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VMNetworkAdapter: throws `You cannot call a method on a null-valued expression` - introduced in version 3.17
Details of the scenario you tried and the problem that is occurring
I'm using puppet's dsc xhyper_v module (a copy of this one) to manage xvmnetworkadapter. On version 3.16.0-0-3, the following code works. On version 3.17.0-0-0, it breaks.
#Puppet code
dsc_xvmnetworkadapter{'VMNetAdapter_V_Management':
dsc_ensure => 'Present',
dsc_name => 'V-Management',
dsc_switchname => 'guest_switch',
dsc_vmname => 'ManagementOS',
dsc_id => fqdn_uuid("v.management.${$facts['fqdn']}"),
}
In version 3.16.0-0-3, the output is:
[0;36mDebug: dsc_xvmnetworkadapter: invocable_resource: {:parameters=>{:dsc_name=>{:value=>"V-Management", :mof_type=>"String", :mof_is_embedded=>false}, :dsc_switchname=>{:value=>"guest_switch", :mof_type=>"String", :mof_is_embedded=>false}, :dsc_vmname=>{:value=>"ManagementOS", :mof_type=>"String", :mof_is_embedded=>false}, :dsc_id=>{:value=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", :mof_type=>"String", :mof_is_embedded=>false}}, :name=>"dsc_xvmnetworkadapter", :dscmeta_resource_friendly_name=>"xVMNetworkAdapter", :dscmeta_resource_name=>"MSFT_xVMNetworkAdapter", :dscmeta_resource_implementation=>nil, :dscmeta_module_name=>"xHyper-V", :dscmeta_module_version=>"3.16.0.0", :dsc_invoke_method=>"get", :vendored_modules_path=>"C:/ProgramData/PuppetLabs/puppet/cache/lib/puppet_x/dsc_resources", :attributes=>nil}[0m
[0;36mDebug: dsc_xvmnetworkadapter: Script:
function new-pscredential {
[CmdletBinding()]
param (
[parameter(Mandatory = $true,
ValueFromPipelineByPropertyName = $true)]
[string]
$user,
[parameter(Mandatory = $true,
ValueFromPipelineByPropertyName = $true)]
[string]
$password
)
$secpasswd = ConvertTo-SecureString $password -AsPlainText -Force
$credentials = New-Object System.Management.Automation.PSCredential ($user, $secpasswd)
return $credentials
}
Function ConvertTo-CanonicalResult {
[CmdletBinding()]
param(
[Parameter(Mandatory, Position = 1)]
[psobject]
$Result,
[Parameter(DontShow)]
[string]
$PropertyPath,
[Parameter(DontShow)]
[int]
$RecursionLevel = 0
)
$MaxDepth = 5
$CimInstancePropertyFilter = { $_.Definition -match 'CimInstance' -and $_.Name -ne 'PSDscRunAsCredential' }
# Get the properties which are/aren't Cim instances
$ResultObject = @{ }
$ResultPropertyList = $Result | Get-Member -MemberType Property | Where-Object { $_.Name -ne 'PSComputerName' }
$CimInstanceProperties = $ResultPropertyList | Where-Object -FilterScript $CimInstancePropertyFilter
foreach ($Property in $ResultPropertyList) {
$PropertyName = $Property.Name
if ($Property -notin $CimInstanceProperties) {
$Value = $Result.$PropertyName
if ($PropertyName -eq 'Ensure' -and [string]::IsNullOrEmpty($Result.$PropertyName)) {
# Just set 'Present' since it was found /shrug
# If the value IS listed as absent, don't update it unless you want flapping
$Value = 'Present'
}
else {
if ([string]::IsNullOrEmpty($value)) {
# While PowerShell can happily treat empty strings as valid for returning
# an undefined enum, Puppet expects undefined values to be nil.
$Value = $null
}
if ($Value.Count -eq 1 -and $Property.Definition -match '\\[\\]') {
$Value = @($Value)
}
}
}
elseif ($null -eq $Result.$PropertyName) {
if ($Property -match 'InstanceArray') {
$Value = @()
}
else {
$Value = $null
}
}
elseif ($Result.$PropertyName.GetType().Name -match 'DateTime') {
# Handle DateTimes especially since they're an edge case
$Value = Get-Date $Result.$PropertyName -UFormat "%Y-%m-%dT%H:%M:%S%Z"
