[chef-client] Enable chef-client scheduled task to behave like cron, with predictable splay and start time

George Holt · George Holt · commit 7890004ee9e5 · 2021-08-03T17:03:25.000-04:00
Signed-off-by: George Holt &lt;gholtiii@me.com&gt;
diff --git a/.github/workflows/kitchen.yml b/.github/workflows/kitchen.yml
@@ -36,9 +36,9 @@ jobs:
       - name: Check out cookbook code
         uses: actions/checkout@master
       - name: Install Chef Infra Client
-        uses: actionshub/chef-install@master
+        uses: actionshub/chef-install@main
       - name: Dokken
-        uses: actionshub/kitchen-dokken@master
+        uses: actionshub/kitchen-dokken@main
         env:
           CHEF_LICENSE: accept-no-persist
           KITCHEN_LOCAL_YAML: kitchen.dokken.yml
diff --git a/README.md b/README.md
@@ -54,13 +54,15 @@ The chef_client_scheduled_task resource setups up Chef Infra Client to run as a
 - `frequency_modifier` Numeric value to go with the scheduled task frequency - default: '30'
 - `start_time` The start time for the task in HH:mm format (ex: 14:00). If the `frequency` is `minute` default start time will be `Time.now` plus the `frequency_modifier` number of minutes.
 - `start_date` - The start date for the task in `m:d:Y` format (ex: 12/17/2017). nil by default and isn't necessary if you're running a regular interval.
-- `splay` - A random number of seconds between 0 and X to add to interval. default: '300'
+- `splay` - A random number of seconds between 0 and X to add to interval. Note splay is applied differently when use_consistent_splay is set to true. default: '300'
 - `config_directory` - The path to the Chef config directory. default: 'C:/chef'
 - `log_file_name` - The name of the log file. default: 'client.log'
 - `log_directory` - The path to the Chef log directory. default: 'CONFIG_DIRECTORY/log'
 - `chef_binary_path` - The path to the chef-client binary. default: 'C:/opscode/chef/bin/chef-client'
 - `daemon_options` - An optional array of extra options to pass to the chef-client
 - `task_name` - The name of the scheduled task. This allows for multiple chef_client_scheduled_task resources when it is used directly like in a wrapper cookbook. default: 'chef-client'
+- `use_consistent_splay` - Indicates that the randomly computed splay should remain consistent for a given node, similar to how it functions in cron resource. default: false
+- `snap_time_to_frequency` - Indicates that the start day and time for the task should be snapped to start at the next frequency cycle after the previous top of the hour. For example if the current time is 14:07 and the frequency_modifier is 30, the next task start time should be 14:30. Only applicable when frequency = 'minute'.  default: false
 
 ### chef_client_cron
 
@@ -244,7 +246,7 @@ Use this recipe to run chef-client as a cron job rather than as a service. The c
 
 ### task
 
-Use this recipe to run chef-client on Windows nodes as a scheduled task. Without modifying attributes the scheduled task will run 30 minutes after the recipe runs, with each chef run rescheduling the run 30 minutes in the future. By default the job runs as the system user. The time period between runs can be modified with the `default['chef_client']['task']['frequency_modifier']` attribute and the user can be changed with the `default['chef_client']['task']['user']` and `default['chef_client']['task']['password']` attributes.
+Use this recipe to run chef-client on Windows nodes as a scheduled task. Without modifying attributes the scheduled task will run 30 minutes after the recipe runs, with each chef run rescheduling the run 30 minutes in the future. By default the job runs as the system user. The time period between runs can be modified with the `default['chef_client']['task']['frequency_modifier']` attribute and the user can be changed with the `default['chef_client']['task']['user']` and `default['chef_client']['task']['password']` attributes. For a scheduled task that behaves more like the chef-client cron job, the snap_time_to_frequency and use_consistent_splay properties can be set to true.
 
