I need to synchronize the indexes of two AWS ElasticSearch Service instances once a day.
It's really important that the synchronization is NOT real time. The first index (let's call it ES-A) is used internally by our team while the second index (ES-B) will be used by the public.
All modifications made by our team to ES-A during the day have to be pushed to ES-B during the night. Preferably, without downtime.
Here is a schema of our system. This question is about the thick green arrow:
What would be the best approach to achieve this behavior?
Keep in mind that I use AWS ES Service, not EC2 instances with ES on them.