I'm running ES cluster with multiple on AWS. The cluster is behind an ELB that is fed by logstash. I've tested a new mapping template in a sandbox cluster, but with only one node.
I've read over these two articles:
https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-templates.html
https://www.elastic.co/blog/changing-mapping-with-zero-downtime
When changing the template does each node need to have an updated copy? Can the new template be fed to the master and then it will share the template?