I have successfully moved our Zabbix server v4.0.3 to Elasticsearch v7.2.1, using slight modifications to the official Zabbix documentation for Elasticsearch setup, and a minor change to the Frontend CHistoryManager.php source.

Required change to curl commands for creating mappings/index-templates:

The request parameter "include_type_name" must be added to the url, due to the deprecation of "types" in v7 (reference: https://www.elastic.co/guide/en/elasticsearch/reference/master/indices-put-mapping.html)

Example:

curl -X PUT \
http://your-elasticsearch.here:9200/_template/uint_template?include_type_name=true \
-H 'content-type:application/json' \
-d '{
  ...
}'

Required changes to PHP front-end for graph rendering:

The file 'CHistoryManager.php' is currently using a method deprecated in the Elasticsearch Painless API

.. doc[\'clock\'].date.getMillis() ..

The supported alternative method is:

.. doc[\'clock\'].value.toInstant().toEpochMilli() ..

(reference: https://www.elastic.co/guide/en/elasticsearch//reference/current/breaking-changes-7.0.html#_scripting_with_dates_should_use_java_time_based_methods)

(the actual diff is attached to this ticket)

I don't know if that change would be backwards compatible – it seems possible given the change is to use Java methods, but I have no way to test at this time.

As far as I can tell, everything is working as expected with no other changes.