Hello Jörg,
I think he stores files (oOo, Office, pdf...) on openstack swift space (a dropbox like feature) and want to index them.
He did not say that he wants to run ES on a openstack cloud.
So, I suppose that a river makes sense here.
My 2 cents.
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David 
Twitter : @dadoonet / @elasticsearchfr / @scrutmydocs
Le 13 janv. 2013 à 10:47, Jörg Prante joergprante@gmail.com a écrit :
Can you explain why a river?
From what I understand, OpenStack is a cloud service like Amazon AWS, not really a source for a river.
There is a cloud-aws plugin, which supersedes the zen discovery (and and obsoleted S3 shared storage) but that is all I know about ES cloud support yet.
I'm very enthusiastic about JClouds http://www.jclouds.org
"jclouds tests support of 30 cloud providers and cloud software stacks including Amazon, GoGrid, Ninefold, vCloud, OpenStack, and Azure."
By managing compute nodes and blob stores, JClouds could be the starting point for an ES launch tool and a discovery plugin (maybe based on the zookeeper plugin at https://github.com/sonian/elasticsearch-zookeeper) for more than 30 cloud infrastructures!
If someone would like to start work on this, it would be very, very exciting.
My favorite is also OpenStack since everybody can build OpenStack private clouds because it is open source.
Cheers,
Jörg
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