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Get started with the Azure Virtual Desktop Agent

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In the Azure Virtual Desktop Service framework, there are three main components: the Remote Desktop client, the service, and the virtual machines. These virtual machines live in the customer subscription where the Azure Virtual Desktop agent and agent bootloader are installed. The agent acts as the intermediate communicator between the service and the virtual machines, enabling connectivity. Therefore, if you're experiencing any issues with the agent installation, update, or configuration, your virtual machines won't be able to connect to the service. The agent bootloader is the executable that loads the agent.

This article will give you a brief overview of the agent installation and update processes.

Note

This documentation is not for the FSLogix agent or the Remote Desktop Client agent.

Initial installation process

The Azure Virtual Desktop agent is initially installed in one of two ways. If you provision virtual machines (VMs) in the Azure portal and Azure Marketplace, the agent and agent bootloader are automatically installed. If you provision VMs using PowerShell, you must manually download the agent and agent bootloader .msi files when creating an Azure Virtual Desktop host pool with PowerShell. Once the agent is installed, it installs the Azure Virtual Desktop side-by-side stack and Geneva Monitoring agent. The side-by-side stack component is required for users to securely establish reverse server-to-client connections. The Geneva Monitoring agent monitors the health of the agent. All three of these components are essential for end-to-end user connectivity to function properly.

Important

To successfully install the Azure Virtual Desktop agent, side-by-side stack, and Geneva Monitoring agent, you must unblock all the URLs listed in the Required URL list. Unblocking these URLs is required to use the Azure Virtual Desktop service.

Agent update process

The Azure Virtual Desktop service updates the agent whenever an update becomes available. Agent updates can include new functionality or fixes for previous issues. You must always have the latest stable version of the agent installed so your VMs don't lose connectivity or security. After you've installed the initial version of the Azure Virtual Desktop agent, the agent will regularly query the Azure Virtual Desktop service to determine if there’s a newer version of the agent, stack, or monitoring agent available. If a newer version exists, the updated component is automatically installed by the flighting system, unless you've configured the Scheduled Agent Updates feature. If you've already configured the Scheduled Agent Updates feature, the agent will only install the updated components during the maintenance window that you specify. For more information, see Scheduled Agent Updates.

New versions of the agent are deployed at regular intervals in five-day periods to all Azure subscriptions. These update periods are called "flights". It takes 24 hours for all VMs in a single broker region to receive the agent update in a flight. Because of this, when a flight happens, you may see VMs in your host pool receive the agent update at different times. Also, if the VMs are in different regions, they might update on different days in the five-day period. The flight will update all VM agents in all subscriptions by the end of the deployment period. The Azure Virtual Desktop flighting system enhances service reliability by ensuring the stability and quality of the agent update.

Other important things you should keep in mind:

  • The agent update isn't connected to Azure Virtual Desktop infrastructure build updates. When the Azure Virtual Desktop infrastructure updates, that doesn't mean that the agent has updated along with it.
  • Because VMs in your host pool may receive agent updates at different times, you'll need to be able to tell the difference between flighting issues and failed agent updates. If you go to the event logs for your VM at Event Viewer > Windows Logs > Application and see an event labeled "ID 3277," that means the Agent update didn't work. If you don't see that event, then the VM is in a different flight and will be updated later. See Set up diagnostics to monitor agent updates for more information about how to set up diagnostic logs to track updates and make sure they've been installed correctly.
  • When the Geneva Monitoring agent updates to the latest version, the old GenevaTask task is located and disabled before creating a new task for the new monitoring agent. The earlier version of the monitoring agent isn't deleted in case that the most recent version of the monitoring agent has a problem that requires reverting to the earlier version to fix. If the latest version has a problem, the old monitoring agent will be re-enabled to continue delivering monitoring data. All versions of the monitor that are earlier than the last one you installed before the update will be deleted from your VM.
  • Your VM keeps three versions of the agent and of the side-by-side stack at a time. This allows for quick recovery if something goes wrong with the update. The earliest version of the agent or stack is removed from the VM whenever the agent or stack updates. If you delete these components prematurely and the agent or stack has a failure, the agent or stack won't be able to roll back to an earlier version, which will put your VM in an unavailable state.

The agent update normally lasts 2-3 minutes on a new VM and shouldn't cause your VM to lose connection or shut down. This update process applies to both Azure Virtual Desktop (classic) and the latest version of Azure Virtual Desktop with Azure Resource Manager.

Next steps

Now that you have a better understanding of the Azure Virtual Desktop agent, here are some resources that might help you: