install solargraph via:
gem install solargraph
or add 'solargraph' in you Gemfile.
start solargraph server:
Clone this repository somewhere and add this directory to your load-path.
(require 'solargraph) (define-key ruby-mode-map (kbd "M-i") 'solargraph:complete)
(require 'ac-solargraph) (define-key ruby-mode-map (kbd "M-i") 'ac-solargraph:complete)
Solargraph project: https://github.com/castwide/solargraph