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PowerShell – Creating DSC module – Part 3

logo-powershell-520x245We continue today with our DSC module creation. If you have been following this blog in recent days you might have noticed me posting information about good practices and idea I had to create this module. To keep up with the series you might want to visit :

  1. Part 1
  2. Part 2
  3. DSC Best practices

Since we can say we get smarter everyday its time to do …

Recap :

  • First of all we need to re-think the whole purpose of creating 2 resources for appPool management (here I refer to managing appPool defaults and remaining appPools). Why should we reconsider ? Well simply because with my original approach I’m unnecessarly duplicating data. As every application pool has the same properties as the default one … whats the point of having 2 resources ? well there isnt – so we are going to change that
  • Another one is appropiate naming of script responsible for naming resource. So lets go and start off with…

Structuring files the right way

By following point 21 from this recently mentioned DSC checklist we will be putting script which creates our resources into folder

C:\Program Files\WindowsPowerShell\Modules\cWebAdmin\DSCResources\RafPe_cWebAppPool\ResourceDesignerScripts

The file will be named accordingly to best practices – so using Generate<ResourceName>Schema.ps1 . So I have ended up having GenerateCwebAppPoolSchema.ps1

So we got this sorted. I have cleaned up GitHub project from unnecessary files and now it will only contain resource for cWebAppPool

 

Creating DSC resource

So now after all of this excercises we can go ahead and create our resource. At this stage 🙂 there is no guaratee that it will all work out of the box 😀 but we will do our best.  You think probably that you can get the coffee before we finish…. well not really 😀 I have prepared the file already for you so by just copying the code below we will be able to get our resource in no time (up to date version of this file in as usual on GiHub – code showed here is for learning purposes more )

   $Ensure                         = New-xDscResourceProperty -Name Ensure -Type String -Attribute Write -ValidateSet 'Present', 'Absent'
   $name                           = New-xDscResourceProperty –Name Name –Type String –Attribute Key		
   $queueLength                    = New-xDscResourceProperty –Name queueLength –Type String –Attribute Write		
   $autoStart                      = New-xDscResourceProperty –Name autoStart –Type String –Attribute Write
   $enable32BitAppOnWin64          = New-xDscResourceProperty –Name enable32BitAppOnWin64 –Type string –Attribute Write -ValidateSet 'true','false'
   $managedRuntimeVersion          = New-xDscResourceProperty –Name managedRuntimeVersion –Type string –Attribute Write -ValidateSet 'v4.0','v2.0',''
   $managedRuntimeLoader           = New-xDscResourceProperty –Name managedRuntimeLoader –Type string –Attribute Write
   $enableConfigurationOverride    = New-xDscResourceProperty –Name enableConfigurationOverride –Type string –Attribute Write  -ValidateSet 'true','false'
   $managedPipelineMode            = New-xDscResourceProperty –Name managedPipelineMode –Type string –Attribute Write -ValidateSet 'Integrated','Classic'
   $CLRConfigFile                  = New-xDscResourceProperty –Name CLRConfigFile –Type string –Attribute Write
   $passAnonymousToken             = New-xDscResourceProperty –Name passAnonymousToken –Type string –Attribute Write -ValidateSet 'true','false'
   $startMode                      = New-xDscResourceProperty –Name startMode –Type string –Attribute Write -ValidateSet 'AlwaysRunning','OnDemand'
   $identityType                   = New-xDscResourceProperty –Name identityType –Type string –Attribute Write -ValidateSet 'ApplicationPoolIdentity','LocalSystem','LocalService','NetworkService','SpecificUser'
   $userName                       = New-xDscResourceProperty –Name userName –Type string –Attribute Write
   $password                       = New-xDscResourceProperty –Name Password –Type PSCredential –Attribute Write
   $loadUserProfile                = New-xDscResourceProperty –Name loadUserProfile –Type string –Attribute Write -ValidateSet 'true','false'
   $setProfileEnvironment          = New-xDscResourceProperty –Name setProfileEnvironment –Type string –Attribute Write -ValidateSet 'true','false'
   $logonType                      = New-xDscResourceProperty –Name logonType –Type string –Attribute Write -ValidateSet 'LogonBatch','LogonService'
   $manualGroupMembership          = New-xDscResourceProperty –Name manualGroupMembership –Type string –Attribute Write  -ValidateSet 'true','false'
   $idleTimeout                    = New-xDscResourceProperty –Name idleTimeout –Type string –Attribute Write
   $idleTimeoutAction              = New-xDscResourceProperty –Name idleTimeoutAction –Type string –Attribute Write -ValidateSet 'Terminate','Suspend'
   $maxProcesses                   = New-xDscResourceProperty –Name maxProcesses –Type string –Attribute Write
   $shutdownTimeLimit              = New-xDscResourceProperty –Name shutdownTimeLimit –Type string –Attribute Write
   $startupTimeLimit               = New-xDscResourceProperty –Name startupTimeLimit –Type string –Attribute Write
   $pingingEnabled                 = New-xDscResourceProperty –Name pingingEnabled –Type string –Attribute Write -ValidateSet 'true','false'
   $pingInterval                   = New-xDscResourceProperty –Name pingInterval –Type string –Attribute Write
   $pingResponseTime               = New-xDscResourceProperty –Name pingResponseTime –Type string –Attribute Write
   $disallowOverlappingRotation    = New-xDscResourceProperty –Name disallowOverlappingRotation –Type string –Attribute Write -ValidateSet 'true','false'
   $disallowRotationOnConfigChange = New-xDscResourceProperty –Name disallowRotationOnConfigChange –Type string –Attribute Write -ValidateSet 'true','false'
   $logEventOnRecycle              = New-xDscResourceProperty –Name logEventOnRecycle –Type string –Attribute Write
   $memory                         = New-xDscResourceProperty –Name memory –Type string –Attribute Write
   $privateMemory                  = New-xDscResourceProperty –Name privateMemory –Type string –Attribute Write
   $requests                       = New-xDscResourceProperty –Name requests –Type string –Attribute Write
   $time                           = New-xDscResourceProperty –Name time –Type String –Attribute Write
   $schedule                       = New-xDscResourceProperty –Name schedule –Type Hashtable[] –Attribute Write
   $loadBalancerCapabilities       = New-xDscResourceProperty –Name loadBalancerCapabilities –Type string –Attribute Write -ValidateSet 'HttpLevel','TcpLevel'
   $orphanWorkerProcess            = New-xDscResourceProperty –Name orphanWorkerProcess –Type string –Attribute Write -ValidateSet 'true','false'
   $orphanActionExe                = New-xDscResourceProperty –Name orphanActionExe –Type string –Attribute Write
   $orphanActionParams             = New-xDscResourceProperty –Name orphanActionParams –Type string –Attribute Write
   $rapidFailProtection            = New-xDscResourceProperty –Name rapidFailProtection –Type string –Attribute Write -ValidateSet 'true','false'
   $rapidFailProtectionInterval    = New-xDscResourceProperty –Name rapidFailProtectionInterval –Type string –Attribute Write
   $rapidFailProtectionMaxCrashes  = New-xDscResourceProperty –Name rapidFailProtectionMaxCrashes –Type string –Attribute Write
   $autoShutdownExe                = New-xDscResourceProperty –Name autoShutdownExe –Type string –Attribute Write
   $autoShutdownParams             = New-xDscResourceProperty –Name autoShutdownParams –Type string –Attribute Write
   $limit                          = New-xDscResourceProperty –Name limit –Type string –Attribute Write
   $action                         = New-xDscResourceProperty –Name action –Type string –Attribute Write -ValidateSet 'NoAcion','KillW3wp','Throttle','ThrottleUnderLoad'
   $resetInterval                  = New-xDscResourceProperty –Name resetInterval –Type string –Attribute Write
   $smpAffinitized                 = New-xDscResourceProperty –Name smpAffinitized –Type string –Attribute Write -ValidateSet 'true','false'
   $smpProcessorAffinityMask       = New-xDscResourceProperty –Name smpProcessorAffinityMask –Type string –Attribute Write
   $smpProcessorAffinityMask2      = New-xDscResourceProperty –Name smpProcessorAffinityMask2 –Type string –Attribute Write
   $processorGroup                 = New-xDscResourceProperty –Name processorGroup –Type string –Attribute Write
   $numaNodeAssignment             = New-xDscResourceProperty –Name numaNodeAssignment –Type string –Attribute Write -ValidateSet 'MostAvailableMemory','WindowsScheduling'
   $numaNodeAffinityMode           = New-xDscResourceProperty –Name numaNodeAffinityMode –Type string –Attribute Write -ValidateSet 'Soft','Hard'

#array to hold our properties
$xDscProperties [email protected](
       $Ensure
       $name,
       $queueLength,
       $autoStart,
       $enable32BitAppOnWin64,
       $managedRuntimeVersion,
       $managedRuntimeLoader,
       $enableConfigurationOverride,
       $managedPipelineMode,
       $CLRConfigFile,
       $passAnonymousToken,
       $startMode,
       $identityType,
       $userName,
       $password,
       $loadUserProfile,
       $setProfileEnvironment,
       $logonType,
       $manualGroupMembership,
       $idleTimeout,
       $idleTimeoutAction,
       $maxProcesses,
       $shutdownTimeLimit,
       $startupTimeLimit,
       $pingingEnabled,
       $pingInterval,
       $pingResponseTime,
       $disallowOverlappingRotation,
       $disallowRotationOnConfigChange,
       $logEventOnRecycle,
       $memory,
       $privateMemory,
       $requests,
       $time,
       $schedule,
       $loadBalancerCapabilities,
       $orphanWorkerProcess,
       $orphanActionExe,
       $orphanActionParams,
       $rapidFailProtection,
       $rapidFailProtectionInterval,
       $rapidFailProtectionMaxCrashes,
       $autoShutdownExe,
       $autoShutdownParams,
       $limit,
       $action,
       $resetInterval,
       $smpAffinitized,
       $smpProcessorAffinityMask,
       $smpProcessorAffinityMask2,
       $processorGroup,
       $numaNodeAssignment,
       $numaNodeAffinityMode      
    )

# Create resource that will be creating our application pool 
New-xDscResource -Name RafPe_cWebAppPool`
                 -FriendlyName cWebAppPool`
                 -ModuleName cWebAdmin`
                 -Path 'C:\Program Files\WindowsPowerShell\Modules' `
                 -Property $xDscProperties -Verbose

 

So what happened here ? We have created a lot of DSC resource properties and then used array to hold those values. Why array ? Well because then its simple to pass it into the command which has created the resource for us. New-xDscResource 

You may noticed that I have used RafPe_cWebAppPool as the name. This is because I’m not the only one creating names and they for obvious reasons cannot be the same. Therefore further as parameter we have friendly name which I set to be cWebAppPool. Next is quite important as it is our module name which I have decided to be cWebAdmin as purpose of this module is to manage not only app Pool but much more on IIS webservers . Lastly its path (which I use the default ones for modules ) and finally our array of properties for creation.

For purposes of better visibility I have made sure there is the verbose switch added.

Once you execute this you should see output similar to the following :

2015-08-13_22h41_02

 

 

Prep work for resource functions

Now comes the most interesting part. Remember the important trio of functions I mentioned ? Get/Set/Test ? This will be the time to start coding them to do the really heavy lifting for us.

Now since I really like to simplify my life we will use a wrapper function to get and set settings in AppPool. Reason for doing this will be clearly visible later when we cut down the number of unnecessary code really significantly.

As usual the most up to date function you will find on GitHub

# Function which allows for quick set/get of app pool property - make sure you have the newest one 🙂
# available @  https://gist.github.com/RafPe/77d2ff28f7a0014bf0f1
function Invoke-AppPoolSetting
{

    param
    (    
        [string]$appPoolName,
        [Parameter(Mandatory=$true)]
        [ValidateNotNullOrEmpty()]
        $propertyName,
        [Parameter(Mandatory=$true)]
        [ValidateSet('get','set')]
        [string]$action,
        $value                
    )

