Upgrade from 6.8.12 oss to 7.9.2 basic

Greetings wonderful elasticsearch wizards!

I was wondering if there was any way to do a ROLLING UPGRADE from oss to basic? Specifically, we are looking to go from 6.8.12 oss to 7.9.2 elastic basic.

I do see in some posts, that there are api incompatibility issues mentioned, but I was wondering if there were work arounds... I did test it and was unsuccessful.

So far I tested (3 node clusters):

attempt 6.8.12 oss -> rolling upgrade -> 7.9.2 basic

  • can't install 7.9.2 basic dpkg over 6.8.12 oss dpkg.
  • attempt to purge/force-purge oss dpkg, fails
  • manually remove dpkg files, install 7.9.2 basic, seems garbled. elasticsearch won't start [fail]

attempt 6.8.12 oos -> wipe node - rolling upgrade ->7.9.2 basic

  • pulled 1 node, reimage, install 7.9.2 basic
  • new 7.9.2 basic node joins 6.8.12 oss cluster fine
  • ILM error messages in logs. (not sure if disabling index life management would help)
  • cluster replicates shard ok to 7.9.2 basic node fine.
  • search calls don't fail, but will return 0 results for the new node. so 1/3 of the cluster queries now return 0 results.
  • fail

attempt 6.8.12 oss -> REINDEX _source -> new 7.9.2 cluster

  • of course, works great.

attempt 6.8.12 oss -> rolling upgrade -> 7.9.2 oss

  • of course, works great.

so, is a full cluster restart really the only way to go from oss to basic? or is a rolling upgrade possible at all?

also, it's understandable that the elastic distro won't just install over the oss distro... but is there some special magic to purge .deb dpkgs?

Thanks!

I think my problems removing the elasticsearch-oss dpkg may have to do with docker and the PID 1/systemd assumption.

bump. anyone know if a rolling upgrade is possible from oss to basic?
or new apis require a full cluster restart? thanks!