[Kimchi-devel] [RFC] Live migration backend + API

[Daniel Henrique Barboza]

Hi,

Live migration will be one of the new features for Kimchi 2.0 and I've 
been investigating it for a week or so. This is how I'm planning to 
implement it:

- API:

The API will be similar to the API of the 'cloneGuest', but with extra 
parameters:

url : 'plugins/kimchi/vms/' +'vm_name' + "/migrate"
type: 'POST'
parameters:
* destination: the IP address of the destination host
* (optional, not sure if applicable) password: the password to log in 
the destination via ssh tunnel

In my opinion we can start with a 'migrate' button in the options of the 
VM, which will open up a new window to insert the destination IP 
address. This of course thinking about the old UI. I believe we can do 
whatever it is done with the 'Clone' function in the case of the new UI, 
with this extra window.

As the migration might take a while, we'll need a progress bar or 
something to demonstrate that the progress is still ongoing. Again, the 
same thing as clone does :)

- backend and core functionality:

This is where it gets tricky. Libvirt has *a lot* of ways to do a live 
migration between hosts. My approach, at least for this first attempt, 
will be focusing in a single way, implement it, stabilize it and then 
extend it to the other migration types, if necessary.

Same thing goes for the preset up. The only way I managed to do a live 
migration was with a NFS storage pool in both hosts, same name and same 
NFS server. This shared storage is necessary because the live migration 
will *not* copy the disks of the VM, just the RAM memory. I had to share 
ssh keys between the hosts to allow for password less ssh sessions.

At first, I want to relieve this first implementation from this pre 
config, which will have to be done entirely by the user. If everything 
goes well, I can add a few automation in this process inside the backend 
before the 2.0 launch.

Kimchi internals will be implemented by using async task facilities.



Any questions? Comments?



Daniel