 ## Usage
 
diff --git a/attributes/default.rb b/attributes/default.rb
@@ -53,8 +53,8 @@
   'weekday' => '*',
   'path' => nil,
   'environment_variables' => nil,
-  'log_directory' => nil,
-  'log_file' => '/dev/null',
+  'log_directory' => '/dev',
+  'log_file' => 'null',
   'append_log' => false,
   'use_cron_d' => false,
   'mailto' => nil,
@@ -79,6 +79,8 @@
 default['chef_client']['task']['start_time'] = nil
 default['chef_client']['task']['start_date'] = nil
 default['chef_client']['task']['name'] = 'chef-client'
+default['chef_client']['task']['use_consistent_splay'] = false
+default['chef_client']['task']['snap_time_to_frequency'] = false
 
 default['chef_client']['load_gems'] = {}
 
diff --git a/kitchen.yml b/kitchen.yml
@@ -118,3 +118,8 @@ suites:
   run_list:
     - recipe[test::task]
   includes: ["windows-2012r2-13", "windows-2012r2-14", "windows-2016", "windows-2019"]
+
+- name: emulate-cron-task
+  run_list:
+    - recipe[test::emulate_cron_task]
+  includes: ["windows-2012r2-13", "windows-2012r2-14", "windows-2016", "windows-2019"]
diff --git a/libraries/helpers.rb b/libraries/helpers.rb
@@ -24,6 +24,20 @@ module Helpers
       include Chef::Mixin::Which
       require 'digest/md5'
 
+      #
+      # Snaps the start time of the scheduled task to the next start of the frequency cycle, where the frequency cycle begins
+      # at the top of the hour and increments by frequency_modifier in minutes
+      #
+      # @param [Integer] frequency_modifier - The frequency modifier in minutes
+      # @return [Time] The next snap-to time on the frequency cycle computed from top of the previous hour
+      #
+      def snap_time(frequency_modifier)
+        ref_time = Time.now
+        snap = Time.new(ref_time.year, ref_time.mon, ref_time.day, ref_time.hour, 0, 0)
+        minutes = (ref_time.min + frequency_modifier) - (ref_time.min % frequency_modifier)
+        snap + (minutes * 60)
+      end
+
       def wmi_property_from_query(wmi_property, wmi_query)
         @wmi = ::WIN32OLE.connect('winmgmts://')
         result = @wmi.ExecQuery(wmi_query)
diff --git a/recipes/task.rb b/recipes/task.rb
@@ -41,6 +41,8 @@ class ::Chef::Recipe
   chef_binary_path node['chef_client']['bin']
   daemon_options node['chef_client']['daemon_options']
   task_name node['chef_client']['task']['name']
+  use_consistent_splay node['chef_client']['task']['use_consistent_splay']
+  snap_time_to_frequency node['chef_client']['task']['snap_time_to_frequency']
 end
 
 windows_service 'chef-client' do
diff --git a/resources/cron.rb b/resources/cron.rb
@@ -20,6 +20,7 @@
 chef_version_for_provides '< 16.0' if respond_to?(:chef_version_for_provides)
 
 provides :chef_client_cron
+unified_mode true
 resource_name :chef_client_cron
 
 property :job_name, String, default: 'chef-client'
@@ -122,6 +123,7 @@ def log_command
   # @return [String]
   #
   def log_path
+    puts "Log directory='#{new_resource.log_directory}'"
     return new_resource.log_file_name if new_resource.log_directory.nil?
     ::File.join(new_resource.log_directory, new_resource.log_file_name)
   end
diff --git a/resources/scheduled_task.rb b/resources/scheduled_task.rb
@@ -20,6 +20,7 @@
 chef_version_for_provides '< 16.0' if respond_to?(:chef_version_for_provides)
 
 provides :chef_client_scheduled_task
+unified_mode true
 resource_name :chef_client_scheduled_task
 
 property :task_name, String,
@@ -40,6 +41,9 @@
   callbacks: { 'should be a positive number' => proc { |v| v > 0 } },
   default: lazy { frequency == 'minute' ? 30 : 1 }
 
