[windows] Add option to support EXE Agent installer

README.md

@@ -66,10 +66,20 @@ dd-agent
 --------
 Installs the Datadog agent on the target system, sets the API key, and start the service to report on the local system metrics
 
-**Note for Windows**: With Chef >= 12.6 _and_ the `windows` cookbook >= 1.39.0, Agent upgrades are known to fail.
-For Chef>=12.6 users on Windows, we recommend pinning the `windows` cookbook to a lower version (`~> 1.38.0` for instance).
-If that's not an option, a known workaround is to use the `remove-dd-agent` recipe (since the `2.5.0` version of the present cookbook) to uninstall the Agent
-prior to any Agent upgrade.
+**Notes for Windows**:
+
+* With Chef >= 12.6 _and_ the `windows` cookbook >= 1.39.0, Agent upgrades are known to fail.
+  For Chef>=12.6 users on Windows, we recommend pinning the `windows` cookbook to a lower version (`~> 1.38.0` for instance).
+
+  If that's not an option, a known workaround is to use the `remove-dd-agent` recipe (since the `2.5.0` version of the present cookbook) to uninstall the Agent
+  prior to any Agent upgrade.
+
+* Because of changes in the Windows Agent packaging and install in version 5.12.0, when upgrading the Agent from versions <= 5.10.1 to versions >= 5.12.0,
+  please set the `windows_agent_use_exe` attribute to `true`.
+
+  Once the upgrade is complete, you can leave the attribute to its default value (`false`).
+
+  For more information on these Windows packaging changes, see the related [docs on the dd-agent wiki](https://github.com/DataDog/dd-agent/wiki/Windows-Agent-Installation).
 
 dd-handler
 ----------

attributes/default.rb

@@ -111,6 +111,13 @@
 # Expected checksum to validate correct agent installer is downloaded (Windows only)
 default['datadog']['windows_agent_checksum'] = nil
 
+# Set to `true` to use the EXE installer on Windows, recommended to gracefully handle upgrades from per-user
+# to per-machine installs on most environments. We recommend setting this option to `true` for Agent upgrades from
+# versions <= 5.10.1 to versions >= 5.12.0.
+# The EXE installer exists since Agent release 5.12.0
+# If you're already using version >= 5.12.0 of the Agent, leave this to false.
+default['datadog']['windows_agent_use_exe'] = false
+
 # Values that differ on Windows
 # The location of the config folder (containing conf.d)
 # The name of the dd agent service

recipes/_install-windows.rb

@@ -24,29 +24,66 @@
     node['datadog']['agent_version']
   end
 
-# If no version is specified, select the latest package
-dd_agent_msi = dd_agent_version ? "ddagent-cli-#{dd_agent_version}.msi" : 'ddagent-cli.msi'
-temp_file = ::File.join(Chef::Config[:file_cache_path], 'ddagent-cli.msi')
+# If no version is specified, select the latest package.
+# The latest package basename is `ddagent-cli-latest` since Agent version 5.12.0
+dd_agent_installer_basename = dd_agent_version ? "ddagent-cli-#{dd_agent_version}" : 'ddagent-cli-latest'
+temp_file_basename = ::File.join(Chef::Config[:file_cache_path], 'ddagent-cli')
+
+if node['datadog']['windows_agent_use_exe']
+  dd_agent_installer = "#{dd_agent_installer_basename}.exe"
+  temp_file = "#{temp_file_basename}.exe"
+  installer_type = :custom
+  install_options = '/q'
+else
+  dd_agent_installer = "#{dd_agent_installer_basename}.msi"
+  temp_file = "#{temp_file_basename}.msi"
+  installer_type = :msi
+  # Agent >= 5.12.0 installs per-machine by default, but specifying ALLUSERS=1 shouldn't affect the install
+  install_options = '/norestart ALLUSERS=1'
+end
+
+# Use a separate resource without a `source` so that it looks in the Registry to find the MSI to use
+# for the package removal
+# On Chef >= 12.6, we have to use the `package` resource instead of `windows_package` to allow not specifying a source
+# (this is related to the way the windows cookbook changes the provider of `windows_package` depending on the
+# version of Chef, and to improvements on the `package` resource made in Chef 12.6)
+# FIXME: when we remove Chef < 12.6 support on Windows, which should allow using core resources only
+use_windows_package_resource = Gem::Version.new(Chef::VERSION) < Gem::Version.new('12.6.0')
+if use_windows_package_resource
+  windows_package 'Datadog Agent removal' do
+    package_name 'Datadog Agent'
+    action :nothing
+  end
+else
+  package 'Datadog Agent removal' do
+    package_name 'Datadog Agent'
+    action :nothing
+  end
+end
 
 package_retries = node['datadog']['agent_package_retries']
 package_retry_delay = node['datadog']['agent_package_retry_delay']
 
