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From Imesh Gunaratne <>
Subject Re: Manual scaling effects are not persisted
Date Wed, 15 Oct 2014 10:56:38 GMT
I do not think we need to specifically handle this, manual scaling also
need to take the same path as the standard scaling decision.

On Wed, Oct 15, 2014 at 10:03 AM, Rajkumar Rajaratnam <>

> Or else, we can have an API at CC side to update clusters and let CC to
> publish ClusterUpdated event to topology topic. AS can simply listen to
> this event and update the cluster context accordingly. Then we don't need
> to introduce a new topic for AS to publish events and AS is already
> listening to topology topic. IMO, this is a good approach.
> Wdyt?
> On Wednesday, October 15, 2014, Rajkumar Rajaratnam <>
> wrote:
>> Hi,
>> As you know, we are now supporting manual scaling for docker containers.
>> Autoscaler has an API to update cluster properties like min replicas of a
>> particular cluster.
>> void updateClusterMonitor(String clusterId, Properties properties) throws
>> InvalidArgumentException;
>> We are not persisting anything about clusters at AS side, when we
>> shutdown stratos. When we are restarting, we are reading topology and
>> create/populate/update cluster monitors.
>> Hence this new value for min replicas is not persisted when we shutdown
>> the stratos. During manual scaling the min replicas is updated only in AS
>> side, hence if we restart the stratos, this effect will be lost.
>> So manual scaling should impact the topology. Here is a proposed solution.
>> AS will provide an API to update cluster monitors, that is you can update
>> properties of a cluster like min replicas. Once this API is called AS will
>> send a *ClusterAltered* event to CC. Once CC gets this event, it will
>> validate the properties, update the topology and send a *ClusterUpdated*
>> event. Once AS gets this event, AS will update the cluster context with new
>> values for properties like min replicas. Until we get cluster updated
>> event, AS will not alter any properties.
>> Then everything is consistent and manual scaling effects will be
>> persisted.
>> wdyt?
>> Thanks.
>> --
>> Rajkumar Rajaratnam
>> Software Engineer | WSO2, Inc.
>> Mobile +94777568639 | +94783498120
> --
> Rajkumar Rajaratnam
> Software Engineer | WSO2, Inc.
> Mobile +94777568639 | +94783498120

Imesh Gunaratne

Technical Lead, WSO2
Committer & PMC Member, Apache Stratos

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