Are there any modifying operations that use HTTP word GET in Elastic Search? Or is it safe in a way to be able to access data without modifications while using HTTP GET request?
(Considering exposing a free form GET call to an index from internally accessible endpoint)
No.
All calls that modify the data in some way use PUT or POST. This is consistent with how the HTTP semantics were supposed to work.
There has been some pretty significant normative text that has been written about this subject and for the most part I have seen Elasticsearch conform to that. The same can't be said for all REST APIs that I have encountered.