    #Mapping of namespace (works on IIS 8.5)
    $NamespaceMapping = @{
       name                        = 'system.applicationHost/applicationPools/{0}'
       queueLength                 = 'system.applicationHost/applicationPools/{0}';
       autoStart                   = 'system.applicationHost/applicationPools/{0}';
       enable32BitAppOnWin64       = 'system.applicationHost/applicationPools/{0}';
       managedRuntimeVersion       = 'system.applicationHost/applicationPools/{0}';
       managedRuntimeLoader        = 'system.applicationHost/applicationPools/{0}';
       enableConfigurationOverride = 'system.applicationHost/applicationPools/{0}';
       managedPipelineMode         = 'system.applicationHost/applicationPools/{0}';
       CLRConfigFile               = 'system.applicationHost/applicationPools/{0}';
       passAnonymousToken          = 'system.applicationHost/applicationPools/{0}';
       startMode                   = 'system.applicationHost/applicationPools/{0}';
       identityType          = 'system.applicationHost/applicationPools/{0}/processModel';
       userName              = 'system.applicationHost/applicationPools/{0}/processModel';
       password              = 'system.applicationHost/applicationPools/{0}/processModel';
       loadUserProfile       = 'system.applicationHost/applicationPools/{0}/processModel';
       setProfileEnvironment = 'system.applicationHost/applicationPools/{0}/processModel';
       logonType             = 'system.applicationHost/applicationPools/{0}/processModel';
       manualGroupMembership = 'system.applicationHost/applicationPools/{0}/processModel';
       idleTimeout           = 'system.applicationHost/applicationPools/{0}/processModel';
       idleTimeoutAction     = 'system.applicationHost/applicationPools/{0}/processModel';
       maxProcesses          = 'system.applicationHost/applicationPools/{0}/processModel';
       shutdownTimeLimit     = 'system.applicationHost/applicationPools/{0}/processModel';
       startupTimeLimit      = 'system.applicationHost/applicationPools/{0}/processModel';
       pingingEnabled        = 'system.applicationHost/applicationPools/{0}/processModel';
       pingInterval          = 'system.applicationHost/applicationPools/{0}/processModel';
       pingResponseTime      = 'system.applicationHost/applicationPools/{0}/processModel';
       disallowOverlappingRotation    = 'system.applicationHost/applicationPools/{0}/recycling';
       disallowRotationOnConfigChange = 'system.applicationHost/applicationPools/{0}/recycling';
       logEventOnRecycle              = 'system.applicationHost/applicationPools/{0}/recycling';
       memory                         = 'system.applicationHost/applicationPools/{0}/recycling/periodicRestart';
       privateMemory                  = 'system.applicationHost/applicationPools/{0}/recycling/periodicRestart';
       requests                       = 'system.applicationHost/applicationPools/{0}/recycling/periodicRestart';
       time                           = 'system.applicationHost/applicationPools/{0}/recycling/periodicRestart';
       schedule                       = 'system.applicationHost/applicationPools/{0}/recycling/periodicRestart/schedule';
       loadBalancerCapabilities      = 'system.applicationHost/applicationPools/{0}/failure';
       orphanWorkerProcess           = 'system.applicationHost/applicationPools/{0}/failure';
       orphanActionExe               = 'system.applicationHost/applicationPools/{0}/failure';
       orphanActionParams            = 'system.applicationHost/applicationPools/{0}/failure';
       rapidFailProtection           = 'system.applicationHost/applicationPools/{0}/failure';
       rapidFailProtectionInterval   = 'system.applicationHost/applicationPools/{0}/failure';
       rapidFailProtectionMaxCrashes = 'system.applicationHost/applicationPools/{0}/failure';
       autoShutdownExe               = 'system.applicationHost/applicationPools/{0}/failure';
       autoShutdownParams            = 'system.applicationHost/applicationPools/{0}/failure';
       limit                     = 'system.applicationHost/applicationPools/{0}/cpu';
       action                    = 'system.applicationHost/applicationPools/{0}/cpu';
       resetInterval             = 'system.applicationHost/applicationPools/{0}/cpu';
       smpAffinitized            = 'system.applicationHost/applicationPools/{0}/cpu';
       smpProcessorAffinityMask  = 'system.applicationHost/applicationPools/{0}/cpu';
       smpProcessorAffinityMask2 = 'system.applicationHost/applicationPools/{0}/cpu';
       processorGroup            = 'system.applicationHost/applicationPools/{0}/cpu';
       numaNodeAssignment        = 'system.applicationHost/applicationPools/{0}/cpu';
       numaNodeAffinityMode      = 'system.applicationHost/applicationPools/{0}/cpu';
    }

    # Create target app pool name 
    if( [string]::IsNullOrEmpty($appPoolName) -or $appPoolName -eq 'applicationPoolDefaults' ) { $targetAppName = 'applicationPoolDefaults' } else { $targetAppName = [string]::Format("add[@name='{0}']",$appPoolName ) }
    
    switch ($action)
    {
      'get'        { 

                        Write-Debug "using $targetAppName as target name"
                        # gets value
                        
                        try
                        {
                          Write-Debug "Requesting property $propertyName value for appPool $appPoolName"
                          $res =  (Get-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST'  -filter $( $NamespaceMapping[ $propertyName ] -f $targetAppName ) -name $propertyName)
                            
                          Write-Debug "property is type of $($res.GetType().Name)"

                          #We need to distinguish from simple value type to complex value types
                          if ( $res.GetType().Name -eq 'ConfigurationAttribute')
                          {

                            return $res.Value.ToString()
                          }
                          else
                          {

                           
                            return $res.ToString()
                          }

                        }
                        catch
                        {
                            Throw "Could not retrieve property $propertyName for appPool $Name"
                        }
                        
                        
                   }
      
      'set'        { 
                       
                       if($null -eq $value)
                       {
                            Throw 'Please ensure that value is specified for set and is not NULL'
                       }

                        try
                        {
                          Write-Debug "Setting  property $propertyName with value $value for appPool $Name"
                          Set-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST'  -filter $( $NamespaceMapping[ $propertyName ] -f $targetAppName ) -name $propertyName -Value $value
                        
                        }
                        catch
                        {
                            Throw "Could not set property $propertyName with value $value for appPool $Name"
                        }

                       

                   }
    }
}

 

What does this allows me to do ? Well quite simple – in one cmdlet based on dynamic paramater name/value pair (or just parameter name) I can get or set a value for application pool! I think this is quite useful. So how this cmdlet is being used ?

Invoke-AppPoolSetting -propertyName disallowRotationOnConfigChange -action get;

The above quite easily gets me exactly the property I’m after. And now also the setting of property is quite intuitive. You just need to flip the correct action parameter and voilla – you are done for settign and getting in professional way.

 

Get-Resource

Its time to dive into functons that are responsible for actual heavy lifting of the resources. We will first focus on the Get function. It is quite simple as it just gets all resource properties which we have defined while creating this resource.  As usual the most up to date function wll be available on GitHub

function Get-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        [parameter(Mandatory = $true)]
        [System.String]
        $Name
    )

    #Remove debug from params
    $psboundparameters.Remove('Debug') | Out-Null
    $psboundparameters.Remove('Verbose') | Out-Null

    #TODO - schedule fix up 
    $psboundparameters.Remove('schedule') | Out-Null

    #Write-Verbose "Use this cmdlet to deliver information about command processing."

    #Write-Debug "Use this cmdlet to write debug information while troubleshooting."

