Better dual-stack support

[jaymzh]

Is your feature request related to a problem? Please describe.

It's not possible to listen on both v4 and v6 of localhost. Unlike :: which is a somewhat-magical setting that enables both families in Linux (and all addresses), for anything else (like localhost), there's no good solution.

You can set bind to 127.0.0.1 or to ::1, but you can't set it to both addresses, or to just localhost.

Describe the solution you'd like

• When specifying a hostname like localhost, all relevant addresses are listend/bound. For example:

irb(main):016:0> Addrinfo.getaddrinfo('localhost', 5140).select { |x| x.socktype == Socket::SOCK_DGRAM }           
=> [#<Addrinfo: [::1]:5140 UDP (localhost)>, #<Addrinfo: 127.0.0.1:5140 UDP (localhost)>]

Describe alternatives you've considered

An alternative might be multiple bind statements, but... that's suboptimal.

[github-actions]

This issue has been automatically marked as stale because it has been open 90 days with no activity. Remove stale label or comment or this issue will be closed in 30 days

[jaymzh]

@ganmacs can you remove the stale label please, this is still broken - fluent still can't handle dual-stack environments.

[ashie]

It's a duplicated issue of #3001, and #3001 has more information including a workaround solution.
Should be merged to #3001.