Sample ~/.ssh/config section:

Host *.arvados
  ProxyCommand ssh -p2222 turnout@switchyard.<%= Rails.configuration.arvados_v1_base.match(/\/\/(.*?)\//).andand[1] || 'xyzzy.arvadosapi.com' %> -x -a $SSH_PROXY_FLAGS %h
<% if @objects.first.current_user_logins.andand.first %>
  User <%= @objects.first.current_user_logins.andand.first %>
<% end %>

Sample login command:

ssh <%= @objects.first.andand.hostname.sub(/\..*/,'') or 'vm-hostname' %>.arvados

See also: <%= link_to raw('Arvados Docs → User Guide → SSH access'), 'http://doc.arvados.org/user/ssh-access.html' %>.