    Write-Verbose 'Checking for app pool specified credentials'
    $appPoolUserName = Invoke-AppPoolSetting -propertyName userName -action get

    if($appPoolUserName)
    {
                Write-Verbose 'app pool has specific identity - creating PSCredential object'

                $AppPoolPassword = Invoke-AppPoolSetting -propertyName password -action get | ConvertTo-SecureString -AsPlainText -Force
                $AppPoolCred     = new-object -typename System.Management.Automation.PSCredential -argumentlist $appPoolUserName,$AppPoolPassword
    }
    else
    {
                Write-Verbose 'app pool does not have specific identity - nothing to do here'
                $AppPoolCred =$null
    }

    
    $returnValue = @{
        Name                          = Invoke-AppPoolSetting -propertyName Name -action get;
        queueLength                   = Invoke-AppPoolSetting -propertyName queueLength -action get;
        autoStart                     = Invoke-AppPoolSetting -propertyName autoStart -action get;
        enable32BitAppOnWin64         = Invoke-AppPoolSetting -propertyName enable32BitAppOnWin64 -action get;
        managedRuntimeVersion         = Invoke-AppPoolSetting -propertyName managedRuntimeVersion -action get;
        managedRuntimeLoader          = Invoke-AppPoolSetting -propertyName managedRuntimeLoader -action get;
        enableConfigurationOverride   = Invoke-AppPoolSetting -propertyName enableConfigurationOverride -action get;
        managedPipelineMode           = Invoke-AppPoolSetting -propertyName managedPipelineMode -action get;
        CLRConfigFile                 = Invoke-AppPoolSetting -propertyName CLRConfigFile -action get;
        passAnonymousToken            = Invoke-AppPoolSetting -propertyName passAnonymousToken -action get;
        startMode                     = Invoke-AppPoolSetting -propertyName startMode -action get;
        identityType                  = Invoke-AppPoolSetting -propertyName identityType -action get;
        userName                      = $appPoolUserName;
        Password                      = $AppPoolPassword;
        loadUserProfile               = Invoke-AppPoolSetting -propertyName loadUserProfile -action get;
        setProfileEnvironment         = Invoke-AppPoolSetting -propertyName setProfileEnvironment -action get;
        logonType                     = Invoke-AppPoolSetting -propertyName logonType -action get;
        manualGroupMembership         = Invoke-AppPoolSetting -propertyName manualGroupMembership -action get;
        idleTimeout                   = Invoke-AppPoolSetting -propertyName idleTimeout -action get;
        idleTimeoutAction             = Invoke-AppPoolSetting -propertyName idleTimeoutAction -action get;
        maxProcesses                  = Invoke-AppPoolSetting -propertyName maxProcesses -action get;
        shutdownTimeLimit             = Invoke-AppPoolSetting -propertyName shutdownTimeLimit -action get;
        startupTimeLimit              = Invoke-AppPoolSetting -propertyName startupTimeLimit -action get;
        pingingEnabled                = Invoke-AppPoolSetting -propertyName pingingEnabled -action get;
        pingInterval                  = Invoke-AppPoolSetting -propertyName pingInterval -action get;
        pingResponseTime              = Invoke-AppPoolSetting -propertyName pingResponseTime -action get;
        disallowOverlappingRotation   = Invoke-AppPoolSetting -propertyName disallowOverlappingRotation -action get;
        disallowRotationOnConfigChange = Invoke-AppPoolSetting -propertyName disallowRotationOnConfigChange -action get;
        logEventOnRecycle             = Invoke-AppPoolSetting -propertyName logEventOnRecycle -action get;
        memory                        = Invoke-AppPoolSetting -propertyName memory -action get;
        privateMemory                 = Invoke-AppPoolSetting -propertyName privateMemory -action get;
        requests                      = Invoke-AppPoolSetting -propertyName requests -action get;
        time                          = Invoke-AppPoolSetting -propertyName time -action get;
        schedule                      = '';# TODO - investigate schedule setup Invoke-AppPoolSetting -propertyName schedule -action get;
        loadBalancerCapabilities      = Invoke-AppPoolSetting -propertyName loadBalancerCapabilities -action get;
        orphanWorkerProcess           = Invoke-AppPoolSetting -propertyName orphanWorkerProcess -action get;
        orphanActionExe               = Invoke-AppPoolSetting -propertyName orphanActionExe -action get;
        orphanActionParams            = Invoke-AppPoolSetting -propertyName orphanActionParams -action get;
        rapidFailProtection           = Invoke-AppPoolSetting -propertyName rapidFailProtection -action get;
        rapidFailProtectionInterval   = Invoke-AppPoolSetting -propertyName rapidFailProtectionInterval -action get;
        rapidFailProtectionMaxCrashes = Invoke-AppPoolSetting -propertyName rapidFailProtectionMaxCrashes -action get;
        autoShutdownExe               = Invoke-AppPoolSetting -propertyName autoShutdownExe -action get;
        autoShutdownParams            = Invoke-AppPoolSetting -propertyName autoShutdownParams -action get;
        limit                         = Invoke-AppPoolSetting -propertyName limit -action get;
        action                        = Invoke-AppPoolSetting -propertyName action -action get;
        resetInterval                 = Invoke-AppPoolSetting -propertyName resetInterval -action get;
        smpAffinitized                = Invoke-AppPoolSetting -propertyName smpAffinitized -action get;
        smpProcessorAffinityMask      = Invoke-AppPoolSetting -propertyName smpProcessorAffinityMask -action get;
        smpProcessorAffinityMask2     = Invoke-AppPoolSetting -propertyName smpProcessorAffinityMask2 -action get;
        processorGroup                = Invoke-AppPoolSetting -propertyName processorGroup -action get;
        numaNodeAssignment            = Invoke-AppPoolSetting -propertyName numaNodeAssignment -action get;
        numaNodeAffinityMode          = Invoke-AppPoolSetting -propertyName numaNodeAffinityMode -action get;
    }

    $returnValue

}

 

Test-resource

This function is as the name says 😀 responsible for testing property/value So without any further delays here is the function

function Test-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Boolean])]
    param
    (
        [parameter(Mandatory = $true)]
        [System.String]
        $Name,

        [System.String]
        $queueLength,

        [System.String]
        $autoStart,

        [ValidateSet('true','false')]
        [System.String]
        $enable32BitAppOnWin64,

        [ValidateSet('v4.0','v2.0','')]
        [System.String]
        $managedRuntimeVersion,

        [System.String]
        $managedRuntimeLoader,

        [ValidateSet('true','false')]
        [System.String]
        $enableConfigurationOverride,

        [ValidateSet('Integrated','Classic')]
        [System.String]
        $managedPipelineMode,

        [System.String]
        $CLRConfigFile,

        [ValidateSet('true','false')]
        [System.String]
        $passAnonymousToken,

        [ValidateSet('AlwaysRunning','OnDemand')]
        [System.String]
        $startMode,

        [ValidateSet('ApplicationPoolIdentity','LocalSystem','LocalService','NetworkService','SpecificUser')]
        [System.String]
        $identityType,

        [System.String]
        $userName,

        [System.Management.Automation.PSCredential]
        $Password,

        [ValidateSet('true','false')]
        [System.String]
        $loadUserProfile,

        [ValidateSet('true','false')]
        [System.String]
        $setProfileEnvironment,

