If OneFlow doesn’t start and you find this in your /var/log/one/oneflow.error:

/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require': no such file to load -- treetop (LoadError)
from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from /usr/lib/one/oneflow/lib/models/role.rb:17
from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from /usr/lib/one/oneflow/lib/models.rb:26
from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from /usr/lib/one/oneflow/oneflow-server.rb:49


Then do:

gem install treetop polyglot parse-cron

Although treetop is in EPEL (as rubygem-treetop.noarch) you get this when you try to install it:

Error: Package: rubygem-treetop-1.4.10-1.el6.noarch (epel)
Requires: rubygem(polyglot)


It depends on polyglot but polyglot is not in EPEL – how stupid is that? And nowhere else to be found. Some other 3rd party repos claim to have it but adding another repo just for a single ruby gem – no thanks.

And you also need parse-cron, sigh.