cloudstack-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Chiradeep Vittal <Chiradeep.Vit...@citrix.com>
Subject Re: CloudStack Allocator Pre-Condition Check
Date Mon, 13 Aug 2012 05:03:56 GMT
+ Developer list since it seems to better belong there.

But it seems to me that the allocator is entirely the wrong place to put
such a check. What you are trying to implement is a network check. If you
implement a NetworkElement then your network element gets called whenever
a VM is about to be placed into a network. You can prevent it there.
I don't see what this has to do with the specific host it is placed on.

Chiradeep

On 8/8/12 3:16 PM, "Prachi Damle" <Prachi.Damle@citrix.com> wrote:

>Yeah, if your precondition fails you don't need to call
>super.allocateTo() at all, simply return empty list. You can refer
>FirstFitRoutingAllocator that does the exact same thing.
>
>-Prachi 
>
>-----Original Message-----
>From: Amir Nashat [mailto:Amir.Nashat@citrix.com]
>Sent: Wednesday, August 08, 2012 3:07 PM
>To: 'cloudstack-users@incubator.apache.org'
>Subject: RE: CloudStack Allocator Pre-Condition Check
>
>Ok, I'll use your suggestion of returning an empty list which is what my
>intention was with setting the returnUpTo value to 0. I won't modify the
>returnUpTo value but rather return an empty ArrayList if my pre-condition
>fails. 
>
>It seems my approach was wrong so it's no longer important but to answer
>your question of how I was planning on setting returnUpT=0, I was going
>to extend the FirstFitAllocator class, override the allocateTo() method
>and if my pre-condition failed I would set a value of  returnUpTo = 0 and
>call the super.allocateTo() passing in the modified returnUpTo.
>
>Thanks again for your help!
>
>Amir
>
>
>
>-----Original Message-----
>From: Prachi Damle [mailto:Prachi.Damle@citrix.com]
>Sent: Wednesday, August 08, 2012 2:36 PM
>To: cloudstack-users@incubator.apache.org
>Subject: RE: CloudStack Allocator Pre-Condition Check
>
>Yes you can use vmProfile.getHostName().
>
>About the returnUpTo Value, I don't see why you should set it 0.
>returnUpTo = 1 means you allocator should atmost  1 suitable host - it
>could still return empty result.
>returnUpTo = -1 would mean lalloctaor should return as many matching
>hosts as it finds.
>
>If your pre-condition is not satisfied by the VM profile, you can just
>return an empty list irrespective of the returnUpto value.
>
>Also where do you plan to set the returnUpto value ? The existing
>FirstFitPlanner sets the returnUpTo = -1 and calls the allocators.
>Are you planning on implementing custom planner and set a different
>returnUpto value?
>
>-Prachi
>
>-----Original Message-----
>From: Amir Nashat [mailto:Amir.Nashat@citrix.com]
>Sent: Wednesday, August 08, 2012 2:16 PM
>To: 'cloudstack-users@incubator.apache.org'
>Subject: RE: CloudStack Allocator Pre-Condition Check
>
>Hi Prachi,
>
>So are you suggesting to set the returnUpTo value to 0?
>
>To confirm, I can get the hostname of the guest VM from
>vmProfile.getHostName() ...this is correct?
>
>Thanks for your feedback!
>
>Amir
>
>
>
>-----Original Message-----
>From: Prachi Damle [mailto:Prachi.Damle@citrix.com]
>Sent: Wednesday, August 08, 2012 2:12 PM
>To: cloudstack-users@incubator.apache.org
>Subject: RE: CloudStack Allocator Pre-Condition Check
>
> Amir,
>
>Yes to add any custom checks on top of the existing host allocation you
>will need to write your HostAllocator extending the default
>FirstFitAllocator. Also replace the FirstFitAllocator in componets.xml by
>your custom allocator.
>If your condition verification fails, your allocator should return an
>empty list of hosts and not an error. The deployment planner will handle
>the empty result returned by the host allocator.
>
>Thanks,
>Prachi
>
>
>-----Original Message-----
>From: Amir Nashat [mailto:Amir.Nashat@citrix.com]
>Sent: Wednesday, August 08, 2012 1:58 PM
>To: cloudstack-users@incubator.apache.org
>Subject: CloudStack Allocator Pre-Condition Check
>
>Hello,
>
>I would like to get feedback as to the best approach for performing a
>pre-condition check before allocating a guest vm to a physical host. For
>my example, a pre-condition check is to verify the guest vm does not use
>an existing DNS entry. If the pre-condition fails we do not want to
>allocate the guest vm to the physical host and we want to record this as
>an error condition.
>
>As far as I can tell the only option I have is to extend the default
>FirstFitAllocator class and override the allocateTo methods to first
>perform my pre-condition verification and if it passes then to call the
>the overridden allocateTo() method. If it fails then I would throw a
>RuntimeException of some sort or possibly set the returnUpTo value equal
>to 0.
>
>Can you please advise as what would be the best approach? If anyone else
>is performing pre-conditions checks in their allocation logic before
>provisioning a guest VM please let me know of your approach.
>
>
>Thank you,
>
>Amir


Mime
View raw message