 # Download the installer to a temp location
 remote_file temp_file do
-  source node['datadog']['windows_agent_url'] + dd_agent_msi
+  source node['datadog']['windows_agent_url'] + dd_agent_installer
   checksum node['datadog']['windows_agent_checksum'] if node['datadog']['windows_agent_checksum']
   retries package_retries unless package_retries.nil?
   retry_delay package_retry_delay unless package_retry_delay.nil?
   # As of v1.37, the windows cookbook doesn't upgrade the package if a newer version is downloaded
   # As a workaround uninstall the package first if a new MSI is downloaded
-  notifies :remove, 'windows_package[Datadog Agent]', :immediately
+  if use_windows_package_resource
+    notifies :remove, 'windows_package[Datadog Agent removal]', :immediately
+  else
+    notifies :remove, 'package[Datadog Agent removal]', :immediately
+  end
 end
 
 # Install the package
 windows_package 'Datadog Agent' do # ~FC009
   source temp_file
-  installer_type :msi
-  options '/norestart ALLUSERS=1'
+  installer_type installer_type
+  options install_options
   action :install
   success_codes [0, 3010]
 end

spec/dd-agent_spec.rb

@@ -144,7 +144,7 @@ def set_env_var(name, value)
     end
 
     context 'on Windows' do
-      cached(:chef_run)  do
+      cached(:chef_run) do
         set_env_var('ProgramData', 'C:\ProgramData')
         ChefSpec::SoloRunner.new(
           :platform => 'windows',
@@ -155,7 +155,25 @@ def set_env_var(name, value)
         end.converge described_recipe
       end
 
-      it_behaves_like 'windows Datadog Agent'
+      it_behaves_like 'windows Datadog Agent', :msi
+    end
+
+    context 'on Windows with EXE installer' do
+      cached(:chef_run) do
+        set_env_var('ProgramData', 'C:\ProgramData')
+        ChefSpec::SoloRunner.new(
+          :platform => 'windows',
+          :version => '2012R2',
+          :file_cache_path => 'C:/chef/cache'
+        ) do |node|
+          node.set['datadog'] = {
+            'api_key' => 'somethingnotnil',
+            'windows_agent_use_exe' => true
+          }
+        end.converge described_recipe
+      end
+
+      it_behaves_like 'windows Datadog Agent', :exe
     end
   end
 
@@ -231,7 +249,7 @@ def set_env_var(name, value)
 
       temp_file = ::File.join('C:/chef/cache', 'ddagent-cli.msi')
 
-      it_behaves_like 'windows Datadog Agent'
+      it_behaves_like 'windows Datadog Agent', :msi
       # remote_file source gets converted to an array, so we need to do
       # some tricky things to be able to regex against it
       # Relevant: http://stackoverflow.com/a/12325983
@@ -286,7 +304,7 @@ def set_env_var(name, value)
 
       temp_file = ::File.join('C:/chef/cache', 'ddagent-cli.msi')
 
-      it_behaves_like 'windows Datadog Agent'
+      it_behaves_like 'windows Datadog Agent', :msi
       # remote_file source gets converted to an array, so we need to do
       # some tricky things to be able to regex against it
       # Relevant: http://stackoverflow.com/a/12325983

spec/shared_examples.rb

@@ -72,20 +72,25 @@
   end
 end
 
-shared_examples_for 'windows Datadog Agent' do
+shared_examples_for 'windows Datadog Agent' do |installer_extension|
   it_behaves_like 'common windows resources'
 
-  agent_installer = 'C:/chef/cache/ddagent-cli.msi'
+  agent_installer = "C:/chef/cache/ddagent-cli.#{installer_extension}"
 
   it 'downloads the remote file only if it\'s changed' do
     expect(chef_run).to create_remote_file(agent_installer)
   end
 
-  it 'notifies the removal of the Datadog Agent' do
-    expect(chef_run.remote_file(agent_installer)).to notify('windows_package[Datadog Agent]').to(:remove)
+  it 'doesn\'t remove existing version of the Datadog Agent by default' do
+    expect(chef_run.package('Datadog Agent removal')).to do_nothing
+  end
+
+  it 'notifies the removal of the Datadog Agent when a remote file is downloaded' do
+    expect(chef_run.remote_file(agent_installer)).to notify('package[Datadog Agent removal]').to(:remove)
   end
 
   it 'installs Datadog Agent' do
-    expect(chef_run).to install_windows_package('Datadog Agent')
+    installer_type = installer_extension == :msi ? :msi : :custom
+    expect(chef_run).to install_windows_package('Datadog Agent').with(installer_type: installer_type)
   end
 end