        [ValidateSet('LogonBatch','LogonService')]
        [System.String]
        $logonType,

        [ValidateSet('true','false')]
        [System.String]
        $manualGroupMembership,

        [System.String]
        $idleTimeout,

        [ValidateSet('Terminate','Suspend')]
        [System.String]
        $idleTimeoutAction,

        [System.String]
        $maxProcesses,

        [System.String]
        $shutdownTimeLimit,

        [System.String]
        $startupTimeLimit,

        [ValidateSet('true','false')]
        [System.String]
        $pingingEnabled,

        [System.String]
        $pingInterval,

        [System.String]
        $pingResponseTime,

        [ValidateSet('true','false')]
        [System.String]
        $disallowOverlappingRotation,

        [ValidateSet('true','false')]
        [System.String]
        $disallowRotationOnConfigChange,

        [System.String]
        $logEventOnRecycle,

        [System.String]
        $memory,

        [System.String]
        $privateMemory,

        [System.String]
        $requests,

        [System.String]
        $time,

        [Microsoft.Management.Infrastructure.CimInstance[]]
        $schedule,

        [ValidateSet('HttpLevel','TcpLevel')]
        [System.String]
        $loadBalancerCapabilities,

        [ValidateSet('true','false')]
        [System.String]
        $orphanWorkerProcess,

        [System.String]
        $orphanActionExe,

        [System.String]
        $orphanActionParams,

        [ValidateSet('true','false')]
        [System.String]
        $rapidFailProtection,

        [System.String]
        $rapidFailProtectionInterval,

        [System.String]
        $rapidFailProtectionMaxCrashes,

        [System.String]
        $autoShutdownExe,

        [System.String]
        $autoShutdownParams,

        [System.String]
        $limit,

        [ValidateSet('NoAcion','KillW3wp','Throttle','ThrottleUnderLoad')]
        [System.String]
        $action,

        [System.String]
        $resetInterval,

        [ValidateSet('true','false')]
        [System.String]
        $smpAffinitized,

        [System.String]
        $smpProcessorAffinityMask,

        [System.String]
        $smpProcessorAffinityMask2,

        [System.String]
        $processorGroup,

        [ValidateSet('MostAvailableMemory','WindowsScheduling')]
        [System.String]
        $numaNodeAssignment,

        [ValidateSet('Soft','Hard')]
        [System.String]
        $numaNodeAffinityMode
    )

    #Remove debug from params
    $psboundparameters.Remove('Debug') | Out-Null
    $psboundparameters.Remove('Verbose') | Out-Null

    #TODO - schedule fix up 
    $psboundparameters.Remove('schedule') | Out-Null

    $DesiredConfigurationMatch = $true

    # Check if WebAdministration module is present for IIS cmdlets
    if(!(Get-Module -ListAvailable -Name WebAdministration))
    {
        Throw 'Please ensure that WebAdministration module is installed.'
    }

    #Enumrate all params and info if necessary 
    foreach($psbp in $PSBoundParameters.GetEnumerator())
    {
          Write-Debug "xChecking value for $($psbp.Key)"

          $currValue = (Invoke-AppPoolSetting -propertyName $psbp.Key -action get)
          Write-Debug "Current value type :  $($currValue.GetType().Name)"
          Write-Debug "DSC type :  $($($psbp.Value).GetType().Name)"
          
          # We get current status and compare it with desired state  
          if( $currValue -ne $psbp.Value )
          {
                Write-Debug "Value for $( $psbp.Key ) [ $currValue ]  does not match the desired state [$( $psbp.Value )]"

                $DesiredConfigurationMatch = $false
          }
          else
          {
                 Write-Debug "Value for $( $psbp.Key ) [ $currValue ]  does match the desired state [$( $psbp.Value )]"
          }

    }

    return $DesiredConfigurationMatch
}

 

There are couple of points in this function wich are worth a bit of explanation. As I have seen several implementation of this function where suddenly you have ~ 150 conditional statements i.e. (if ($x) {} else {} ) and so on … so on and so on….. come on! Of course you can do better and optimize your code against redundant repetitions. Think always here about the moing parts … what is shared … what is common … what can you use …. 😀

So what can we use here ? Well something like $PsBoundParameters. If you would ask what are those asking the rigth places says … “It’s a hashtable containing the parameters that were bound and what values were bound to them” (source of this info )

We start by etablishing iteration of all available parameters

foreach($psbp in $PSBoundParameters.GetEnumerator())
{
    // ......

This will give us all parameters that have been passed to this function. Thats already great first step. So since this is testing function we need to start testing parameters passed . First we get current value using our customized function which we discussed before

$currValue = (Invoke-AppPoolSetting -propertyName $psbp.Key -action get)

This will retrieve current value for our specified setting. $psbp.Key will be holding name of parameter passes i.e. autostart , name etc.

Having that value we will compare it with our desired state. We do that by comparing $currValue with $psbp.Value (which is value passed as parameter)

# We get current status and compare it with desired state  
          if( $currValue -ne $psbp.Value )
          {
                Write-Debug "Value for $( $psbp.Key ) [ $currValue ]  does not match the desired state [$( $psbp.Value )]"

                $DesiredConfigurationMatch = $false
          }
          else
          {
                 Write-Debug "Value for $( $psbp.Key ) [ $currValue ]  does match the desired state [$( $psbp.Value )]"
          }

The last thing that is left is to return value which determines if we need to act. This is done by returning $DesiredConfigurationMatch

Ok so not much left to first success 😀 The remaining one is the one that does the work for us when we have drift from required configuration

Set-resource

We will apply similar approach as with our function above. Code looks following

function Set-TargetResource
{
    [CmdletBinding()]
    param
    (
        [parameter(Mandatory = $true)]
        [System.String]
        $Name,

        [System.String]
        $queueLength,

        [System.String]
        $autoStart,

        [ValidateSet('true','false')]
        [System.String]
        $enable32BitAppOnWin64,

        [ValidateSet('v4.0','v2.0','')]
        [System.String]
        $managedRuntimeVersion,

        [System.String]
        $managedRuntimeLoader,

        [ValidateSet('true','false')]
        [System.String]
        $enableConfigurationOverride,

        [ValidateSet('Integrated','Classic')]
        [System.String]
        $managedPipelineMode,

        [System.String]
        $CLRConfigFile,

        [ValidateSet('true','false')]
        [System.String]
        $passAnonymousToken,

        [ValidateSet('AlwaysRunning','OnDemand')]
        [System.String]
        $startMode,

        [ValidateSet('ApplicationPoolIdentity','LocalSystem','LocalService','NetworkService','SpecificUser')]
        [System.String]
        $identityType,

