switch to minimal hostname

static/backplane-dns-client/dns-client.rb

@@ -224,8 +224,12 @@ def host_sshfp
   keys.compact
 end
 
+def hostname
+  Socket.gethostname.split(".").first
+end
+
 client = XMPPClient::new(options[:domain],
-                         Socket::gethostname,
+                         hostname,
                          options[:server],
                          password)
 
@@ -243,7 +247,7 @@ begin
   if options[:ipv4]
     ipv4 = addrs.find { |ip| ip.ipv4? }
     if ipv4
-      puts "#{options[:server]}: #{Socket::gethostname}.#{options[:domain]} IN A => #{ipv4.to_s}"
+      puts "#{options[:server]}: #{hostname}.#{options[:domain]} IN A => #{ipv4.to_s}"
       if client.send_ip(ipv4)
         puts "OK"
       else
@@ -258,7 +262,7 @@ begin
   if options[:ipv6]
     ipv6 = addrs.find { |ip| ip.ipv6? }
     if ipv6
-      puts "#{options[:server]}: #{Socket::gethostname}.#{options[:domain]} IN AAAA => #{ipv6.to_s}"
+      puts "#{options[:server]}: #{hostname}.#{options[:domain]} IN AAAA => #{ipv6.to_s}"
       if client.send_ip(ipv6)
         puts "OK"
       else
@@ -273,7 +277,7 @@ begin
   if options[:sshfp]
     fps = host_sshfp
     if not fps.empty?
-      puts "#{options[:server]}: #{Socket::gethostname}.#{options[:domain]} IN SSHFP => #{fps}"
+      puts "#{options[:server]}: #{hostname}.#{options[:domain]} IN SSHFP => #{fps}"
       if client.send_sshfp(fps)
         puts "OK"
       else