update Gemfile

config/deploy/production.rb

@@ -16,7 +16,11 @@ set :full_app_name, "#{fetch(:application)}_#{fetch(:stage)}"
 
 
 server 'ec2-54-169-212-254.ap-southeast-1.compute.amazonaws.com', user: 'ubuntu', roles: %w{web app db}, primary: true
-ssh_options[:keys] = %w(ssh/nemo.pem)
+set :ssh_options, {
+  keys: %w(/home/deploy/nemo_encoder/ssh/nemo.pem),
+  forward_agent: false,
+  user: 'ubuntu'
+} 
 
 set :deploy_to, "/home/#{fetch(:deploy_user)}/apps/#{fetch(:full_app_name)}"
 set :rbenv_ruby, '2.3.1'