This example scenario describes a high-availability solution for a jump server that runs on Azure. It uses an open-source tool called Apache Guacamole, which has functionality that's like that of Azure Bastion.
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The architecture includes a public load balancer that receives external access requests and directs them to two virtual machines (VMs) in the web layer. The web layer communicates with the data layer, where a MySQL database stores sign-in information, access events, and connections.
Download a Visio file of this architecture.
- A user initiates a connection over the internet.
- The connection from the user is established with the Azure public load balancer.
- The Azure public load balancer receives external access and directs the traffic for the two VMs in the web tier.
- The web tier communicates with Azure Database for MySQL in the data tier. This database stores sign-in information, access events, and connections.
- The connection is established with the target clients via Secure Shell (SSH), Virtual Network Computing (VNC), or Remote Desktop Protocol (RDP) protocol.
- Azure Load Balancer: A service for distributing load (incoming network traffic) across a group of back-end resources or servers.
- Azure Virtual Network: The fundamental building block for your private network on Azure.
- Public IP addresses: A service that allows internet resources to communicate inbound to Azure resources.
- Azure DDoS Protection, combined with application-design best practices, provides enhanced DDoS mitigation features to provide more defense against DDoS attacks. You should enable Azure DDOS Protection on any perimeter virtual network.
- Network security groups: A service that filters network traffic traveling to and from Azure resources in an Azure virtual network.
- Availability set: A logical grouping of VMs that allows Azure to provide redundancy and availability.
- Azure Database for MySQL: A fully managed MySQL database as a service.
If you don't need as much control as the solution described here provides, you can use Azure Bastion, a fully managed service that offers high-security RDP and SSH access to VMs without any exposure through public IP addresses.
Apache Guacamole is a clientless remote desktop gateway that supports standard protocols like VNC, RDP, and SSH. Because it's clientless, your users don't need to install anything. They just use a web browser to remotely access your VMs.
For more information about Guacamole and its internal components, see Implementation and architecture.
To provide high availability, this solution:
- Uses availability sets for VMs. For service-level agreements (SLAs), see SLAs for Virtual Machines.
- Uses Azure Database for MySQL, a high-availability, scalable, managed database. For SLAs, see SLAs for Azure Database for MySQL.
The solution also uses:
- Load Balancer.
- VMs with NGINX as a reverse proxy.
- Tomcat as an application service.
- Certbot to get free Secure Sockets Layer (SSL) certificates from Let's Encrypt.
Potential use cases
- Access your computers from any device. Because Guacamole requires only a reasonably fast standards-compliant browser, it runs on many devices, including mobile phones and tablets.
- Host a computer in the cloud. Computers hosted on virtualized hardware are more resilient to failures. With the current availability of on-demand computing resources, Guacamole is a perfect way to access machines that are accessible only over the internet.
- Provide easy access to a group of people. You can use Guacamole to centralize access to a large group of machines and specify on a per-user basis which machines can be accessed. Rather than remember a list of machines and credentials, users only need to sign in to a central server and select one of the listed connections.
- Add HTML5 remote access to your existing infrastructure. Because Guacamole is an API and not just a web application, you can use the core components and libraries provided by the Guacamole project to add HTML5 remote access features to an existing application. You don't need to use the main Guacamole web application. You can write or integrate with your own applications fairly easily.
These considerations implement the pillars of the Azure Well-Architected Framework, which is a set of guiding tenets that you can use to improve the quality of a workload. For more information, see Microsoft Azure Well-Architected Framework.
Reliability ensures your application can meet the commitments you make to your customers. For more information, see Overview of the reliability pillar.
This solution's resiliency depends on the failure modes of individual services like Azure Virtual Machines, Azure Database for MySQL, and Azure Load Balancer. For more information, see these articles:
For information about disaster recovery, see Business continuity and disaster recovery.
For Azure VMs in the web tier, you can use availability sets to create a logical grouping of VMs that provides redundancy and availability. We recommend at least two VMs per availability set to create a high-availability application and meet the Azure SLA.
Because Azure Database for MySQL is a managed database as a service, its architecture is optimized for built-in high availability. For information about SLAs, see SLAs for Azure Database for MySQL.
Security provides assurances against deliberate attacks and the abuse of your valuable data and systems. For more information, see Overview of the security pillar.
You might want to add Azure Web Application Firewall to this solution. It helps protect your application from common vulnerabilities. This Azure Application Gateway option uses Open Web Application Security Project (OWASP) rules to help prevent attacks like cross-site scripting, session hijacking, and other exploits.
As an added layer of protection, be sure to use Azure network security groups to filter network traffic traveling to and from Azure resources in the Azure virtual network.
You should also consider Private Link for Azure Database for MySQL. You can use Private Link to connect to platform as a service (PaaS) services in Azure via a private endpoint. Private Link essentially brings Azure services inside your private virtual network. PaaS resources can be accessed via the private IP address just like any other resource in the virtual network.
Finally, follow these security guidelines when you implement this solution.
Cost optimization is about finding ways to reduce unnecessary expenses and improve operational efficiencies. For more information, see Overview of the cost optimization pillar.
To better understand the cost of running this scenario on Azure, use the pricing calculator.
For more information about the cost of this solution, see:
- Linux Virtual Machines pricing
- Azure Database for MySQL pricing
- Load Balancer pricing
- Azure Reserved Virtual Machine Instances
Operational excellence covers the operations processes that deploy an application and keep it running in production. For more information, see Overview of the operational excellence pillar.
Operational excellence applies reliability, predictability, and automated operations to your architecture to keep your application running in production. Deployments must be reliable and predictable. Automated deployments reduce the chance of human error.
Implement software engineering disciplines across your entire environment, including these practices:
- Implement Infrastructure as Code.
- Build and release with continuous integration and continuous delivery (CI/CD) pipelines.
- Use automated testing.
For more information, see Operational excellence design principles.
Performance efficiency is the ability of your workload to scale to meet the demands placed on it by users in an efficient manner. For more information, see Performance efficiency pillar overview.
To accomplish this goal, consider using Azure Virtual Machine Scale Sets, which you can use to create and manage a group of load-balanced VMs. The number of VM instances can automatically increase or decrease in response to demand or according to a defined schedule.
Deploy this scenario
For deployment steps, see Deploying Apache Guacamole on Azure.
This article is maintained by Microsoft. It was originally written by the following contributors.
- Ricardo Macedo Martins | Sr. Customer Engineer
- Mick Alberts | Technical Writer
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- Apache Guacamole documentation
- Azure Bastion documentation
- What is Azure Load Balancer?
- Azure Database for MySQL
- Learn module: Introduction to Azure Bastion
- Learn module: Introduction to Azure Load Balancer