Accept Docker service hostnames in addition to IP addresses in configuration.

[XAMPPRocky]

Currently if you use a docker hostname in the configuration you'll get an error about a invalid IP address, but there are times where you need to get IP from the hostname. When I was trying to make a docker-compose version of the iperf3 for #410, docker compose gives services hostnames for service discovery, but these are not picked up by std's implementation of ToSocketAddrs or dns-lookup it seems.

[iffyio]

Is this ticket more to be able to accept dns names or is the issue docker-compose specific?
Re the docker scenario, I imagine docker's using dns names that are by default only valid within the bridge network it runs the containers so unless quilkin is part of that network it won't be able to resolve them. And we'd need to e.g run quilkin in the same network, somehow make docker's private dns resolvable on the host machine (it sounds like its not currently) or pass the ip address that those entries point to in quilkin's config

[iffyio]

Removed the bug label since we explicitly call out that only ip address and port is supported in both static and dynamic configs

[XAMPPRocky]

Is this ticket more to be able to accept dns names or is the issue docker-compose specific?

It's specific to docker networks (not just compose), as I believe the DNS works the same.

And we'd need to e.g run quilkin in the same network, somehow make docker's private dns resolvable on the host machine (it sounds like its not currently) or pass the ip address that those entries point to in quilkin's config

I mean I think I am running in the network with compose, I'm honestly surprised it doesn't just work. I thought it was supposed to be transparent to processes running in the container. I'm testing with this code.

Dockerfile

FROM rust:latest
WORKDIR /app
RUN cargo init --name dns-test .
RUN echo 'dns-lookup = "*"' >> Cargo.toml
COPY main.rs /app/src/main.rs
RUN cargo build
CMD ["cargo", "run"]

main.rs

fn main() {
    println!("{:?}", dns_lookup::lookup_host("iperf:8000").unwrap());
}

compose.yml

  dns_test:
    build: .
  iperf:
    image: networkstatic/iperf3:latest
    restart: always
    ports:
      - 8000:5201
    command: -s

[iffyio]

so it seems dns only works out of the box from compose version 2 and above, I tried with the following that worked

version: '2'
services:
  dns_test:
    build: .
  iperf:
    image: networkstatic/iperf3:latest
    restart: always
    ports:
      - 8000:5201
    command: -s

fn main() {
        println!("it were: {:?}", dns_lookup::lookup_host("iperf").unwrap());
}

[XAMPPRocky]

Ah the issue is with having the :<port>. Very odd, but oh well.

[XAMPPRocky]

Actually I'm going to re-open because we need to be able to set the port in quilkin endpoint configuration, and I don't know how to do that without changing the serde impl, because it seems like we need to parse the host and port separately due to ToSocketAddrs not performing a full lookup. So we have to query the DNS, because the following still fails.

fn main() {
        println!("it were: {:?}", "iperf".parse::<std::net::SocketAddr>().unwrap());
}