Chef version checking in recipes

default.rb

# access chef's version constant directly

if Chef::VERSION.to_f >= 0.8
  # 0.8+ only features here
end

# node attribute, requires ohai version 0.5.4:

if node.chef_packages.chef.version.to_f >= 0.8
  # 0.8+ only features here
end

Gem::Requirement.new(">= 0.8").satisfied_by?(Gem::Version.new(Chef::VERSION))

or Chef::VERSION >= 13.0 in recent enough chef-client where Chef::VERSION is a Chef::VersionString object.