As an operator of Elasticsearch, I want to run on a supported OS so that I can benefit from security updates and general support.
Upgrade to Debian Bullseye has started at WMF (T275873: Prepare our base system layer for Debian 11/bullseye), Elasticsearch needs to follow the upgrades. This make sense to do as part of the Elastic 7.x migration (T263142: [EPIC] Upgrade Elasticsearch to version 7.x). Bullseye provides OpenJDK 11 and 17, we might want to upgrade the JDK at the same time (or use an OpenJDK 8 backport). Note that OpenJDK 17 isn't officially supported by Elasticsearch.
Note that we still haven't migrated to Buster (T244736: Migrate Elasticsearch to Debian Buster).
The following roles are all deployed on top of Debian Bullseye: