[Starcluster] Load balancer is safe(r)

[Justin Riley]

Dan,

> Great.   And, will the ClusterSetup class be extended to have a method "run_incremental_add" (or something with a better name) that's run upon add_node after the default setup ops are called?  (Like plugins 
> are now.)

Yes there will be hooks in ClusterSetup for a plugin to be executed at after/before the add/remove operations.

> Have you guys thought about having a "shutdown" method in the ClusterSetup class, an inverse to the "run" method --  to be run upon call to starcluster stop?   E.g. to handle any user-defined shutdown 
> procedures?  Presumably it would be run prior to calling the default shutdown process (inverse to the "run" method).   And by analogy one could have a "shutdown_incremental_remove" to be run prior to 
> shutdown of an individual node when remove_node is called.

So right now the shutdown procedure for "starcluster stop" is to just terminate all of the instances and remove the cluster's security group and cancel any spot requests. This is a very simple procedure that currently does not require a keypair to execute, only your AWS credentials. I'd like to keep the stop method this way. Having a plugin involved in the "stop" command would require an ssh connection to the cluster. Currently only start, sshmaster, sshnode, and sshinstance strictly require a keypair and I think this makes sense. Having to have an ssh key to shutdown a cluster is odd I think, especially since no keypair is necessary to terminate the instances. Perhaps we could have an optional flag that would kick off a plugin's shutdown hooks and requires the ssh key but this certainly would not be the default behavior.

~Justin


________________________________________
From: starcluster-bounces at MIT.EDU [starcluster-bounces at MIT.EDU] On Behalf Of Dan Yamins [dyamins at gmail.com]
Sent: Wednesday, July 28, 2010 10:59 PM
To: starcluster at mit.edu
Subject: Re: [Starcluster] Load balancer is safe(r)

Great.   And, will the ClusterSetup class be extended to have a method "run_incremental_add" (or something with a better name) that's run upon add_node after the default setup ops are called?  (Like plugins are now.)

Also:  have you guys thought about having a "shutdown" method in the ClusterSetup class, an inverse to the "run" method --  to be run upon call to starcluster stop?   E.g. to handle any user-defined shutdown procedures?  Presumably it would be run prior to calling the default shutdown process (inverse to the "run" method).   And by analogy one could have a "shutdown_incremental_remove" to be run prior to shutdown of an individual node when remove_node is called.

Da


On Wed, Jul 28, 2010 at 10:51 PM, Rajat Banerjee <rqbanerjee at gmail.com<mailto:rqbanerjee at gmail.com>> wrote:
They will definitely be exposed in the shell (you can use them
already), but we can probably expose them on the command line too.
Justin's choice.

Raj


On Wed, Jul 28, 2010 at 10:49 PM, Dan Yamins <dyamins at gmail.com<mailto:dyamins at gmail.com>> wrote:
> When the loadbalancer is released, will the underlying "add_node" and
> "remove_node" (whatever they are actually called) be exposed as part of the
> user-facing api?  That is, in addition to the loadbalancer function built on
> top of these functions?
>
> Dan
>
> On Wed, Jul 28, 2010 at 10:46 PM, Rajat Banerjee <rbanerj at fas.harvard.edu<mailto:rbanerj at fas.harvard.edu>>
> wrote:
>>
>> Hi All,
>> The load balancer has been much improved and several of the bugs I
>> described last time have been fixed. I've just run an elaborate system
>> test on it and haven't seen any issues. I encourage you to try it.
>>
>> It will be formally released in a few weeks after Justin releases the
>> main / stable branch. Until then, it is available through GitHub per
>> the instructions in my last email.
>>
>> The attatched JPG explains the decision making process of the load
>> balancer.
>>
>> <img src="http://www.hindoogle.com/img/starcluster-decision-diagram.jpg">
>>
>> http://www.hindoogle.com/img/starcluster-decision-diagram.jpg
>>
>> Thanks,
>> Rajat
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