CloudStack

CloudStack is an open-source cloud computing software platform that enables the creation, management, and provisioning of cloud services in public, private, and hybrid environments. It provides an infrastructure as a service (IaaS) stack for deploying and operating large networks of virtual machines and related resources.

The project originated as Cloud.com, was acquired by Citrix in 2011, and was donated to the Apache Software Foundation in 2012, where it has been developed as Apache CloudStack under the Apache License 2.0. It is maintained by a community of contributors and corporate sponsors and is used by a number of service providers and enterprise clouds.

CloudStack follows a centralized management model. A central management server coordinates resources across one or more zones. Each zone contains one or more pods, clusters, hosts, primary storage, and secondary storage. Users and administrators interact with the stack via a web-based self-service portal, a RESTful API, or command-line tools. The platform abstracts underlying hypervisors and supports multiple virtualization technologies through driver integrations. Supported hypervisors include KVM, VMware vSphere, and XenServer, with additional drivers available in some deployments. Networking features cover virtual networks, VLANs, firewall and DNAT rules, VPN connectivity, and load balancing; the platform also provides SDN capabilities and integrates with storage options such as primary storage for VMs and secondary storage for templates, ISO images, and backups.

Key capabilities include service offerings for compute and storage, template and ISO management, security groups, dynamic routing, auto-scaling, and monitoring alarms. As an Apache project, CloudStack is free under open-source terms and is designed to operate at scale in provider and enterprise environments.