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Components of a CAS Environment
Components of a CAS Environment
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Written by Fegeins Louis
Updated over 4 months ago

Overview

Cloud Automation Stack orchestrates the creation and management of Cloud VDI environments in Google Cloud. Each environment, called a deployment, consists of several key components that work together to deliver a rich end-user experience for remote computing. The article describes the components at a high level; comprehensive details can be found in Technical Reference section of our documentation.

itopia CAS supports two distinct deployment types:

  • Cloud VDI using Windows 10 Only - Deployments that are created to support Windows 10 only will provision custom services for itopia's Windows 10 desktop delivery.

  • Cloud VDI using Remote Desktop Services and Windows 10 - Deployments that are created to support both Remote Desktop Services (RDS) and Windows 10 will provision the necessary infrastructure for RDS as well as custom services for itopia's Windows 10 desktop delivery.

Core Components

At its most basic, a Cloud Desktop deployment consists of the following key components:

  • A Microsoft Active Directory domain

  • The VM instances that host users' Cloud VDI sessions, called Session Hosts. These are either Windows Server VM instances running the Remote Desktop Session Host role or Windows 10 Enterprise VMs.

  • VDI infrastructure for managing user sessions, using Microsoft's Remote Desktop Services stack (RD Broker, RD Licensing, and RD Web Access), itopia's custom broker stack (currently for Windows 10 Only deployments), or a combination of both

  • RD Gateway servers to provide secure, encrypted end-user connectivity to their VDI sessions using HTTPS

  • A network file share for storing user profiles and shared drive data

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Active Directory

Microsoft Active Directory is a identity and authentication platform (IdP/IAP) that is commonly used in Windows environments. Active Directory is a complex and powerful platform, but for the purposes of Cloud Desktop, it is used to store user account data and authenticate users when they log in. CAS also leverages Active Directory to apply group policy objects (GPOs) and perform some management activities such as using group membership to assign users to their respective Cloud Desktops.

Active Directory is a requirement for a CAS deployment. CAS offers several options for fulfilling this requirement; for more information, refer to Active Directory in CAS Deployments.

Remote Desktop Services Deployments

Remote Desktop Services (RDS) is a foundational pillar of itopia Cloud VDI. RDS enables multiple users to each have a dedicated, secure computing session on a single computer simultaneously. RDS also provides the underpinnings of certain CAS functionality such as Collection Pools and application publishing.

RDS has several distinct roles that must be present for the system to work; these roles are:

  • Remote Desktop Session Host - A Session Host is a server that runs Cloud Desktop sessions. When a user runs a Remote Desktop or RemoteApp, a Session Host is the server where the desktop or application is actually running; the desktop or application is "streamed" to the end-user's client device via the Remote Desktop Protocol (RDP), allowing them to interact with the session as it if was running on their local device.

  • Remote Desktop Session Broker - The Session Broker is the "brains" of an RDS environment. The Session Broker maintains the mapping of users to Session Hosts, monitors the status of Session Host servers, and routes users to the correct Session Host. The Session Broker also maintains the primary settings database for the RDS environment.

  • Remote Desktop Gateway - The RD Gateway role acts as a "proxy" device that provides a secure way of accessing Session Hosts, particularly across the public Internet. When a user accesses their Cloud Desktop, they actually connect to a Gateway server using encrypted HTTPS; the gateway server then creates a separate, encrypted connection to a Session Host and "relays" the input and output between the end-user and their Cloud Desktop session. In this way, access to the internal network is extremely limited, and user sessions are protected via TLS when traversing the Internet.

  • Remote Desktop Web - The RD Web role provides a browser-accessible web portal where users can log in to launch their RDS desktops and applications. The RD Web role also hosts the Remote Desktop Web Client, an HTML5 RDP client that allows users to access their Cloud Desktops directly from a web browser

  • Remote Desktop Licensing - The RD Licensing role tracks the usage of Remote Desktop Subscriber Access Licenses (RDS SALs) in the environment.

CAS offers several predefined deployment types that configure these roles in different configurations, or administrators can create an Advanced deployment that allows full configuration of each role.

Windows 10 Only Deployments

For environments where Remote Desktop Services (RDS) is not required or desired, CAS also supports Windows 10 Only deployments. These deployments do not configure the full RDS stack described above and, instead, only leverage the RD Gateway role to provide secure, HTTPS-based connectivity to users' Cloud VDI sessions.

  • CAS Ledger Service - The CAS Ledger Service monitors user session status on Windows 10 Session Hosts and routes users to the appropriate Session Host when they connect from the Cloud VDI Portal

  • Remote Desktop Gateway - In a Windows 10 Only deployment, the RD Gateway role is deployed as a standalone role on one or more servers in each GCP region. This role acts as a "proxy" device that provides a secure way of accessing Session Hosts, particularly across the public Internet. When a user accesses their Cloud Desktop, they actually connect to a Gateway server using encrypted HTTPS; the gateway server then creates a separate, encrypted connection to a Session Host and "relays" the input and output between the end-user and their Cloud Desktop session. In this way, access to the internal network is extremely limited, and user sessions are protected via TLS when traversing the Internet.

  • Cloud VDI Portal - The Cloud VDI portal is a web-based method for users to access their Cloud VDI sessions. Users log into Cloud VDI with their Active Directory credentials; the credentials are securely proxied to the RD Gateway server(s) in the Cloud VDI environment, which then performs Active Directory authentication of the user's credentials and assigns a short-lived token for the user to view and access their Cloud VDI resources (published Remote Desktops and RemoteApps). When a user connects to their resource, the portal downloads a customized RDP file that is launched using the Remote Desktop client on the user's local device.

  • Windows 10 Session Hosts - Windows 10 Only deployments necessitate the use of Windows 10 Session Hosts. These Session Hosts must run Windows 10 Enterprise on Google Cloud sole-tenant nodes, and support only a single concurrent user session.

Network File Share

CAS deployments rely on a network file share to store users' roaming profiles and shared network drives created via the CAS console. In order to create a CAS deployment, an SMB file share must be available. CAS offers several options for satisfying this requirement, including:

  • Dedicated Windows File Server - CAS can create a standalone Windows File Server with an expandable data drive that is automatically configured with secure network shares for user profiles and shared drives

  • NetApp Cloud Volume Service - NetApp offers a managed solution for providing high-performance, maintenance-free SMB file shares in many Google Cloud regions.

  • Shared Drive on a Session Host - For small deployments, CAS can configure the network file share role on a Session Host, although performance and scalability are slightly reduced

Supporting Components

Depending on the configuration of your deployment, CAS will create and configure several other components in your GCP project. A more comprehensive list of deployment resources is available in the Technical Reference section of the documentation, but the following list provides an overview of several key components that may be part of your deployment.

  • Google Cloud Load Balancer - If you deploy redundant RD Gateway servers, CAS will create an Internet-facing GCP load balancer instance for the RD Gateways in each region. The load balancer will be enabled for HTTPS traffic and will be configured as the connection point for your end-users

  • Microsoft SQL Server - If you deploy redundant RD Broker servers, CAS will create a Google Cloud SQL instance in your GCP project. A SQL instance is required to host the Connection Broker Database when the RD Broker is configured for high availability. Cloud SQL provides a cost-effective, highly-available, secure managed SQL instance for supporting RD Broker high availability.NOTE: CAS deployments created prior to January 2021 used a traditional SQL Server cluster using Windows VM instances.

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