Fly dislikes .local domains.

[vectorstorm]

Bug Report

Fly appears to not understand how to use Bonjour-style domains, and generates error messages when attempting to use a concourse install that's running on a .local domain.

Steps to Reproduce

1. Install a binary copy of Concourse on a computer on your local network which advertises a bonjour domain. (In these steps, I'm assuming that it's advertising the name "host.local". Replace that with whatever the machine is actually advertising)
2. Start the server using the command-line parameter: --external-url http://host.local:8080/
3. Verify that the server is running and accessible via web browser at http://host.local:8080/
4. Issue the command: fly -t anything login --concourse-url http://host.local:8080/

Expected Results

Fly should give you a URL to use to login to the website, to authenticate the fly session.

Actual Results

Fly provides the following message:

logging in to team 'main'

could not reach the Concourse server called anything:

Get http://host.local:8080/api/v1/info: dial tcp: lookup host.local on 127.0.0.53:53: server misbehaving

is the targeted Concourse running? better go catch it lol

Additional Context

Worth noting that this only happens with .local domains; if I instead configure the machine with an explicit IP address and point fly at that IP address, then everything works correctly.

Version Info

This is tested on Concourse 4.2.1, binary deployment on a local Ubuntu 18.04 machine. While I've been using Concourse since before version 1.0, I've never tried this configuration before; I've only previously used Concourse with real domain names.