        [System.String]
        $userName,

        [System.Management.Automation.PSCredential]
        $Password,

        [ValidateSet('true','false')]
        [System.String]
        $loadUserProfile,

        [ValidateSet('true','false')]
        [System.String]
        $setProfileEnvironment,

        [ValidateSet('LogonBatch','LogonService')]
        [System.String]
        $logonType,

        [ValidateSet('true','false')]
        [System.String]
        $manualGroupMembership,

        [System.String]
        $idleTimeout,

        [ValidateSet('Terminate','Suspend')]
        [System.String]
        $idleTimeoutAction,

        [System.String]
        $maxProcesses,

        [System.String]
        $shutdownTimeLimit,

        [System.String]
        $startupTimeLimit,

        [ValidateSet('true','false')]
        [System.String]
        $pingingEnabled,

        [System.String]
        $pingInterval,

        [System.String]
        $pingResponseTime,

        [ValidateSet('true','false')]
        [System.String]
        $disallowOverlappingRotation,

        [ValidateSet('true','false')]
        [System.String]
        $disallowRotationOnConfigChange,

        [System.String]
        $logEventOnRecycle,

        [System.String]
        $memory,

        [System.String]
        $privateMemory,

        [System.String]
        $requests,

        [System.String]
        $time,

        [Microsoft.Management.Infrastructure.CimInstance[]]
        $schedule,

        [ValidateSet('HttpLevel','TcpLevel')]
        [System.String]
        $loadBalancerCapabilities,

        [ValidateSet('true','false')]
        [System.String]
        $orphanWorkerProcess,

        [System.String]
        $orphanActionExe,

        [System.String]
        $orphanActionParams,

        [ValidateSet('true','false')]
        [System.String]
        $rapidFailProtection,

        [System.String]
        $rapidFailProtectionInterval,

        [System.String]
        $rapidFailProtectionMaxCrashes,

        [System.String]
        $autoShutdownExe,

        [System.String]
        $autoShutdownParams,

        [System.String]
        $limit,

        [ValidateSet('NoAcion','KillW3wp','Throttle','ThrottleUnderLoad')]
        [System.String]
        $action,

        [System.String]
        $resetInterval,

        [ValidateSet('true','false')]
        [System.String]
        $smpAffinitized,

        [System.String]
        $smpProcessorAffinityMask,

        [System.String]
        $smpProcessorAffinityMask2,

        [System.String]
        $processorGroup,

        [ValidateSet('MostAvailableMemory','WindowsScheduling')]
        [System.String]
        $numaNodeAssignment,

        [ValidateSet('Soft','Hard')]
        [System.String]
        $numaNodeAffinityMode
    )

    #Remove debug from params
    $psboundparameters.Remove('Debug') | Out-Null
    $psboundparameters.Remove('Verbose') | Out-Null

    #TODO - schedule fix up 
    $psboundparameters.Remove('schedule') | Out-Null

    # Check if WebAdministration module is present for IIS cmdlets
    if(!(Get-Module -ListAvailable -Name WebAdministration))
        {
            Throw 'Please ensure that WebAdministration module is installed.'
        }

    #Enumrate all params and act if necessary 
    foreach($psbp in $PSBoundParameters.GetEnumerator())
    {
          Write-Debug "Checking value for $($psbp.Key)"
          
          # We get current status and compare it with desired state  
          if( (Invoke-AppPoolSetting -propertyName $psbp.Key -action get) -ne $psbp.Value )
          {
                Write-Verbose "Setting value for $( $psbp.Key ) to $( $psbp.Value )"
                Invoke-AppPoolSetting -propertyName $psbp.Key -value $psbp.Value -action set
          }

    }

    # Our dsc does not require reboot
    $global:DSCMachineStatus = 0


}

 

The whole magic is hidden in this pice of the code

          # We get current status and compare it with desired state  
          if( (Invoke-AppPoolSetting -propertyName $psbp.Key -action get) -ne $psbp.Value )
          {
                Write-Verbose "Setting value for $( $psbp.Key ) to $( $psbp.Value )"
                Invoke-AppPoolSetting -propertyName $psbp.Key -value $psbp.Value -action set
          }

In the ‘if’ statement we invoke get of setting (with use of our special function 🙂 ) and compare it with value passed. If there is mismatch we set appropiate value.

 

And that would be it for creating resource 🙂

 

Finally first testing 😀

So after all of that effort we have been through we can go ahead and give it a go 😀 I prepared a small example (which accordingly to best practices is part of the module )

This is what we will be playing with

2015-08-16_23h13_48

 

So lets configure it in our DSC config….

configuration Config_AppPoolDefaaults
{
    param
    (
        # Target nodes to apply the configuration
        [string[]]$NodeName = 'localhost'
    )

    # Import the module that defines custom resources
    Import-DscResource -ModuleName 'cWebAdmin'
    Import-DscResource –ModuleName ’PSDesiredStateConfiguration’

    Node $NodeName
    {
       
        # still pointing to defaults - to be changed 
        cWebAppPoolDefaults ConfigureAppPoolDefaults 
        {
            Name                =  'applicationPoolDefaults'        # by pecyfying 'applicationPoolDefaults' as name we show we want to act on default  
            managedPipelineMode =  'Integrated'            
            autoStart           =  'true'
            startMode           =  'AlwaysRunning'
        }
           
    }
}

 

Once invoked you will see similar output

PS C:\temp> Config_AppPoolDefaaults


    Directory: C:\temp\Config_AppPoolDefaaults


Mode                LastWriteTime         Length Name                          
----                -------------         ------ ----                          
-a----        16-8-2015     23:20           2142 localhost.mof                 

 

Then its the time to make that big cmdlet come to alive 😀 ….

 

Amongst many other reults (which I dont show here for clear of this post ) we see i.e.

2015-08-16_23h28_29

And later when setting is not as we wanted it … we see correction

2015-08-16_23h31_30

 

 

Results after applying in IIS ….

2015-08-16_23h32_24

 

 

 

Summary

I think this is great – power of DSC is really out there and I think we should be reaching out to a great tool like that! If you would have any comments or suggestions as usual please leave a comment or participate in this project on GitHub

In the next post we will be focusing on getting this up to level where you can drop it on production servers.  Stay tuned!

 

 

0

Powershell – DSC checklist

As you remember we are in the middle of the series for DSC module creation. I maybe should have mentioned this before but better now than never.  What I’m talking about … well its all about good practice within DSC. Some of them we do apply and some we will apply in our DSC series.

