Add a pipeline to migrate ElastiFlow v1 data to new v2 data model

[robcowart]

Add a pipeline to migrate ElastiFlow v1 data to new v2 data model

[robcowart]

Now that ElastiFlow process sFlow and IPFIX in addition to Netflow, the index name netflow-* didn't really apply any more. The same applies to the field names to which everything is normalized, hence the change to flow. Since all of the Kibana elements are now prefixed with ElastiFlow: instead of Netflow: you can import the new dashboards without overwriting the old ones. That allows you to continue using the v1.x dashboards for the v1 data, and the v2.0 dashboards for the v2 data.

Ideally you would reindex the old data to the new data format. That could be achieved with a Logstash pipeline designed for that purpose. I will work on something, but probably won't have time to get to it for a couple weeks.

[robcowart]

Versioning of indices and index templates has been added in version 3.0.0. In the future this will allow for methods to be provided for the migration of historical data to newer versions. This won't help with older versions, but should help avoid such issues in the future.