ipv6.rb

require 'net/http'

uri = URI.parse('http://[::1]:3000')

puts uri.host #=> '[::1]'
puts uri.hostname #=> '::1'

Net::HTTP.start(uri.host, uri.port) do |http|
  http.get('/')
end #=> getaddrinfo: Name or  2 vice not known (SocketError)

Net::HTTP.start(uri.hostname, uri.port) do |http|
  http.get('/')
end #=> #<Net::HTTPOK..