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From Satish Mittal <satish.mit...@gmail.com>
Subject synchronize installation across services at cluster level
Date Thu, 08 Aug 2013 06:54:14 GMT

Let's say I have my cluster topology like:

whirr.instance-templates=1 service-A+service-B, 1 service-A+service-B

In my scenario, service-B should first wait for all service-A instances to
come up, so that I can create some tables and populate data on only one
instance of service-B.

For this purpose, I first need a callback after service-A has been
installed on all cluster instances, so that I can perform certain one-time
activities at that point. Do we already have such a callback in whirr
interfaces? I checked out ClusterActionHandler interface, but my
understanding is that it applies at role level on each instance. So
bootstrap/configure/start/stop get called for each instance of service-A. I
couldn't find a callback when all service-A instances are installed.

Additionally, is it possible to synchronize installation/starting of
service-B only after all instances of service-A are installed/started?
Basically, I am looking for a DAG kind of dependency mechanism to be
configured across services.


"The happiest of people donĀ“t necessarily have the best of everything, they
just make the most of everything that comes along their way."

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