If you have nodes with different operating systems, such as Ubuntu and CentOS, you might want to deliver different files to each of them. There might be differences in the necessary configuration options and the like. Chef offers a way for files and templates to differentiate which version to use, based on a node's platform.
Make sure that you have a cookbook called my_cookbook and that the run_list of your node includes my_cookbook, as described in the Creating and using cookbooks recipe in Chapter 1, Chef Infrastructure.
Let's add two templates to our cookbook and see which one gets used:
Edit your cookbook's default recipe:
mma@laptop:~/chef-repo $ subl cookbooks/my_cookbook/recipes/default.rbtemplate "/tmp/message" do source "message.erb" end
Create a template as a default:
mma@laptop:~/chef-repo $ subl cookbooks/my_cookbook/templates/default/message.erbHello from default template!
Create a template...