Question on DNS Resolving, Multiple Virtual Hosts, Virtualization and DHCP

Question

Preface:

• there are several virtual machine instances (one of KVM/XEN/OpenVZ/VirtualBox)
• each virtual machine instance can hold several virtual hosts (e.g. static.machine0, streaming.vmachine0, static.vmachine1, streaming.vmachine1, static.vmachine2, ...)
• IP's are assigned via DHCP for easy to use
• there is a network of several physical servers with VT-X hardware support, which serve as hosts to virtual machine instances. IP's are assigned via DHCP for easy to use

Solution needs to:

• use Internet withing VM instances
• both physical servers and VM instances within local network can access VM instance via it's hostname
• SSH access within VM instances
• ability to clone VM instances and reconfigure host settings.

Possible keywords: DNS Resolving, Multiple Virtual Hosts, Virtualization, DHCP, UNIX/Linux, Linux, System Administration

Please give me a clue or possible ways of solving this problem and applicable technologies. Thank you.

Answer 1

I didn't understand very well what the 'problem' is, but for the DNS problem you can configure Dynamic DNS, so each machine will be automatically registered on DNS when it gets an IP address from the DHCP. You of course need a DNS/DHCP server that supports it (named/BIND and dhcpd from linux can do it). Here is a good tutorial about DDNS.

As for virtualization, I like Xen and Ganeti to provide management and migration/failover operations.

Answer 2

It is generally a good idea to provide fixed IP addresses for your servers (i.e. predefined IP addresses handed out by the DHCP server), as this will allow you to also used static DNS records (and believe, I speak from experience, dynamic DNS can be done, but you don't want to do it). So:

1. define an IP address map for all your hosts and guests, record the MAC addresses and configure your DHCP server.
2. define DNS entries for all servers and services that need to be reachable via DNS names.
3. make sure all of these addresses are on the same subnet (or subnets with routing between them) and start all the hosts and virtual machines.

Your normal routing should work from there on, and all your requirements will be fulfilled. The choice of VM platform is entirely yours. Any decent VM software will do this for you.