debian-mirror-gitlab/lib/gitlab/database/load_balancing/resolver.rb

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2021-09-04 01:27:46 +05:30
# frozen_string_literal: true
require 'net/dns'
require 'resolv'
module Gitlab
module Database
module LoadBalancing
class Resolver
UnresolvableNameserverError = Class.new(StandardError)
def initialize(nameserver)
@nameserver = nameserver
end
def resolve
address = ip_address || ip_address_from_hosts_file ||
ip_address_from_dns
unless address
raise UnresolvableNameserverError,
"could not resolve #{@nameserver}"
end
address
end
private
def ip_address
IPAddr.new(@nameserver)
rescue IPAddr::InvalidAddressError
end
def ip_address_from_hosts_file
ip = Resolv::Hosts.new.getaddress(@nameserver)
IPAddr.new(ip)
rescue Resolv::ResolvError
end
def ip_address_from_dns
answer = Net::DNS::Resolver.start(@nameserver, Net::DNS::A).answer
return if answer.empty?
answer.first.address
rescue Net::DNS::Resolver::NoResponseError
raise UnresolvableNameserverError, "no response from DNS server(s)"
end
end
end
end
end