}
else {
# Looks like a nested CIM instance, recurse if we're not too deep in already.
$RecursionLevel++
if ($PropertyPath -eq [string]::Empty) {
$PropertyPath = $PropertyName
}
else {
$PropertyPath = "$PropertyPath.$PropertyName"
}
if ($RecursionLevel -gt $MaxDepth) {
# Give up recursing more than this
return $Result.ToString()
}
$Value = foreach ($item in $Result.$PropertyName) {
ConvertTo-CanonicalResult -Result $item -PropertyPath $PropertyPath -RecursionLevel ($RecursionLevel + 1) -WarningAction Continue
}
# The cim instance type is the last component of the type Name
# We need to return this for ruby to compare the result hashes
# We do NOT need it for the top-level properties as those are defined in the type
If ($RecursionLevel -gt 1 -and ![string]::IsNullOrEmpty($Value) ) {
# If there's multiple instances, you need to add the type to each one, but you
# need to specify only *one* name, otherwise things end up *very* broken.
if ($Value.GetType().Name -match '\[\]') {
$Value | ForEach-Object -Process {
$_.cim_instance_type = $Result.$PropertyName.CimClass.CimClassName[0]
}
} else {
$Value.cim_instance_type = $Result.$PropertyName.CimClass.CimClassName
# Ensure that, if it should be an array, it is
if ($Result.$PropertyName.GetType().Name -match '\[\]') {
$Value = @($Value)
}
}
}
}
if ($Property.Definition -match 'InstanceArray') {
If ($null -eq $Value -or $Value.GetType().Name -notmatch '\[\]') { $Value = @($Value) }
}
$ResultObject.$PropertyName = $Value
}
# Output the final result
$ResultObject
}
$script:ErrorActionPreference = 'Stop'
$script:WarningPreference = 'SilentlyContinue'
$response = @{
indesiredstate = $false
rebootrequired = $false
errormessage = ''
}
$InvokeParams = @{Name = 'xVMNetworkAdapter'; Method = 'get'; Property = @{name = 'V-Management'; switchname = 'guest_switch'; vmname = 'ManagementOS'; id = 'e49f84e4-a553-595d-9096-ada90a8ec9e7'}; ModuleName = @{ModuleName = 'C:/ProgramData/PuppetLabs/puppet/cache/lib/puppet_x/dsc_resources/xHyper-V/xHyper-V.psd1'; RequiredVersion = '3.16.0.0'}}
Try {
$Result = Invoke-DscResource @InvokeParams
} catch {
$Response.errormessage = $_.Exception.Message
return ($Response | ConvertTo-Json -Compress)
} Finally {
If (![string]::IsNullOrEmpty($UnmungedPSModulePath)) {
# Reset the PSModulePath
[System.Environment]::SetEnvironmentVariable('PSModulePath', $UnmungedPSModulePath, [System.EnvironmentVariableTarget]::Machine)
$env:PSModulePath = [System.Environment]::GetEnvironmentVariable('PSModulePath', 'machine')
}
}
# keep the switch for when Test passes back changed properties
Switch ($invokeParams.Method) {
'Test' {
$Response.indesiredstate = $Result.InDesiredState
return ($Response | ConvertTo-Json -Compress)
}
'Set' {
$Response.indesiredstate = $true
$Response.rebootrequired = $Result.RebootRequired
return ($Response | ConvertTo-Json -Compress)
}
'Get' {
$CanonicalizedResult = ConvertTo-CanonicalResult -Result $Result
return ($CanonicalizedResult | ConvertTo-Json -Compress -Depth 10)
}
}
[0m
[0;36mDebug: dsc_xvmnetworkadapter: raw data received: {"Id"=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", "Name"=>"V-Management", "ResourceId"=>nil, "MacAddress"=>"00155DD15209", "DynamicMacAddress"=>false, "PsDscRunAsCredential"=>nil, "ConfigurationName"=>nil, "Ensure"=>"Present", "DependsOn"=>nil, "SourceInfo"=>nil, "SwitchName"=>"guest_switch", "ModuleVersion"=>"3.16.0.0", "ModuleName"=>"C:/ProgramData/PuppetLabs/puppet/cache/lib/puppet_x/dsc_resources/xHyper-V/xHyper-V.psd1", "VMName"=>"ManagementOS"}[0m
[0;36mDebug: dsc_xvmnetworkadapter: Returned to Puppet as {:dsc_dynamicmacaddress=>false, :dsc_ensure=>"Present", :dsc_id=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", :dsc_macaddress=>"00155DD15209", :dsc_name=>"V-Management", :dsc_switchname=>"guest_switch", :dsc_vmname=>"ManagementOS", :name=>"VMNetAdapter_V_Management"}[0m
[0;36mDebug: dsc_xvmnetworkadapter: Canonicalized Resources: [{:dsc_ensure=>"Present", :dsc_id=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", :dsc_name=>"V-Management", :dsc_switchname=>"guest_switch", :dsc_vmname=>"ManagementOS", :name=>"VMNetAdapter_V_Management"}][0m
In version 3.17.0-0-0, the I get the message You cannot call a method on a null-valued expression, as seen in this output: The same is true for version 3.17.0-0-3.
