Blog

vipin@laptop:~/chef-repo $ subl roles/web_servers.rb 
name "web_servers" 
description "This role contains nodes, which act as web servers" 
run_list "recipe[ntp]" 
default_attributes 'ntp' => { 
   'ntpdate' => { 
      'disable' => true 
   } 
}

vipin@laptop:~/chef-repo $ knife role from file web_servers.rb 

vipin@laptop:~/chef-repo $ knife node edit server 
"run_list": [ 
   "role[web_servers]" 
] 
Saving updated run_list on node server 

user@server:~$ sudo chef-client 
...TRUNCATED OUTPUT... 
[2013-07-25T13:28:24+00:00] INFO: Run List is [role[web_servers]] 
[2013-07-25T13:28:24+00:00] INFO: Run List expands to [ntp] 
...TRUNCATED OUTPUT... 

• Define a role in a Ruby file inside the roles folder of Chef repository.
• A role consists of a name and a description attribute.
• A role consists of role-specific run list and role-specific attribute settings.
• Every node that has a role in its run list will have the role’s run list exacted into its own.
• All the recipes in the role’s run list will be executed on the node.
• The role will be uploaded to Chef server using the knife role from file command.
• The role will be added to the node run list.
• Running Chef client on a node having the role in its run list will execute all the recipes listed in the role.