Question 104330 in Azure Question posted in
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Pick the last sequence and deploy a new resource with next sequence azure powershell

I am trying to automate the azure resource deployment using powershell.

Requirments : In a particular resource group(RG), there are multiple VMs. the naming convention are like,

XXX-XX-X-XXXXXX-VM-01,

XXX-XX-X-XXXXXX-VM-02,

XXX-XX-X-XXXXXX-VM-03.

I am trying to create a script which will look for the last sequence(is this case 03) and deploy the next VM with next sequence(here it should be 04).

I have the script to deploy the VM using powershell. Need help to fix the sequence logic.

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2

Answers


  1. 0

    I have a similar requirement and have been working on down the following route. In my case the numeric value is on the third element of the name, but I put in your value in hope this works for you.

    # I created an Array to hold the values returned from splitting the Name string.
$CurrentVal = @()

# Used a ForEach loop to Get VM in required Resource Group 
ForEach ($vmName in (Get-AzVM -ResourceGroupName <resourcegroupName>).Name){
   # Convert to Decimal the Split String
   $vmNum = [Decimal]($vmName.split('-')[5])
   #Add to the Array
   $CurrentVal = $Currentval + $vmNum
 } 

#Then got the value.
$nextVal = ($Currentval | measure -maximum).Maximum + 1

    With the returned value, I can then ceate the next VM.

    Regards

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  2. 0

    As a general reusable solution:

    function Get-NextString {
    param ([Parameter(ValueFromPipeline = $true)][String]$InputObject)
    begin {
        $Last, $Name = $Null
    }
    process {
        $Name, $Sequence = $_ -Split '(?=d*$)', 2
        if ([int]$Sequence -gt $Last) { $Last = $Sequence }
    }
    end {
        $Name + (1 + $Last).ToString("D$($Last.Length)")
    }
}

    usage:

    $List =
'XXX-XX-X-XXXXXX-VM-01',
'XXX-XX-X-XXXXXX-VM-02',
'XXX-XX-X-XXXXXX-VM-03'

$List |Get-NextString
XXX-XX-X-XXXXXX-VM-04

    Explanations:

    • param ([Parameter(ValueFromPipeline = $true)][String]$InputObject) accepts (multiple) strings from the pipeline, each string is processed as $_, the current item
    • For the begin, process and end blocks, read about Functions Advanced Methods
    • $Name, $Sequence = $_ -Split '(?=d*$)', 2 splits the current sting in the prefix ($name) and the sequence number. See also: Regular Expression
    • if ([int]$Sequence -gt $Last) { $Last = $Sequence } catch the highest number
      • The [int] in front of the $Sequence will force an numeric comparison
    • $Name + (1 + $Last).ToString("D$($Last.Length)") outputs the new string.
      • (1 + $Last) increase the $Last number with 1. Note that the $Last string will be automatically cast to an integer as the operant at the left hand side of the operator is an integer (1).
      • ToString("D$($Last.Length)") will format the sequence to the same number of digits as contained by $Last, see also: Pad a Number with Leading Zeros
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