Azure Virtual Machine Scale Sets (VMSS) is a service that enables you to create and manage a group of load-balanced, identical virtual machines (VMs) to support large-scale, compute-intensive, and stateless workloads. VM Scale Sets automatically scale the number of VM instances based on performance metrics or predefined schedules, ensuring that your applications can handle varying loads while optimizing resource usage and cost. Here's an overview of Azure VM Scale Sets:
VM Scale Sets allow you to scale the number of VM instances in response to changes in demand or based on a predefined schedule. You can configure auto-scaling rules based on performance metrics (e.g., CPU utilization) or time-based schedules, and VM Scale Sets will automatically add or remove VM instances as needed.
VM Scale Sets distribute VM instances across multiple fault domains and update domains within an Azure availability set or across availability zones. This helps to minimize the impact of hardware failures, planned maintenance, and updates on your applications, ensuring high availability and fault tolerance.
VM Scale Sets integrate with Azure Load Balancer and Azure Application Gateway to distribute incoming network traffic evenly across the VM instances. This ensures that your applications can handle large amounts of traffic and provide consistent performance to users.
VM Scale Sets are designed for stateless applications, where each VM instance can be treated as interchangeable and no instance-specific state is maintained. This allows you to easily scale out and in, as well as to perform rolling updates without affecting the overall application state.
VM Scale Sets use instance templates to define the configuration of the VM instances, such as the VM size, OS image, data disks, and network settings. You can create custom VM images or use pre-built images from the Azure Marketplace. Instance templates also support the use of custom scripts or extensions to configure the VM instances during deployment.
VM Scale Sets enable you to perform rolling updates of the VM instances without downtime. You can update the instance template with a new VM image or configuration, and VM Scale Sets will automatically update the existing instances in a controlled manner, ensuring that your application remains available during the update process.
VM Scale Sets integrate with various Azure services, such as Azure Monitor for logging and monitoring, Azure Security Center for security and compliance, and Azure DevOps for continuous integration and deployment.
Azure provides SDKs for popular programming languages and a REST API for managing VM Scale Sets programmatically. This allows you to integrate VM Scale Sets with your existing applications, workflows, and tools.