Chef and DSC
DSC is a new management platform in Windows PowerShell that
enables deploying and managing configuration data for software services and
managing the environment in which these services run.
DSC provides a set of Windows PowerShell language
extensions, new Windows PowerShell cmdlets, and resources that you can use to
declaratively specify how you want your software environment to be configured.
It also provides a means to maintain and manage existing configurations.
With the release of Chef Client 11.16.0 PowerShell Desired
State Configuration (DSC) support was introduced into Chef Client for Windows.
With this feature DSC resources can be executed from Chef. Both DSC and chef
are similar in the way that both are idempotent, take similar approaches to the
concept of resources, describe the configuration of a system, and then take the
steps required to do that configuration. The most important difference between
Chef and DSC is that Chef uses Ruby and DSC is exposed as configuration data
from within Windows PowerShell. The dsc_resource resource allows any DSC
resource to be used in a Chef recipe, as well as any custom resources that have
been added to your Windows PowerShell environment.
The syntax for using the dsc_resource resource in a recipe
is as follows:
dsc_resource "name" do
resource :dsc_resource_name
property :dsc_property_name, "property_value"
property ...
...
end
For e.g the below given code shows how the windowsfeature
resource is used to install asp.net 4.5 on the node.
dsc_resource 'aspnet' do
resource :windowsfeature
property :ensure, 'Present'
property :name, "web-asp-net45"
end
LCM and WMF 5.0
Before using the dsc_resource, you need to ensure that
Windows Management Framework 5.0 is installed on the target node. Also the refresh
mode of the LCM should be set to disabled. To set the LCM refresh mode to
disabled, you can create a configuration as given below and execute it.
Configuration LCMSettings {
Node $env:COMPUTERNAME {
LocalConfigurationManager
{
RefreshMode =
"Disabled"
}
}
}
LCMSettings
Creating a cookbook for using DSC resources
To use the DSC resources, create a cookbook and edit the
default.rb file in recipes folder to add the content as given below.
dsc_resource 'iis' do
resource
:windowsfeature
property
:ensure, 'Present'
property
:name, "web-server"
end
dsc_resource
'aspnet' do
resource
:windowsfeature
property
:ensure, 'Present'
property
:name, "web-asp-net45"
end
dsc_resource
'defaulthtml' do
resource
:file
property
:ensure, 'Present'
property
:type, 'File'
property
:destinationpath, 'C:\inetpub\wwwroot\index.htm'
property
:contents, 'html of the page'
end
dsc_resource 'iisstart' do
resource
:file
property
:ensure, 'Absent'
property
:type, 'File'
property
:sourcepath, 'C:\inetpub\wwwroot\iisstart.htm'
property
:destinationpath, 'C:\inetpub\wwwroot\iisstart.htm'
end
Upload the cookbook to the server and chef the chef server
whether the cookbook is available.
Bootstrapping the chef client
To apply the configuration on the machine, use the command
knife bootstrap windows winrm cheftestvm00.cloudapp.net -x ‘user’ -P 'password'
-r "recipe[azurewebrole]"
After executing the command, you can access the default url
for the server and check whether the contents match the one given in the file
resource.
