From: Ian Main imain@redhat.com Date: Fri, 11 Mar 2011 16:04:00 -0500
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IP Discovery ------------
There are many possible solutions to this problem but none of them are obviously better than any other. The three that seem the most promising are:
1) Using an agent in the VMs to register with a central server thereby letting us know its IP. 2) Having control of the DHCP server so we can see which leases are out for which MACs. 3) Using a config file which maps MACs to IPs and then configuring dhcpd with the same mapping.
Of these I'm thinking we should implement #3 first.
3 is relatively easy. I would have thought 2 was easy, but I'm told that we can't count on it.
My observation is that, immediately after you prove that you can launch an instance, you're going to need to care about configuring it. That means you need the config server, which is door number 1. So I advocate that we just bite the bullet and do that one right away. I think this should get us up and running quickly and it can be configured in almost any environment. Second option would be #1. I think in the end we will need to implement all of these and have it be configurable by the admin.
You always need 1, regardless of what other things you do.
Other tidbit that I didn't see: We have the ability to inject some small snippet of data at launch time, correct? For instance as a karg or something? I'm pretty sure we talked about this offline, but I want to make sure (a) the answer is yes, and (b) we build it into the api.
This looks great so far. Thanks for writing this up!