whenever_with_cap_multistage.rb

require 'whenever/capistrano'

##
# Force Whenever to use the Capistrano stage. We use a lambda to delay execution
# until absolutely necessary.
set :whenever_command, lambda { "whenever --set environment=#{fetch(:stage, 'production')}" }

Whenever actually comes with a very similar, and configurable, Capistrano task. What I'm doing in my gist is modifying their setting for the "whenever" executable so that it dynamically sets the environment to use based on the current Capistrano environment used (e.g. staging, dev, production).