As it is good to have it around I decided to do a repost . Source from http://blogs.msdn.com/b/powershell/archive/2014/11/18/powershell-dsc-resource-design-and-testing-checklist.aspx

1       Resource module contains .psd1 file and schema.mof for every resource

2       Resource and schema are correct and have been verified using DscResourceDesigner cmdlets

3       Resource loads without errors

4       Resource is idempotent in the positive case

5       User modification scenario was tested

6       Get-TargetResource functionality was verified using Get-DscConfiguration

7       Resource was verified by calling Get/Set/Test-TargetResource functions directly

8       Resource was verified End to End using Start-DscConfiguration

9       Resource behaves correctly on all DSC supported platforms (or returns a specific error otherwise)

10     Resource functionality was verified on Windows Client (if applicable)

11     Get-DSCResource lists the resource

12     Resource module contains examples

13     Error messages are easy to understand and help users solve problems

14     Log messages are easy to understand and informative (including –verbose, –debug and ETW logs)

15     Resource implementation does not contain hardcoded paths

16     Resource implementation does not contain user information

17     Resource was tested with valid/invalid credentials

18     Resource is not using cmdlets requiring interactive input

19     Resource functionality was thoroughly tested

20     Best practice: Resource module contains Tests folder with ResourceDesignerTests.ps1 script

21     Best practice: Resource folder contains resource designer script for generating schema

22     Best practice: Resource supports -whatif

0

PowerShell – Creating DSC module – Part 2

Hey ,

Without any further delays we will continue our excercise to write yp DSC module containing multiple resources. As this is multi-part post you might want to jump back to first post to read up on preparations and considerations.

 

Objectives for this post:

In this particular post we will focus on creating DSC resource properties and modifying out root module manifest.  Source code in ps1 format for what we will be doing today is available as usual 🙂 on GitHub  ( https://github.com/RafPe/cWebAdmin/blob/master/src/createDscResources.ps1 ) so if you would like to help or have feedback or suggestions leave a comment or just fork the script and request a pull 😀

If you are new to this series of post I’m aiming to get fully operational webapp Pool and website admin DSC module (at the moment of writing this post it will support only IIS 8.5 ). If you would say “Hey! But there is already one from MS available even on GitHub! So why reinvent the wheel ?” then my answer would be ‘The ones available do not perform scope of configurations I want to do – therefore I’m creating one to fullfuill my technical needs and on the other hand I get a nice tech excercise! ‘

 

Investigate your target resource properties:

Let’s go ahead and see what’s available for us. As usual there are multipe ways to achieve your goal 😀 its all about selecting the optimal one. As in majority cases you could go ahead and investigate GUI to see which ones are available for you. Something in lines of :

2015-08-09_18h10_51

 

Hmmmm … but really – how much time will it take you to complete list of all available properties ? So lets go ahead and do it a bit differently.

$props = Get-Item IIS:\AppPools\<YourAppPoolNam> | Get-Member -MemberType NoteProperty

That gives you more less output similar to the following one :

2015-08-09_18h15_19

 

So is that all ? 🙂 Of course it isnt – we are missing quite a lot. The remaining properties are hidden in child elements collections. We get to them by calling :

(Get-Item IIS:\AppPools\<YourAppPoolName>).ChildElements

And that gives you the following output :

2015-08-09_18h17_43

 

And you access the properties of each collection by calling

(Get-Item IIS:\AppPools\<YourAppPoolName>).ChildElements['processmodel'].Attributes | select Name,TypeName

and our output will look similar to the following one :

2015-08-09_18h22_12

 

 

Fine 🙂 we have our resources and more less we know their types (keep in mind that some of int types here – within GUI are enums )

 

Get me the resource!

Ok – so you are hungry for coding 😀 I totally udnerstand – So let’s discuss cmdlet that will be playing main role here for us : which is New-xDscResourceProperty.

This cmdlet has couple of properties which we need to discuss. Lets take a look on example of usage :

$managedRuntimeVersion          = New-xDscResourceProperty –Name managedRuntimeVersion –Type string –Attribute Write -ValidateSet "v4.0","v2.0",""

As you can see we specify couple of important switches :

  1. Name : I think that this will be self explanatory 🙂 What you need to keep in mind that single DSC resource CANNOT HAVE 2 properties with the same name (but you can imagine why 🙂 )
  2. Type This defines what type is the property we will be working with
  3. Attribute :
    [ Key ]     : 
    on a property signals that the property uniquely identifies the resource
    [ Write ] : means we can assign value in our configuration
    [ Read ]  : indicates that property cannot be changed , neither we can assign value to it
  4. Description : Allows you to describe property
  5. Values and ValuesMap : restricts possible property values to specified in ValuesMap

 

It’s coding time 😀

 

Since now you know how to go about this – lets go ahead and create our resources properties and finally our resource. The decision how to tackle all properties and creating each one I leave up to you. At the moment of writing this post in series my script have had defined all of them (however this could have changed 🙂 )

Since I want to create multiple resource properties I define them as following :

   $Ensure                         = New-xDscResourceProperty –Name autoStart –Type String –Attribute Write
   $enable32BitAppOnWin64          = New-xDscResourceProperty –Name enable32BitAppOnWin64 –Type string –Attribute Write -ValidateSet "true","false"
   $managedRuntimeVersion          = New-xDscResourceProperty –Name managedRuntimeVersion –Type string –Attribute Write -ValidateSet "v4.0","v2.0",""
   $managedRuntimeLoader           = New-xDscResourceProperty –Name managedRuntimeLoader –Type string –Attribute Write

# -------------- Rest is removed for clear of this example 
# -------------- script is available @ https://github.com/RafPe/cWebAdmin/blob/master/src/createDscResources.ps1

 

Next to ease assigning them into a new resource I create an array

$xDscProperties [email protected](
       $name,
       # -------------------------- Removed for visibility
       $numaNodeAffinityMode      
    )

 

And once all of that is done we can go ahead and finally create our new resource! In my case this is resource to manage WebApp pool default settings.

# Create resource that will be defining defaults for application pool 
New-xDscResource -Name RafPe_cWebAppPoolDefaults`
                 -FriendlyName cWebAppPoolDefaults`
                 -ModuleName cWebAdmin`
                 -Path 'C:\Program Files\WindowsPowerShell\Modules' `
                 -Property $xDscProperties  -Verbose

As you can see here I’m prefixing the resource name with RafPe_ and I’m doing this because a lot of other people could come up with same name. Altough FriendlyName I’m choosing to be cWebAppPoolDefaults as thats the way I want resource to show up. Next we define our root module name which in my case is cWebAdminFollowed by Path which in this case points to default modules folder. And of course the most important – I specify our resource properties which we have just defined a moment ago.

Once you are happy with your module just hit enter! And after couple of seconds your new module should be ready and good to go!

You should now have your module already available for import .

