Method: Chef::Resource#notifies

Defined in:

lib/chef/resource.rb

#notifies(action, resource_spec, timing = :delayed) ⇒ Object

Sets up a notification that will run a particular action on another resource if and when this resource is updated by an action.

If the action does not update this resource, the notification never triggers.

Only one resource may be specified per notification.

‘delayed` notifications will only ever happen once per resource, so if multiple resources all notify a single resource to perform the same action, the action will only happen once. However, if they ask for different actions, each action will happen once, in the order they were updated.

‘immediate` notifications will cause the action to be triggered once per notification, regardless of how many other resources have triggered the notification as well.

Examples:

Resource by string

file '/foo.txt' do
  content 'hi'
  notifies :create, 'file[/bar.txt]'
end
file '/bar.txt' do
  action :nothing
  content 'hi'
end

Resource by hash

file '/foo.txt' do
  content 'hi'
  notifies :create, file: '/bar.txt'
end
file '/bar.txt' do
  action :nothing
  content 'hi'
end

Direct Resource

bar = file '/bar.txt' do
  action :nothing
  content 'hi'
end
file '/foo.txt' do
  content 'hi'
  notifies :create, bar
end

Parameters:

• action —

  The action to run on the other resource.

• resource_spec (String, Hash, Chef::Resource) —

  The resource to run.

• timing (String, Symbol) (defaults to: :delayed) —

  When to notify. Has these values:

  • ‘delayed`: Will run the action on the other resource after all other actions have been run. This is the default.

  • ‘immediate`, `immediately`: Will run the action on the other resource immediately (before any other action is run).

  • ‘before`: Will run the action on the other resource immediately before the action is actually run.

# File 'lib/chef/resource.rb', line 242

def notifies(action, resource_spec, timing = :delayed)
  # when using old-style resources(:template => "/foo.txt") style, you
  # could end up with multiple resources.
  validate_resource_spec!(resource_spec)

  resources = [ resource_spec ].flatten
  resources.each do |resource|

    case timing.to_s
    when "delayed"
      notifies_delayed(action, resource)
    when "immediate", "immediately"
      notifies_immediately(action, resource)
    when "before"
      notifies_before(action, resource)
    else
      raise ArgumentError,  "invalid timing: #{timing} for notifies(#{action}, #{resources.inspect}, #{timing}) resource #{self} "\
        "Valid timings are: :delayed, :immediate, :immediately, :before"
    end
  end

  true
end