+property :snap_time_to_frequency, [true, false],
+  default: false
+
 property :accept_chef_license, [true, false],
   default: false
 
@@ -54,6 +58,9 @@
   callbacks: { 'should be a positive number' => proc { |v| v > 0 } },
   default: 300
 
+property :use_consistent_splay, [true, false],
+  default: false
+
 property :run_on_battery, [true, false],
   default: true
 
@@ -93,7 +100,7 @@
     frequency_modifier             new_resource.frequency_modifier if frequency_supports_frequency_modifier?
     start_time                     start_time_value
     start_day                      new_resource.start_date unless new_resource.start_date.nil?
-    random_delay                   new_resource.splay if frequency_supports_random_delay?
+    random_delay                   new_resource.splay if frequency_supports_random_delay? && !new_resource.use_consistent_splay
     disallow_start_if_on_batteries new_resource.splay unless new_resource.run_on_battery || Gem::Requirement.new('< 14.4').satisfied_by?(Gem::Version.new(Chef::VERSION))
     action                         [ :create, :enable ]
   end
@@ -115,7 +122,17 @@ def full_command
     # Fetch path of cmd.exe through environment variable comspec
     cmd_path = ENV['COMSPEC']
 
-    "#{cmd_path} /c \"#{client_cmd}\""
+    "#{cmd_path} /c \"#{consistent_splay_command}#{client_cmd}\""
+  end
+
+  #
+  # The consistent splay sleep time when use_consistent_splay is true
+  #
+  # @return [NilClass,String] The prepended sleep command to run prior to executing the full command.
+  #
+  def consistent_splay_command
+    return unless new_resource.use_consistent_splay
+    "C:/windows/system32/windowspowershell/v1.0/powershell.exe Start-Sleep -s #{splay_sleep_time(new_resource.splay)} && "
   end
 
   #
@@ -157,6 +174,10 @@ def frequency_supports_frequency_modifier?
   def start_time_value
     if new_resource.start_time
       new_resource.start_time
+    elsif new_resource.snap_time_to_frequency && new_resource.frequency == 'minute'
+      snap_time = snap_time(new_resource.frequency_modifier)
+      new_resource.start_date = snap_time.strftime('%m/%d/%Y')
+      snap_time.strftime('%H:%M')
     elsif Gem::Requirement.new('< 13.7.0').satisfied_by?(Gem::Version.new(Chef::VERSION))
       new_resource.frequency == 'minute' ? (Time.now + 60 * new_resource.frequency_modifier.to_f).strftime('%H:%M') : nil
     end
diff --git a/resources/systemd_timer.rb b/resources/systemd_timer.rb
@@ -20,6 +20,7 @@
 chef_version_for_provides '< 16.0' if respond_to?(:chef_version_for_provides)
 
 provides :chef_client_systemd_timer
+unified_mode true
 resource_name :chef_client_systemd_timer
 
 property :job_name, String, default: 'chef-client'
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
@@ -5,4 +5,31 @@
   config.color = true               # Use color in STDOUT
   config.formatter = :documentation # Use the specified formatter
   config.log_level = :error         # Avoid deprecation notice SPAM
+
+  config.before do
+    # Mock chef_version_for_provides to be < 18 for chef_client_scheduled_task so that resource will be evaluated
+    # by current chef unit testing version
+    class Chef::Resource
+      class << self
+        alias_method :chef_version_for_provides_original, :chef_version_for_provides
+
+        def chef_version_for_provides(constraint)
+          if ::File.basename(__FILE__) == 'scheduled_task.rb'
+            '< 18.0' # Bump the constraint to current 17.x versions of Chef
+          else
+            chef_version_for_provides_original(constraint)
+          end
+        end
+      end
+    end
+    
+    unless RUBY_PLATFORM =~ /mswin|mingw32|windows/
+      # This enables spec testing of windows recipes on nix OSes. This is used
+      # to address the use of Win32::Service in recipe chef-client::task
+      Win32 = Module.new unless defined?(Win32)
+      Win32::Service = Class.new unless defined?(Win32::Service)
+      allow(::Win32::Service).to receive(:exists?).with(anything).and_return(false)
+      allow(::Win32::Service).to receive(:exists?).with('chef-client').and_return(true)
+    end
+  end
 end
diff --git a/spec/unit/scheduled_task_spec.rb b/spec/unit/scheduled_task_spec.rb
@@ -1,29 +1,60 @@
 # Chefspec and windows aren't the best of friends. Running this on a non-windows
 # host results in win32ole load errors.
 