[0;36mDebug: dsc_xvmnetworkadapter: retrieving {:name=>"VMNetAdapter_V_Management", :dsc_ensure=>"Present", :dsc_name=>"V-Management", :dsc_switchname=>"guest_switch", :dsc_vmname=>"ManagementOS", :dsc_id=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", :require=>["Dsc_xvmswitch[VMSwitch_guest_switch]"]}
[0;36mDebug: dsc_xvmnetworkadapter: invocable_resource: {:parameters=>{:dsc_name=>{:value=>"V-Management", :mof_type=>"String", :mof_is_embedded=>false}, :dsc_switchname=>{:value=>"guest_switch", :mof_type=>"String", :mof_is_embedded=>false}, :dsc_vmname=>{:value=>"ManagementOS", :mof_type=>"String", :mof_is_embedded=>false}, :dsc_id=>{:value=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", :mof_type=>"String", :mof_is_embedded=>false}}, :name=>"dsc_xvmnetworkadapter", :dscmeta_resource_friendly_name=>"xVMNetworkAdapter", :dscmeta_resource_name=>"MSFT_xVMNetworkAdapter", :dscmeta_resource_implementation=>"MOF", :dscmeta_module_name=>"xHyper-V", :dscmeta_module_version=>"3.17.0.0", :dsc_invoke_method=>"get", :vendored_modules_path=>"C:/ProgramData/PuppetLabs/puppet/cache/lib/puppet_x/xhyper_v/dsc_resources", :attributes=>nil}[0m
[0;36mDebug: dsc_xvmnetworkadapter: Script:
function new-pscredential {
[CmdletBinding()]
param (
[parameter(Mandatory = $true,
ValueFromPipelineByPropertyName = $true)]
[string]
$user,
[parameter(Mandatory = $true,
ValueFromPipelineByPropertyName = $true)]
[string]
$password
)
$secpasswd = ConvertTo-SecureString $password -AsPlainText -Force
$credentials = New-Object System.Management.Automation.PSCredential ($user, $secpasswd)
return $credentials
}
Function ConvertTo-CanonicalResult {
[CmdletBinding()]
param(
[Parameter(Mandatory, Position = 1)]
[psobject]
$Result,
[Parameter(DontShow)]
[string]
$PropertyPath,
[Parameter(DontShow)]
[int]
$RecursionLevel = 0
)
$MaxDepth = 5
$CimInstancePropertyFilter = { $_.Definition -match 'CimInstance' -and $_.Name -ne 'PSDscRunAsCredential' }
# Get the properties which are/aren't Cim instances
$ResultObject = @{ }
$ResultPropertyList = $Result | Get-Member -MemberType Property | Where-Object { $_.Name -ne 'PSComputerName' }
$CimInstanceProperties = $ResultPropertyList | Where-Object -FilterScript $CimInstancePropertyFilter
foreach ($Property in $ResultPropertyList) {
$PropertyName = $Property.Name
if ($Property -notin $CimInstanceProperties) {
$Value = $Result.$PropertyName
if ($PropertyName -eq 'Ensure' -and [string]::IsNullOrEmpty($Result.$PropertyName)) {
# Just set 'Present' since it was found /shrug
# If the value IS listed as absent, don't update it unless you want flapping
$Value = 'Present'
}
else {
if ([string]::IsNullOrEmpty($value)) {
# While PowerShell can happily treat empty strings as valid for returning
# an undefined enum, Puppet expects undefined values to be nil.
$Value = $null
}
if ($Value.Count -eq 1 -and $Property.Definition -match '\\[\\]') {
$Value = @($Value)
}
}
}
elseif ($null -eq $Result.$PropertyName) {
if ($Property -match 'InstanceArray') {
$Value = @()
}
else {
$Value = $null
}
}
elseif ($Result.$PropertyName.GetType().Name -match 'DateTime') {
# Handle DateTimes especially since they're an edge case
$Value = Get-Date $Result.$PropertyName -UFormat "%Y-%m-%dT%H:%M:%S%Z"
