As a user I'd like a supported way to configure where Elasticsearch indices are located

Problem Definition

Currently there is no way to determine how much disk space Elasticsearch indices will need prior to installation and allowing the service to run.

This poses a risk of running out of disk space and the mission critical job of reading and writing repo data would be interrupted due to the search data that should be somewhat easy to separate. 

Suggested Solution

Provide a supported way of configuring where the indices are located. If space becomes an issue additional filesystems/volumes sufficient room can be added.

Workaround

A potential workaround might be symlinking the $BITBUCKET_HOME/shared/search/data to another location or creating a mount point for NFS.