How to install and configure elasticsearch for nextcloud?
install elasticsearch to your server
make sure that selfsigner SSL is accepted in config of nextcloud apps for fullsearch
run this command:
/usr/share/elasticsearch/bin/elasticsearch-reset-password -u elastic
After this answer yes and copy new password for elastic user
and then go to nextcloud fullsearch settings:
https://elastic:NEWGENERATEDANDCOPIEDPASSWORD@127.0.0.1:9200/