}
else {
# Looks like a nested CIM instance, recurse if we're not too deep in already.
$RecursionLevel++
if ($PropertyPath -eq [string]::Empty) {
$PropertyPath = $PropertyName
}
else {
$PropertyPath = "$PropertyPath.$PropertyName"
}
if ($RecursionLevel -gt $MaxDepth) {
# Give up recursing more than this
return $Result.ToString()
}
$Value = foreach ($item in $Result.$PropertyName) {
ConvertTo-CanonicalResult -Result $item -PropertyPath $PropertyPath -RecursionLevel ($RecursionLevel + 1) -WarningAction Continue
}
# The cim instance type is the last component of the type Name
# We need to return this for ruby to compare the result hashes
# We do NOT need it for the top-level properties as those are defined in the type
If ($RecursionLevel -gt 1 -and ![string]::IsNullOrEmpty($Value) ) {
# If there's multiple instances, you need to add the type to each one, but you
# need to specify only *one* name, otherwise things end up *very* broken.
if ($Value.GetType().Name -match '\[\]') {
$Value | ForEach-Object -Process {
$_.cim_instance_type = $Result.$PropertyName.CimClass.CimClassName[0]
}
} else {
$Value.cim_instance_type = $Result.$PropertyName.CimClass.CimClassName
# Ensure that, if it should be an array, it is
if ($Result.$PropertyName.GetType().Name -match '\[\]') {
$Value = @($Value)
}
}
}
}
if ($Property.Definition -match 'InstanceArray') {
If ($null -eq $Value -or $Value.GetType().Name -notmatch '\[\]') { $Value = @($Value) }
}
$ResultObject.$PropertyName = $Value
}
# Output the final result
$ResultObject
}
$script:ErrorActionPreference = 'Stop'
$script:WarningPreference = 'SilentlyContinue'
$response = @{
indesiredstate = $false
rebootrequired = $false
errormessage = ''
}
$InvokeParams = @{Name = 'xVMNetworkAdapter'; Method = 'get'; Property = @{name = 'V-Management'; switchname = 'guest_switch'; vmname = 'ManagementOS'; id = 'e49f84e4-a553-595d-9096-ada90a8ec9e7'}; ModuleName = @{ModuleName = 'C:/ProgramData/PuppetLabs/puppet/cache/lib/puppet_x/xhyper_v/dsc_resources/xHyper-V/xHyper-V.psd1'; RequiredVersion = '3.17.0.0'}}
Try {
$Result = Invoke-DscResource @InvokeParams
} catch {
$Response.errormessage = $_.Exception.Message
return ($Response | ConvertTo-Json -Compress)
} Finally {
If (![string]::IsNullOrEmpty($UnmungedPSModulePath)) {
# Reset the PSModulePath
[System.Environment]::SetEnvironmentVariable('PSModulePath', $UnmungedPSModulePath, [System.EnvironmentVariableTarget]::Machine)
$env:PSModulePath = [System.Environment]::GetEnvironmentVariable('PSModulePath', 'machine')
}
}
# keep the switch for when Test passes back changed properties
Switch ($invokeParams.Method) {
'Test' {
$Response.indesiredstate = $Result.InDesiredState
return ($Response | ConvertTo-Json -Compress)
}
'Set' {
$Response.indesiredstate = $true
$Response.rebootrequired = $Result.RebootRequired
return ($Response | ConvertTo-Json -Compress)
}
'Get' {
$CanonicalizedResult = ConvertTo-CanonicalResult -Result $Result
return ($CanonicalizedResult | ConvertTo-Json -Compress -Depth 10)
}
}
[0m
[0;36mDebug: dsc_xvmnetworkadapter: raw data received: {"rebootrequired"=>false, "indesiredstate"=>false, "errormessage"=>"You cannot call a method on a null-valued expression."}[0m
[1;31mError: dsc_xvmnetworkadapter: You cannot call a method on a null-valued expression.[0m
[0;36mDebug: dsc_xvmnetworkadapter: Canonicalized Resources: [{:name=>"VMNetAdapter_V_Management", :dsc_ensure=>"Present", :dsc_name=>"V-Management", :dsc_switchname=>"guest_switch", :dsc_vmname=>"ManagementOS", :dsc_id=>"e49f84e4-a553-595d-9096-ada90a8ec9e7", :require=>["Dsc_xvmswitch[VMSwitch_guest_switch]", "Notify[foobar]"]}][0m
Suggested solution to the issue
Did some code in the version 3.17 pull request add a reference that is not properly checked if it exists? Is it perhaps the inclusion of vlanid or networksetting, that I do not include but seems to be new in that version of the code?
The DSC configuration that is used to reproduce the issue (as detailed as possible)
N/A
The operating system the target node is running
OsName : Microsoft Windows Server 2016 Datacenter
OsOperatingSystemSKU : DatacenterServerEdition
OsArchitecture : 64-bit
WindowsBuildLabEx : 14393.4583.amd64fre.rs1_release.210730-1850
OsLanguage : en-US
OsMuiLanguages : {en-US}
Version and build of PowerShell the target node is running
Name Value
---- -----
PSVersion 5.1.14393.4583
PSEdition Desktop
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.14393.4583
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
Version of the DSC module that was used
3.16.0-0-3 - Known good
3.17.0-0-0--3 - Known bad.
I think PR #189 will resolve this when it is refactored, but we should add a unit test to verify the parameters in this issue.
