Generate ISO from installed system

Question

As part of my infrastructure I have many Virtual Machines running different Linux distros, under Proxmox using OpenVz. My problem is that I need to export into a personalized installable ISOs some of the VMs I have, (installable snapshots of the current state of the VMs), some of them are running Ubuntu, some of them CentOS, so my question is: 1- Is there a way I can do this aware of the OS the VM is running?, 2- Exporting VMs to ISOs the way I just explained is the way to go or is there any other approach? I'm open to any advice from those how has experience with this subject even if I have to setup different Virt. Technology to host the VMs.

Answer 1

Your question is pretty vague on your requirements. I'll try to give you some ideas:

What do you mean by "Current state"? If you really want all the running processes, then you should something like VirtualBox and take a snapshot. You can easily boot that up on another computer and continue running where you left off, and it's independent of the OS.

If you really mean just the filesystem, then just copying the filesystem and burning it on a CD is unlikely to give you good results. For instance, there are many areas that are expected to be writable (/var, /tmp. even /etc for /etc/resolv.conf)

One simple idea is to just 'tar' up the filesystem, and untar it on another OpenVz distro. (I'm sure someone has made a bootable OpenVz distro..)

If you want a real bootable ISO, there are a LOT of different options. For example, you could have the kernel mount the ISO as root. Or you could boot to a RAMDisk as root, and unpack the filesystem you need. Or you could mount the ISO as root with an AUFS overlay filesystem. Or you could mount some directories as a SquashFS filesystem onto a RAM root.

But if you really want simplicity in "moving VMs around", look into Docker. It has a simple way to push a filesystem up to a public or private server, then download it on the other side, but save bandwidth on common elements like the OS and Apache installs. (If you do it right.)