Actually, Ruby 2.0.0 won’t work. When I tried I got an error from the Sidekiq gem:
uninitialized constant Sidekiq::Sinatra
This was coming from sidekiq.web.rb:
module Sidekiq
class Web < Sinatra::Base
--------------^
sinatra/base is required above. While I don’t know Ruby, I guessed that this is a language incompatibility. And indeed, the error went away after switching to Ruby 2.1.2.
Interesting… I was under the impression that the Docker image used Ruby 2.1 but I see now that there are multiple images.
I am doing production Discourse but without Docker - using that with our setup is rather complicated to say the least.
The environment (Puppet-configured) was Ubuntu 12.04, Ruby 2.0.0 installed via RVM (it was 2.0.0-p645 I think), Postgresql 9.3 from apt.postgresql.org, jemalloc. The only thing I changed to make the error go away was asking RVM to install Ruby 2.1.