[one-ecosystem] help for source code

[Simon Boulet]

Hi,

On Tue, Apr 24, 2012 at 10:05 AM, Carlos Martín Sánchez
<cmartin at opennebula.org> wrote:

>
> As I said, the scheduler is a separate executable from oned (the core). It
> basically queries periodically oned for the list of pending VMs, the
> available hosts, and then for each VM filters the Hosts that match the VM
> requirements: the user has ACL permissions to have his VMs deployed in the
> host, the CPU and MEMORY constraints are met, REQUIREMENTS fit, etc. This
> list of Hosts is then sorted using the defined RANK. Finally, the scheduler
> performs the one.vm.deploy calls
>

Is there any plans to make the scheduler more customizable ie. have a
way for users to hook into the scheduling process and influence the VM
placement? OpenNebula is very flexible and easy to hack thanks to the
different modules implementation. However I have yet to find a way to
easily customize the scheduler.

Here are some of the few things I have in mind:

- Implement scheduler wake up for immediate placement / trigger the
scheduler upon VM creation. I was thinking of adding a SIGHUP signal
handler into the scheduler, and then adding the following HOOK into
oned.conf:

VM_HOOK = [
   name      = "trigger_scheduler",
   on        = "CREATE",
   command   = "/usr/bin/killall -HUP mm_sched",
   arguments = "$VMID" ]

- Implement PRE_SCHED and POST_SCHED environment variables (or
something alike). The idea would be to influence the lists of
available hosts. For example:

1- The PRE_SCHED script receives in STDIN the full lists of hosts that
are online, filter out any unwanted hosts, and output a new list in
STDOUT.
2- The scheduler would do normal scheduling policy from the list
received from PRE_SCHED
3- The POST_SCHED receives in STDIN the list of hosts sorted in
descending order by the scheduler, filter out any unwanted hosts, and
output  the host to be deployed on in STDOUT.
4- The scheduler calls one.vm.deploy with the host received from POST_SCHED.

What are your thoughts?

Simon