January 29, 2012
I setup rhev 3 and eucalyptus 2 last week. I’ll talk about rhev eventually but I have some initial thoughts on euca I want to get down.
1. install instructions are mostly good but need some work to make it clear what ELSE I need to setup
2. the overview docs are good but 10m spent talking to andy grimm cleared up everything A WHOLE LOT MORE.
Now let’s go onto my rant:
First I want to thank Greg Dekoenigsberg for getting the images list at eucalyptus setup. That helped point me in roughly the right direction. It was a big help. But lets be clear I will never use someone else’s image for my own servers. NEVER. Do you know why? B/c I do not trust other people to either a. not be morons or b. do something intentionally crappy. I’m happy the list exists b/c in addition to advertising existing images (which are quite helpful) it also promotes the discussion of how making images is stupidly difficult and under-documented.
So: Why is making images that frelling hard?
To make an image you more or less setup an installroot – blow the pkgs in there then you go screw with them some. Then perform a relatively complicated set of things to make it ‘work’ and then upload it to euca.
This is dumb.
1. installing to an install root is what the INSTALLER is for
2. the installer for rhel/fedora/centos/SL, etc, etc, etc is anaconda
3. the automated installer for these is kickstart
4. for a euca instance you have:
c. disk (sorta)
Last I checked that’s all you need to run anaconda (and kickstart).
I’ve been an admin for a long time now and I’ve been mass installing systems since LONG before many people understood why that was important. I’ve been using kickstart (practically the same basic kickstart) for about 12 yrs now. Why would I want a NEW tool for installing instances and setting up images? Especially a new, inferior, incompatible tool with a format that means I have to go screw with how I’ve been installing systems for OVER A DECADE? I would not. There is no reason. There is nothing that makes that make sense.
The anaconda developers have done a STELLAR job maintaining compatibility with the kickstart format to the point that the whole linux-using world has realized it. To the point that I can almost take my ks.cfg from rhl 7.2 and have it work on rhel 6. Even if I’m going to install and instance, take a snapshot and immediately use that as my clone for all new instances – it is still easier and better if the mechanism I use is the same as I would use on any other server. If only for consistency.
(The first person who says something about consistency and hobgoblins of little minds will:
a. get slapped and b. get reminded that the first line is a ‘foolish consistency’)
Moreover doing things from kickstart as the basis for the images means:
1. you’re not inheriting bizarre little things you forgot you modified in your image
2. you’re starting from known good (and gpg-verifiable) pkgs
3. you don’t need to change your established practices.
Let’s say, in an ideal world, all my instances are in my private cloud running on euca. That’s great, but the cloud controller and nodes that run euca aren’t able to use those images, – so I’m going to have to install (and reinstall) those. Which means I’m going to be using kickstart. So, yah any install tool must use kickstart at its base.
So, with that in mind I had lunch with Greg and Andy on Friday and we discussed this a good bit. Then after Andy and I talked about the problem space some he explained what the limiting factor was. He then mentioned someone working on Neuca at Renci and the patches they have to do something related (as in to modify the xml that is passed to libvirt to generate images) and after he mentioned his first name and that he was at duke I realized that he lives 2 blocks away from me and I’ve known him for over a decade. :) So I called him and we talked about whether or not the patches to neuca will do what I want (which is to let you kickstart to install an image). It’s not in the bag yet but it sure seems like the bag is open and all the pieces appear to be able to fit inside.
After talking with Victor friday evening I felt a good deal better. I couldn’t imagine why this hasn’t already been addressed therefore I thought I was missing something obvious, something that made this trivial and I just ignored it. No, in fact, I hadn’t missed anything – building images is stupidly difficult and obtuse and for no good reason.
There’s a lot more to go but I’m looking forward to tinkering with this when I get back from a little trip on wednesday.