-# require 'spec_helper'
-#
-# describe 'chef-client::task' do
-#   context 'when given override attributes' do
-#     let(:chef_run) do
-#       ChefSpec::ServerRunner.new(platform: 'windows', version: '2012R2', step_into: ['chef_client_scheduled_task']) do |node|
-#         node.override['chef_client']['task']['start_time'] = 'Tue Sep 13 15:46:33 EDT 2016'
-#         node.override['chef_client']['task']['user'] = 'system'
-#         node.override['chef_client']['task']['password'] = 'secret'
-#         node.override['chef_client']['task']['frequency'] = 'hourly'
-#         node.override['chef_client']['task']['frequency_modifier'] = 60
-#       end.converge(described_recipe)
-#     end
-#
-#     it 'creates the windows_task resource with desired settings' do
-#       expect(chef_run).to create_windows_task('chef-client').with(
-#         command: 'cmd /c "C:/opscode/chef/bin/chef-client -L C:/chef/log/client.log -c C:/chef/client.rb -s 300 ^> NUL 2^>^&1"',
-#         user: 'system',
-#         password: 'secret',
-#         frequency: :hourly,
-#         frequency_modifier: 60,
-#         start_time: 'Tue Sep 13 15:46:33 EDT 2016'
-#       )
-#     end
-#   end
-# end
+require 'spec_helper'
+
+describe 'chef-client::task' do
+  let(:local_system) { instance_double('LocalSystem', account_simple_name: 'system') }
+  let(:sid_class) { class_double('Chef::ReservedNames::Win32::Security::SID', LocalSystem: local_system, system_user?: true) }
+  let(:node) { runner.node }
+  let(:chef_run) { runner.converge(described_recipe) }
+  let(:runner) { ChefSpec::SoloRunner.new(platform: 'windows', version: '2012R2', step_into: ['chef_client_scheduled_task']) }
+
+  before do
+    # Mock up the environment to behave like Windows running Chef < 16
+    allow(ENV).to receive(:[]).and_call_original
+    allow(ENV).to receive(:[]).with('COMSPEC').and_return('cmd')
+    stub_const('Chef::ReservedNames::Win32::Security::SID', sid_class)
+    node.automatic['chef_client']['bin'] = 'C:/opscode/chef/bin/chef-client'
+    allow(Chef::Resource).to receive(:respond_to?).and_call_original
+    allow(Chef::Resource).to receive(:respond_to?).with(:chef_version_for_provides).and_return(true)
+    allow(Chef::Resource).to receive(:chef_version_for_provides).with('< 16.0').and_return(true)
+  end
+
+  context 'when given override attributes' do
+    before do
+      node.override['chef_client']['task']['start_time'] = '16:10'
+      node.override['chef_client']['task']['frequency'] = 'hourly'
+      node.override['chef_client']['task']['frequency_modifier'] = 1
+      node.override['chef_client']['daemon_options'] = ['-s', '300', '^>', 'NUL', '2^>^&1']
+    end
+
+    it 'creates the windows_task resource with desired settings' do
+      expect(chef_run).to create_windows_task('chef-client').with(
+        command: 'cmd /c "C:/opscode/chef/bin/chef-client -L C:/chef/log/client.log -c C:/chef/client.rb -s 300 ^> NUL 2^>^&1"',
+        user: 'SYSTEM',
+        frequency: :hourly,
+        frequency_modifier: 1,
+        start_time: '16:10'
+      )
+    end
+  end
+
+  context 'when configured to use a consistent splay and snap frequency time' do
+    let(:now) { Time.new('2021', '4', '15', '16', '7', '12') }
+    before do
