Using Helper.is_ci?

Fastfile

# Example of only doing something in or out of ci.
#=> fastlane my_process
#=> JENKINS_URL=foo fastlane my_process

before_all do
  ci_stuff
end

lane :my_process do 
  UI.message "Only do this when in CI" if Helper.is_ci?
  UI.message "Only do this when out of CI" unless Helper.is_ci?
end

def ci_stuff 
  return unless Helper.is_ci?
  UI.message "Doing CI setup actions"

  # For Example... 
  # unlock_keychain
  # cocoapods
end