Hello!
In documentation it is written that frontend service is stateless and could be scaled out or in at any time. What about other services?
All 4 roles should be stateless so your system can scale horizontally as you add more instances of a specific role.
More info in this forum post that might be helpful.
Thanks for reply. It is clear that adding more instances is allowed, but what about removing?
Yes, removing is also fine, assuming that the remaining instances can keep up with the load.