In a recipe I want to check to see if a service is installed, and if it is not notify the 3 resources needed to install it. I tried the service resource, which correctly identifies the service when it is installed, but throws an exception if the service is not installed.
I'm not sure what action to use here. :nothing just skips the resource so it ever get executed, but any of the other actions will error when they attempt to act on a service that doesn't exist.
How do I detect whether a service is installed and act based on that information?
I'm running on Windows, if that's relevant.
Take a look on how is service for windows is defined
https://github.com/opscode/chef/blob/master/lib/chef/provider/service/windows.rb
AFAIU its pretty straighforward add import to your recipe:
require 'win32/service'
and then you can check if service exists with
Win32::Service.exists?(@new_resource.service_name)
voila - you can put impementation to library (http://docs.opscode.com/essentials_cookbook_libraries.html) just not to pollute recipe code and have simple method service_exists?.
来源：https://stackoverflow.com/questions/20131754/chef-how-do-i-check-to-see-if-a-service-is-installed