[StarCluster] How does StarCluster track the clusters it's managing?

[Rajat Banerjee]

Sorry for the super-slow response.

The elastic load balancer parses the output of 'qhost' on the cluster:

https://github.com/jtriley/StarCluster/blob/develop/starcluster/balancers/sge/__init__.py#L59

I don't remember the exact reason for using that instead of the same logic
as 'listclusters' above, but here's my guess a few years after the fact:
- Avoids another remote API call to AWS' tagging service to retrieve the
tags for all instances within an account. This needs to be called every
minute, so a speedy call to your cluster instead of to a remote API is
beneficial
- qhost outputs the number of machines correctly configured and able to
process work. If a machine shows up in 'listcluster' but not in 'qhost'
it's likely not usable to process jobs, and would probably need manual
cleanup.

HTH
Raj

On Tue, Mar 10, 2015 at 4:04 PM, Steve Darnell <darnells at dnastar.com> wrote:

>  On a related topic, does anyone know how the load balancing feature
> tracks the cluster and its compute nodes? I have gotten into situations
> where listclusters correctly reports that a cluster and its nodes are
> running (I can ssh into master and the nodes, etc.); however, loadbalance
> reports that the cluster is not running and refuses to balance the cluster.
>
>
>
> Best regards,
>
> Steve
>
>
>
> *From:* starcluster-bounces at mit.edu [mailto:starcluster-bounces at mit.edu] *On
> Behalf Of *Eduardo Gurgel Valente
> *Sent:* Tuesday, March 10, 2015 2:08 PM
> *To:* Nicholas Chammas
> *Cc:* starcluster at mit.edu
> *Subject:* Re: [StarCluster] How does StarCluster track the clusters it's
> managing?
>
>
>
> Hi Nick,
>
>    Look at the security group it creates.  It follows a naming
> convention.  In addition there are tags with encrypted information at play.
>
> Eduardo
>
>
>
> On Mon, Mar 9, 2015 at 11:16 PM, Nicholas Chammas <
> nicholas.chammas at gmail.com> wrote:
>
> Howdy!
>
> At this point in the StarCluster demo video
> <http://youtu.be/vC3lJcPq1FY?t=7m20s>, the presenter runs the following
> command to list all the clusters being managed by StarCluster:
>
> starcluster listclusters
>
> How does StarCluster track all the clusters it’s managing? Is it through
> the use of EC2 instance tags? A pointer to the relevant code would also be
> helpful.
>
> I’m looking to implement a feature similar to listclusters but for
> spark-ec2 <http://spark.apache.org/docs/1.2.1/ec2-scripts.html>. Tagging
> seems like the way to go to do that, but we had some issues with it
> <https://issues.apache.org/jira/browse/SPARK-3332> when we used it with
> spark-ec2.
>
> So I’m curious to know how StarCluster did things.
>
> Nick
>
> ​
>
>
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