How to balance aming multiple runner instances

[alvi...@gmail.com]

Hi,

I started from an installation with only one CF runner instance, with 2 app deployed on it.

Then I modified my cf-deployment.yml increasing by one the number of runner instances. I ran "bosh deploy" and now I've correctly running 2 runner instances.

Then I deployed a new App. It went again on the first CF runner instance (runner_z1/0) which already has 2 apps running on it. 

The question: why the third app hasn't been sent to the second runner instance ? I'd expect some kind of load balancing; is my expectation correct ?

Which is the agorithm balancing the user deployed apps among the CF runner instances ?

And how is it customizable (if it is) ?

   Alvise

[Matthew Sykes]

Placement for staging and the first app instance: https://github.com/cloudfoundry/cloud_controller_ng/blob/e4e5294f1767257e294115da2a3c659f19a0ab94/lib/cloud_controller/dea/stager_pool.rb#L31

Placement for the nth app instance: https://github.com/cloudfoundry/cloud_controller_ng/blob/e4e5294f1767257e294115da2a3c659f19a0ab94/lib/cloud_controller/dea/pool.rb#L44-L50

Both select a subset of DEA's and randomly select one from that subset; placement is not deterministic with DEAs.  Diego's algorithms are different.

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Matthew Sykes
matthe...@gmail.com

[morika-t]

Hi Alvise

Can you show me your manifest?

Instances are distributed based on the zone

The current version of the algorithm of ccng is here

https://github.com/cloudfoundry/cloud_controller_ng/pull/122/files

https://github.com/cloudfoundry/cloud_controller_ng/blob/master/lib/cloud_controller/dea/pool.rb#L47
https://github.com/cloudfoundry/cloud_controller_ng/blob/master/lib/cloud_controller/dea/eligible_advertisement_filter.rb#L42-L46

2015年4月20日月曜日 16時57分00秒 UTC+9 alvi...@gmail.com:

[alvi...@gmail.com]

Hi Morika,

I had talked too early. After a while the system started to behave as expected. 

Even the rescaling of an app to 2 instances, seems to distribute the second one on the other runner instances.

thanks, and sorry for the noise.

    A.