD ["cargo", "run"]
Running Locally, this works
nc 0.0.0.0 8080
After running the following:
docker run --rm -p 8080:8080 --name my-running-app proto-rust
and checking the docker bridge
docker network inspect bridge
[
{
"Name": "bridge",
"Id": "78d335687fcd96ad1051ca17662024708dff9db4d3043b787a43d29edbb8ff58",
"Created": "2022-09-03T01:53:48.606052848Z",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "172.17.0.0/16",
"Gateway": "172.17.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"21a4f5fec2cb2a880ed01c044ccaf001e120c9b507d34fabf93c9da21957d558": {
"Name": "my-running-app",
"EndpointID": "34a003ea12612d479e47a61478f3a445455f919a66350b9b5fde651e6cb8a12b",
"MacAddress": "02:42:ac:11:00:02",
"IPv4Address": "172.17.0.2/16",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.bridge.default_bridge": "true",
"com.docker.network.bridge.enable_icc": "true",
"com.docker.network.bridge.enable_ip_masquerade": "true",
"com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
"com.docker.network.bridge.name": "docker0",
"com.docker.network.driver.mtu": "1500"
},
"Labels": {}
}
]
Running either of the following does not work:
nc 172.17.0.2 8080
nc localhost 8080
I'm not sure where to go from here. I think my ip address for the docker container is wrong because netcat can't see the open port? I'm not sure here. Why do I even need the extra address as well as the network bridge? It's wild docker can't just expose on localhost.

Answer 1

I had originally made the server 127.0.0.1, and then changed it to 0.0.0.0 after since docker only binds on localhost. However, I did not run docker build, which meant the update never applied to the docker image. After running
docker build -t proto-rust .
the following works:
nc localhost 8080