+      node.override['chef_client']['task']['use_consistent_splay'] = true
+      node.override['chef_client']['task']['snap_time_to_frequency'] = true
+      allow(Time).to receive(:now).and_return(now)
+      allow_any_instance_of(Chef::Resource::ChefClientScheduledTask).to receive(:splay_sleep_time).and_return(222)
+    end
+
+    it 'creates the windows_task resource with desired settings' do
+      expect(chef_run).to create_windows_task('chef-client').with(
+                            command: 'cmd /c "C:/windows/system32/windowspowershell/v1.0/powershell.exe Start-Sleep -s 222 && C:/opscode/chef/bin/chef-client -L C:/chef/log/client.log -c C:/chef/client.rb"',
+                            start_day: '04/15/2021',
+                            start_time: '16:30'
+                          )
+    end
+  end
+end
diff --git a/test/cookbooks/test/recipes/cron.rb b/test/cookbooks/test/recipes/cron.rb
@@ -1,6 +1,5 @@
 apt_update 'update'
 include_recipe 'test::config'
-include_recipe 'cron::default'
 package 'crontabs' if platform?('fedora') # ensures we actually have the /etc/cron.d dir
 include_recipe 'chef-client::cron'
 include_recipe 'chef-client::delete_validation'
diff --git a/test/cookbooks/test/recipes/emulate_cron_task.rb b/test/cookbooks/test/recipes/emulate_cron_task.rb
@@ -0,0 +1,19 @@
+node.override['chef_client']['interval'] = 900
+node.override['chef_client']['task']['snap_time_to_frequency'] = true
+node.override['chef_client']['task']['use_consistent_splay'] = true
+
+include_recipe 'test::config'
+include_recipe 'chef-client::task'
+include_recipe 'chef-client::delete_validation'
+
+chef_client_scheduled_task 'Chef Client on start' do
+  user             node['chef_client']['task']['user']
+  password         node['chef_client']['task']['password']
+  frequency        'onstart'
+  config_directory node['chef_client']['conf_dir']
+  log_directory    node['chef_client']['log_dir']
+  log_file_name    node['chef_client']['log_file']
+  chef_binary_path node['chef_client']['bin']
+  daemon_options   node['chef_client']['daemon_options']
+  task_name        "#{node['chef_client']['task']['name']}-onstart"
+end
diff --git a/test/integration/emulate_cron_task/task_spec.rb b/test/integration/emulate_cron_task/task_spec.rb
@@ -0,0 +1,22 @@
+describe command('C:/opscode/chef/embedded/bin/ohai virtualization -c C:/chef/client.rb') do
+  its('exit_status') { should eq 0 }
+end
+
+describe file('C:/chef/client.rb') do
+  its('content') { should match(/ohai.disabled_plugins = \["Mdadm"\]/) }
+  its('content') { should match(/ohai.optional_plugins = \["Passwd"\]/) }
+  its('content') { should match(%r{ohai.plugin_path << "/tmp/kitchen/ohai/plugins"}) }
+end
+
+# the inspec resource requires PS 3.0+ and 2k8r2 only has PS 2.0 by default
+unless os.release.to_f == 6.1
+  describe windows_task('chef-client') do
+    it { should be_enabled }
+    its('run_as_user') { should eq 'SYSTEM' }
+    its('task_to_run') { should match %r{cmd.exe /c C:/windows/system32/windowspowershell/v1.0/powershell.exe Start-Sleep -s ([0-9]|[1-9][0-9]|[1-9][0-9][0-9]) C:/opscode/chef/bin/chef-client -L C:/chef/log/client.log -c C:/chef/client.rb -s 300} }
+  end
+
+  describe windows_task('chef-client-onstart') do
+    it { should be_enabled }
+  end
+end
