Failed when running powershell code in azure automation - azure

Question

I set an azure policy adding two tags, which are CreatedTime and Type.
The value of CreatedTime is utcNow(), which default format is 'yyyy-MM-ddTHH:mm:ss.fffffffZ'.
My goal is to delete all resources whose Type is private and created time is longer than 2 days by running powershell code in azure automation.
I have done it in power shell locally, but when I run the code in automation, it failed. I will post the code and the error page below.
Anybody can tell me what's wrong with my code? Or I miss something?
This is my code in Azure Automation:
$connectionName = "AzureRunAsConnection"
try
{
# Get the connection "AzureRunAsConnection "
$servicePrincipalConnection=Get-AutomationConnection -Name $connectionName
"Logging in to Azure..."
Add-AzureRmAccount `
-ServicePrincipal `
-TenantId $servicePrincipalConnection.TenantId `
-ApplicationId $servicePrincipalConnection.ApplicationId `
-CertificateThumbprint
$servicePrincipalConnection.CertificateThumbprint
}
catch {
if (!$servicePrincipalConnection)
{
$ErrorMessage = "Connection $connectionName not found."
throw $ErrorMessage
} else{
Write-Error -Message $_.Exception
throw $_.Exception
}
}
$AllRes = (get-AzureRMResource).ResourceId
$TimeOutDays=2
foreach ($Res in $AllRes){
$Resource = Get-AzureRMResource -ResourceId $Res
$Tags=$Resource.Tags
$TypeInTags=$Tags['Type']
$CreatedTimeInTags=$Tags['CreatedTime']
try{
$CreatedTime=[Datetime]::ParseExact($CreatedTimeInTags, 'MM/dd/yyyy HH:mm:ss', $null)
}
catch{
$CreatedTime=[Datetime]::ParseExact($CreatedTimeInTags, 'yyyy-MM-ddTHH:mm:ss.fffffffZ', $null)
}
finally
{
$CreatedTime
}
$daypan=((get-date)-$CreatedTime).Days
if($TypeInTags -eq 'private')
{
if($daypan -gt $TimeOutDays)
{
$daypan
Remove-AzureRMResource -ResourceId $Res -Force
}
}
}
This is the error page:
Suspended
The runbook job was attempted 3 times, but it failed each time. Common reasons that runbook jobs fail can be found here: https://learn.microsoft.com/en-us/azure/automation/automation-troubleshooting-automation-errors
A piece of error message:
Get-AzureRMResource : ResourceNotFound : The Resource
'microsoft.alertsmanagement/smartDetectorAlertRules/Failure+Anomalies+-+arrowbottest2-config' under resource group
'arrowbot2' was not found. For more details please go to https://aka.ms/ARMResourceNotFoundFix
At line:28 char:17
+ $Resource = Get-AzureRMResource -ResourceId $Res
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : CloseError: (:) [Get-AzureRmResource], ErrorResponseMessageException
+ FullyQualifiedErrorId :
ResourceNotFound,Microsoft.Azure.Commands.ResourceManager.Cmdlets.Implementation.GetAzureResourceCmdlet
Exception calling "ParseExact" with "3" argument(s): "String was not recognized as a valid DateTime."
At line:34 char:5
+ $CreatedTime=[Datetime]::ParseExact($Tags['CreatedTime'], 'yyyy-M ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : FormatException
Cannot find an overload for "op_Subtraction" and the argument count: "2".
At line:35 char:5
+ $daypan=((get-date)-$CreatedTime).Days
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodCountCouldNotFindBest
Cannot find an overload for "op_Subtraction" and the argument count: "2".
At line:35 char:5
+ $daypan=((get-date)-$CreatedTime).Days
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodCountCouldNotFindBest
Exception calling "ParseExact" with "3" argument(s): "String was not recognized as a valid DateTime."
At line:34 char:5
+ $CreatedTime=[Datetime]::ParseExact($Tags['CreatedTime'], 'yyyy-M ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : FormatException
For the type of $Tags['CreatedTime'], I did this for a test: $Tags['CreatedTime'].GetType().FullName.

Answer 1

Since you say The value of CreatedTime is utcNow(), then that value is already a DateTime object and you should not treat it as string. (you think it is a string, because when you write it out to console, it will show its ToString() representation)
Simply do
$CreatedTime=$Tags['CreatedTime']
You can test this with a write-host $Tags['CreatedTime'].GetType().FullName

Answer 2

There are two things wrong.
1.Didn't specify the resource I need.
Detailes:
That's the reason for the error message: Can not index to a null array. I traverse the entire resource in my subscription, but the
resources created before I set the policy do not have a Tag named
"CreatedTime" or "Type", so when I run $Tags=$Resource.Tags, it
said Can not index to a null array.
My solution:
Do $AllRes = (get-AzResource -TagName "CreatedTime").ResourceId other than $AllRes = (get-AzureRMResource).ResourceId.
I found that AzureRM module don't
recognize -TagName as a variable, so I import the Az module and
change every AzureRM module to Az module.
2.Confused with utcNow().
Details:
As I said, with utcNow() function I get a DateTime object with default
format 'yyyy-MM-ddTHH:mm:ss.fffffffZ', after testing a lot,
I found some special resources like application insight' tag value is
not formated with 'yyyy-MM-ddTHH:mm:ss.fffffffZ', and when I call
it, it comes to a string.
My solution:
So when I use it comparing to get-date, I
need to do two things:
(1)Change the string to DateTime object;
(2)Use try-catch to meet two kinds of formats.