Automate VMware CPU & Memory Resize
with Jenkins Parameterised Build

📋 Overview

Manually resizing VMs in VMware vSphere is a common but time-consuming operational task — especially when it involves coordinating across multiple datacentres, shutting down VMs safely, verifying changes, and notifying teams. One mistake can mean downtime or an incorrectly sized machine nobody notices for weeks.

This guide walks through a production-ready PowerShell + PowerCLI solution integrated with Jenkins Parameterised Build, giving your infrastructure team a simple, auditable, self-service interface to resize VMs in both the PROD and DR vCenter environments — with zero need to touch a script or a vCenter console directly.

🚀 Why Jenkins Parameterised Build?

Jenkins Parameterised Builds turn any script into a governed, self-service interface. Engineers fill in a simple form and Jenkins handles the rest — no SSH sessions, no shared credentials in chat, no ad-hoc PowerShell runs.

✅ Prerequisites

• Jenkins Server (LTS recommended)

  Windows-based Jenkins agent recommended so PowerShell runs natively. Jenkins 2.346+ supports modern pipeline syntax.

• VMware PowerCLI installed on Jenkins Agent

  Run: Install-Module VMware.PowerCLI -Scope AllUsers -Force on the agent node. Disable CEIP: Set-PowerCLIConfiguration -Scope AllUsers -ParticipateInCEIP $false -Confirm:$false

• Jenkins Plugins Required

  Install: PowerShell Plugin, Credentials Binding Plugin, Email Extension Plugin. Go to Manage Jenkins → Plugin Manager to install.

• vCenter Service Account

  Create a dedicated read/write service account in vCenter with VM modify permissions. Store credentials in Jenkins → Credentials → Global Credentials.

• SMTP Relay Configured

  Ensure the Jenkins agent can reach the SMTP relay (172.0.2.35 in this setup) for email alerting.

• Log Directory Created on Agent

  Create the path C:\_vSphere_Patching\CPU_Memory_PS_Logs\ on the agent before first run. The script auto-creates log files on each execution.

⚙️ Jenkins Job Setup — Step by Step

1. Create a New Freestyle Job

Go to Jenkins Dashboard → New Item. Name it VMware-CPU-Memory-Resize, select Freestyle Project, then click OK.

2. Enable "This project is parameterised"

Tick This project is parameterised under the General section. Add the following parameters:

3. Bind Credentials as Environment Variables

Under Build Environment, tick Use secret text(s) or file(s). Add bindings for your vCenter credentials stored in Jenkins Credentials store. Map them to environment variables Username and Password so the script picks them up via $Env:Username and $Env:Password.

4. Add Build Step — Execute PowerShell

Add a Build Step → Execute Windows PowerShell step. In the script field enter:

& "C:\Scripts\VMware-CPU-Memory-Resize.ps1"

The script file should be placed on the Jenkins agent at the above path, or pulled from Git SCM (see optional step below).

5. (Optional) Source from Git Repository

Under Source Code Management, select Git and point to:

https://github.com/automatewithravi/VMware.git

Set the script path to the file in the repo. This ensures every build pulls the latest approved version of the script.

6. Configure Post-Build Email Notifications

Under Post-build Actions → Editable Email Notification, configure recipients and triggers. The script already handles failure emails inline, but Jenkins-level notifications provide an additional safety net for pipeline failures.

7. Save and Test

Click Save. Then click Build with Parameters and test with a non-critical VM first. Review the Console Output in Jenkins and the transcript log file generated on the agent.

🔀 Script Logic Flow

The script follows a deterministic flow on every run — connect, validate, shutdown, modify, verify, start, alert.

📄 The PowerShell Script

The script is structured into clean reusable functions — Connect-VCenter, Stop-VMSafely, Set-VMCPU, Set-VMMemory, Confirm-CPUChange, and Send-AlertEmail — while preserving the original logic exactly. No logic modification has been made.

# ── HELPER FUNCTIONS ───────────────────────────────────────────

function Send-AlertEmail {
    param ([string]$Subject, [string]$Body)
    Send-MailMessage -SmtpServer $SMTP_Server `
        -From $Mail_From -To $Mail_To `
        -Subject ($Subject + " - " + (Get-Date -Format "dd-MM-yyyy")) `
        -Body $Body
}

function Connect-VCenter {
    param ([string]$VCenterName, [string]$Label)
    $Connection = Connect-VIServer -Server $VCenterName -User $Username -Password $Password
    if ($Connection.IsConnected -ne $true) { Write-Host " Unable to connect to $Label"; Exit 1 }
    Write-Host " $Label vCenter connected." -ForegroundColor Green
}

function Stop-VMSafely {
    param ([string]$VMName, [int]$GraceSeconds = 180)
    Get-VM | Where-Object { $_.Name -like $VMName } | Stop-VMGuest -Confirm:$false
    Start-Sleep -Seconds $GraceSeconds
    Get-VM | Where-Object { $_.Name -like $VMName -and $_.PowerState -like "*On" } | Stop-VM -Confirm:$false
}

function Set-VMCPU {
    param ([string]$VMName, [int]$NumCPU)
    Get-VM -Name $VMName | Set-VM -NumCpu $NumCPU -Confirm:$false
}

function Set-VMMemory {
    param ([string]$VMName, [int]$MemoryGB)
    Get-VM -Name $VMName | Set-VM -MemoryGB $MemoryGB -Confirm:$false
}

function Confirm-CPUChange {
    param ([string]$VMName, [int]$Expected)
    $Actual = (Get-VM -Name $VMName).NumCpu
    return $Actual -eq $Expected
}

function Confirm-MemoryChange {
    param ([string]$VMName, [int]$Expected)
    $Actual = (Get-VM -Name $VMName).MemoryGB
    return $Actual -eq $Expected
}

# ── EXECUTION FLOW ─────────────────────────────────────────────

$VM_PowerStatus = (Get-VM -Name $VMName).PowerState

if ($CPU -eq "yes" -and $Memory -ne "yes") {
    if ($VM_PowerStatus -eq "PoweredOn") { Stop-VMSafely -VMName $VMName }
    Set-VMCPU -VMName $VMName -NumCPU $NumberofCPU_required
    if (Confirm-CPUChange -VMName $VMName -Expected $NumberofCPU_required) { Start-VMAndVerify -VMName $VMName }
}
elseif ($Memory -eq "yes" -and $CPU -ne "yes") {
    if ($VM_PowerStatus -eq "PoweredOn") { Stop-VMSafely -VMName $VMName }
    Set-VMMemory -VMName $VMName -MemoryGB $Memory_Size_required
    if (Confirm-MemoryChange -VMName $VMName -Expected $Memory_Size_required) { Start-VMAndVerify -VMName $VMName }
}
elseif ($CPU -eq "yes" -and $Memory -eq "yes") {
    if ($VM_PowerStatus -eq "PoweredOn") { Stop-VMSafely -VMName $VMName }
    Set-VMMemory -VMName $VMName -MemoryGB $Memory_Size_required
    Set-VMCPU    -VMName $VMName -NumCPU    $NumberofCPU_required
    $MemOK = Confirm-MemoryChange -VMName $VMName -Expected $Memory_Size_required
    $CPUOK = Confirm-CPUChange    -VMName $VMName -Expected $NumberofCPU_required
    if ($MemOK -and $CPUOK) { Start-VMAndVerify -VMName $VMName }
}

🛠️ Common Issues & Troubleshooting

🏷️ Tags