Pre convergence notifications

gistfile1.rb

Chef::Config[:why_run] = true
t = package "cassandra" do
  version '42'
  action :nothing
end
t.run_action(:install)
would_update = t.updated_by_last_action?
Chef::Config[:why_run] = false


execute "downtime in supervision" do
  cmd "do it!"
  only_if { t.updated_by_last_action? } #this doesn't work
end

execute "dowtime in supervision" do
  cmd "do it!"
  only_if { would_update} #this works
end


#after resetting why run everything runs as usual
b= package "screen"

#so we can now really update the package
package "cassandra" do
  version '42'
  action :install
end

lwrp_tentative.rb

#resource prehook
actions :run
default_action :run

attribute :resource, :kind_of => Resource, :required => true
attribute :hooked_action, :kind_of => Symbol, :default => :nothing

#provider prehook
action :run do
  previous_why_run_mode = Chef::Config[:why_run]
  Chef::Config[:why_run] = true
  new_resource.resource.run_action(new_resource.hooked_action)
  would_be_updated = new_resource.resource.updated_by_last_action?
  Chef::Config[:why_run] = previous_why_run_mode
  new_resource.resource.action(new_resource.hooked_action)
  new_resource.updated_by_last_action(would_be_updated)
end

#Usage
p = package "cassandra" do
  action :nothing
end

execute "downtime" do
  command "touch /tmp/downtime"
  action :nothing
end

prehook "toto" do
  resource p
  hooked_action :install
  notifies :run, "execute[downtime]"
end