Azure Virtual Machine Agent Overview - Azure Virtual Machines (2024)

Article
08/02/2022
5 minutes to read

The Microsoft Azure Virtual Machine Agent (VM Agent) is a secure, lightweight process that manages virtual machine (VM) interaction with the Azure Fabric Controller. The VM Agent has a primary role in enabling and executing Azure virtual machine extensions. VM Extensions enable post-deployment configuration of VM, such as installing and configuring software. VM extensions also enable recovery features such as resetting the administrative password of a VM. Without the Azure VM Agent, VM extensions cannot be run.

This article details installation and detection of the Azure Virtual Machine Agent.

Install the VM Agent

Azure Marketplace image

The Azure VM Agent is installed by default on any Windows VM deployed from an Azure Marketplace image. When you deploy an Azure Marketplace image from the portal, PowerShell, Command Line Interface, or an Azure Resource Manager template, the Azure VM Agent is also installed.

The Windows Guest Agent Package is broken into two parts:

Provisioning Agent (PA)
Windows Guest Agent (WinGA)

To boot a VM you must have the PA installed on the VM, however the WinGA does not need to be installed. At VM deploy time, you can select not to install the WinGA. The following example shows how to select the provisionVmAgent option with an Azure Resource Manager template:

Manual installation

The Windows VM agent can be manually installed with a Windows installer package. Manual installation may be necessary when you create a custom VM image that is deployed to Azure. To manually install the Windows VM Agent, download the VM Agent installer and select the latest release. You can also search a specific version in the GitHub Windows IaaS VM Agent releases. The VM Agent is supported on Windows Server 2008 (64 bit) and later.

Note

It is important to update the AllowExtensionOperations option after manually installing the VMAgent on a VM that was deployed from image without ProvisionVMAgent enable.

$vm.OSProfile.AllowExtensionOperations = $true$vm | Update-AzVM

Prerequisites

The Windows VM Agent needs at least Windows Server 2008 SP2 (64-bit) to run, with the .NET Framework 4.0. See Minimum version support for virtual machine agents in Azure.
Ensure your VM has access to IP address 168.63.129.16. For more information, see What is IP address 168.63.129.16.
Ensure that DHCP is enabled inside the guest VM. This is required to get the host or fabric address from DHCP for the IaaS VM Agent and extensions to work. If you need a static private IP, you should configure it through the Azure portal or PowerShell, and make sure the DHCP option inside the VM is enabled. Learn more about setting up a static IP address with PowerShell.
Running the VM Agent in a "Nested Virtualization" VM might lead to unpredictable behavior, hence it's not supported in that Dev/Test scenario.

Detect the VM Agent

PowerShell

The Azure Resource Manager PowerShell module can be used to retrieve information about Azure VMs. To see information about a VM, such as the provisioning state for the Azure VM Agent, use Get-AzVM:

Get-AzVM

The following condensed example output shows the ProvisionVMAgent property nested inside OSProfile. This property can be used to determine if the VM agent has been deployed to the VM:

OSProfile : ComputerName : myVM AdminUsername : myUserName WindowsConfiguration : ProvisionVMAgent : True EnableAutomaticUpdates : True

The following script can be used to return a concise list of VM names (running Windows OS) and the state of the VM Agent:

$vms = Get-AzVMforeach ($vm in $vms) { $agent = $vm | Select -ExpandProperty OSProfile | Select -ExpandProperty Windowsconfiguration | Select ProvisionVMAgent Write-Host $vm.Name $agent.ProvisionVMAgent}

The following script can be used to return a concise list of VM names (running Linux OS) and the state of the VM Agent:

$vms = Get-AzVMforeach ($vm in $vms) { $agent = $vm | Select -ExpandProperty OSProfile | Select -ExpandProperty Linuxconfiguration | Select ProvisionVMAgent Write-Host $vm.Name $agent.ProvisionVMAgent}

Manual Detection

When logged in to a Windows VM, Task Manager can be used to examine running processes. To check for the Azure VM Agent, open Task Manager, click the Details tab, and look for a process name WindowsAzureGuestAgent.exe. The presence of this process indicates that the VM agent is installed.

Upgrade the VM Agent

The Azure VM Agent for Windows is automatically upgraded on images deployed from the Azure Marketplace. The new versions are stored in Azure Storage, so please ensure you don't have firewalls blocking access. As new VMs are deployed to Azure, they receive the latest VM agent at VM provision time. If you have installed the agent manually or are deploying custom VM images you will need to manually update to include the new VM agent at image creation time.

Windows Guest Agent Automatic Logs Collection

Windows Guest Agent has a feature to automatically collect some logs. This feature is controlled by the CollectGuestLogs.exe process.It exists for both PaaS Cloud Services and IaaS Virtual Machines and its goal is to quickly & automatically collect some diagnostics logs from a VM - so they can be used for offline analysis.The collected logs are Event Logs, OS Logs, Azure Logs and some registry keys. It produces a ZIP file that is transferred to the VM’s Host. This ZIP file can then be looked at by Engineering Teams and Support professionals to investigate issues on request of the customer owning the VM.

Guest Agent and OSProfile certificates

The Azure VM Agent is responsible for installing the certificates referenced in the OSProfile of a VM or Virtual Machine Scale Set.If you manually remove these certificates from the certificates MMC console inside the guest VM, it is expected that the guest agent will add them back.To permanently remove a certificate, you will have to remove it from the OSProfile, and then remove it from within the guest operating system.

For a Virtual Machine, use the Remove-AzVMSecret to remove certificates from the OSProfile.

For more information on Virtual Machine Scale Set certificates, see Virtual Machine Scale Sets - How do I remove deprecated certificates?

Next steps

For more information about VM extensions, see Azure virtual machine extensions and features overview.