Today I looked at my Discourse installation and after rebuilding app image, somehow decided to check ruby version.
./launcher enter app
ruby 2.0.0p647 (2015-08-18 revision 51631) [x86_64-linux]
It really surprised me, because 2.0 branch is not officially supported anymore.
Am I doing something wrong? Or Discourse really use 2.0 ruby?
I started looking for PosgreSQL version and found 9.3.11. I found 9.5 template, but no info about how to upgrade to it. Is it not complete yet?
Answer Thanks to @sam