2015-08-09_19h02_15

 

Modify root DSC module manifest:

Whats now left – we need to modify module manifest. Easiest (and a lot of ppl do it ) is to copy one of already existsing ones and just changed it a bit. What is extremly important is to generate own new GUID 

Module manifest for root module we are working with looks following :

#
# Module manifest for module 'cWebAdmin'
# Author RafPe

@{

# Version number of this module.
ModuleVersion = '1.0'

# ID used to uniquely identify this module
GUID = 'f3e1b30a-9292-4ca3-a1f1-572bd64cf460'

# Author of this module
Author = 'RafPe'

# Company or vendor of this module
CompanyName = 'RafPe'

# Copyright statement for this module
Copyright = '(c) 2015 RafPe. All rights reserved.'

# Description of the functionality provided by this module
Description = 'Module with DSC Resources for Web Administration'

# Minimum version of the Windows PowerShell engine required by this module
PowerShellVersion = '4.0'

# Minimum version of the common language runtime (CLR) required by this module
CLRVersion = '4.0'

# Private data to pass to the module specified in RootModule/ModuleToProcess. This may also contain a PSData hashtable with additional module metadata used by PowerShell.
PrivateData = @{

    PSData = @{

    # A URL to the license for this module.
    LicenseUri = 'https://rafpe.ninja'

    # A URL to the main website for this project.
    ProjectUri = 'https://rafpe.ninja'

    } # End of PSData hashtable

} # End of PrivateData hashtable

# Functions to export from this module
FunctionsToExport = '*'

# Cmdlets to export from this module
CmdletsToExport = '*'
}

 

And how do you generate a Guid ? simple … use .Net methods to quickly do that :

[guid]::NewGuid().Guid

 

Summary:

Well thats it for today 🙂 We have narrowed our resources and evaluated their types. We discussed how to create resource property and what parameters we can use fot that instance . And lastly we initially created our module and modified its manifest. So I think we are on really good track to start write of our resource methods in next post in this series.

 

Stay tuned for more! Catch up with all changes/Comment / Pull ->  on GitHub (https://github.com/RafPe/cWebAdmin) and till then !

 

 

 

 

2

PowerShell – Creating DSC module – Part 1

logo-powershell-520x245

Hey ,

As you probably know in world of DevOps a neat feature as DSC is must have and must do considering what it is capable of.  Since recently I have been working a lot with webservers I decided it took to long to get appropiate configuration in place. Considering event though we had some legacy scripts doing work , sometimes we had discripiencis which were really hard to solve (as finding root cause happening randomly on servers was fun )

So with this post I will be introducing you to creation of new DSC module with best practices and experience of myself and people from all over world (thanks GitHub). In many cases I will be referring you to external sources of information but the reason to that is simple – I dont want to duplicate information contained there.

Repo used for this excersise is available under https://github.com/RafPe/cWebAdmin so feel free to comment/contribute as it might be that you will find a better approach.

To be clear from beggining I will be using PSv5 as it offers me the most up to date access to cmdlets

PS C:\Program Files\WindowsPowerShell\Modules> $PSVersionTable

Name                           Value                                                       
----                           -----                                                       
PSVersion                      5.0.10105.0                                                 
WSManStackVersion              3.0                                                         
SerializationVersion           1.1.0.1                                                     
CLRVersion                     4.0.30319.42000                                             
BuildVersion                   10.0.10105.0                                                
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                                     
PSRemotingProtocolVersion      2.3                                                         

 

For creation of resource we will be using DSC module called xDscResourceDesigner. If you will check that module you will see the latest updates and description of cmdlets

If you download the tool make sure its available under $env:ProgramFiles\WindowsPowerShell\Modules

Once confirmed you can just import the module by typing :

Import-Module xDSCResourceDesigner

Plan your resource:

Before we go any further it is important to plan your DSC resource accordingly. Think here of “LEGO” 🙂 Ahhhh yes – the good days when you used your imagination to build skyscrapers and pirate ships. In both cases they are much a like 😀 a lot of reusable pieces that interconnects and creates amazing things.

Firstly we will prepare our folder structure. As you can see in example below (taken from Microsoft GitHub) we have :

xNetworking
   xNetworking.psd1
   DSCResources
       MSFT\_xDNSServerAddress
           MSFT\_xDNSServerAddress.psm1
           MSFT\_xDNSServerAddress.schema.mof
       MSFT\_xIPAddress
           MSFT\_xIPAddress.psm1
           MSFT\_xIPAddress.schema.mof
       MSFT\_xIPAddress
           MSFT\_xIPAddress.psm1
           MSFT\_xIPAddress.schema.mof
  • root folder with important module manifest.
  • Then folder containing our resources called DSCResources.
  • Every resource has its own folder and the folder name is the full name of resource (in most of cases this is longer than friendly name).
  • Within each of the folders you have script module (.psm1) and a schema (.schema.mof) file

The decision “To bundle or not to bundle” belongs to you. Since I want to control resources from single module I go for bundle.

 

 

Its all about your resources:

So in order to get going with DSC we will need our resources. Using aforementioned xDscResourceDesigner we will be able to properly create them. In the next post I will go into details of creating resources – their parameters and how to update them if necessary.

 

Whats in DSC :

If we open DSC module  we will find 3 primary DSC TargetResource functions (every DSC resource will have them ):

  • Get – this will get whatever we need to validate
  • Set – this will set whatever we need to set
  • Test – this will validate whatever it is we need to validate and will return a true or false state

The diagram below shows more in detail the flow :

DSC flow

Test-TargetResource is essential as this function is responsible for checking if your target resource exists or not. If it exists, this function must return True otherwise False . Proper writing this function will allow for DSC to deliver desired results.

Set-TargetResource function makes required changes on target resource. It gets called only if  target resource is not in desired state .

The Get-TargetResource function, is used to retrieve the current state of the resource instance.

 

 

Links :

There are several links worth of looking at (that I can recommend you to ) :

There are probably more (and newer ones ) so drop comment and I will update the list so ppl would be able to find them.

 

Summary for part 1:

So this is it for today 🙂 In the next post we will dive in details into :

  • Creating DSC resources and parameters for New-xDscResourceProperty
  • Creating module manifest
  • Talk about reusable scripting and what to avoid when writing scripts
  • …. and much more 🙂

 

Thanks!

RafPe

 

 

 

1

Road to challenges in IT

Hey ,

It has been long and quiet in last 2 years I think but this times comes to an end. A lot have been happening in regards to learning curve of SCCM/SCOM/ PowerShell  (especially DSc part) and REST Apis.

Nowadays we cannot forget about importance of cloud and hybrid environments and Docker technology!

With all of that I can assure you that from now I will be on regular basis sharing as much as possible from challenges I have came across and from the news I got from the engineering world!

As usual the primary forcus of my experience is providing advanced automation solutions with maintaining security and availability of your services (nop – not forgot -> scalability as well 😀 )

So stay tuned / fork GitHub and enjoy the automation!