Cozystack and OpenStack are both open-source, Apache 2.0 private cloud platforms used to run virtual machines, containers, and storage on owned hardware. They differ in generation and operational footprint: OpenStack is a multi-project stack (Nova, Neutron, Cinder, Keystone) typically requiring 50 to 100 or more coordinated services, while Cozystack is built on a single Kubernetes API with KubeVirt for VMs, Cilium (eBPF) for networking, and LINSTOR/DRBD for storage, running roughly 5 to 15 operators. OpenStack suits large telco, government, and OpenStack-fluent teams; Cozystack suits service providers, regulated multi-tenant workloads, and modern greenfield builds. Aenix, the team behind the CNCF project Cozystack, sells the productized Ænix Platform plus migration services for teams modernizing away from OpenStack.
Both are open-source private cloud platforms. Both Apache 2.0. Both production-proven. The difference is generation and operational footprint.
Pairs with: Ænix Public Cloud Platform — hosting providers modernizing from OpenStack, and large operators consolidating OpenStack onto a multi-region control plane.
| OpenStack | Cozystack |
|---|
| License | Apache 2.0 | Apache 2.0 |
| Foundation | Multi-project (Nova, Neutron, Cinder, etc.) | Kubernetes + KubeVirt + Cilium |
| Operational footprint | 50-100+ service processes across a dozen projects | 5-15 Kubernetes operators |
| Engineer availability | Specialist, and hard to hire in most markets | Kubernetes-large |
| Multi-tenancy | Keystone projects | Tenant CRD |
| Modernization path | Major-version upgrades | Kubernetes-standard rolling |
| Best for | Large telco / government / OpenStack-fluent | Service providers, regulated multi-tenant, modern greenfield |
Where OpenStack is genuinely better
The table above compares operational footprint, which flatters Cozystack. Breadth is the axis where OpenStack wins outright, and for some estates it is the axis that decides:
- Ironic. Mature bare-metal provisioning as a first-class cloud service, with inspection, cleaning and RAID configuration. Cozystack has no equivalent. If you sell bare metal, this alone can settle the question.
- The rest of the service surface. Octavia for load balancing as a tenant API, Manila for shared filesystems, Barbican for key management, Designate for DNS, Swift for object storage with its own long-lived semantics. Each is a project someone maintains; a Kubernetes-native platform reaches some of those outcomes with different primitives and does not reach others at all.
- Telco and NFV. SR-IOV, DPDK, huge pages, CPU pinning and NUMA-aware placement have been production-hardened in Nova for years, and VNF vendors certify against OpenStack. That certification matters more than the technology.
- Scale evidence and vendor choice. Fifteen years of public deployments at six-figure core counts, and a real choice of commercially supported distributions. Cozystack is younger, and honest evaluation should weigh that.
- An API a decade of tooling already speaks. If your customers hold OpenStack credentials and automate against your endpoints, moving is a public API deprecation, not an infrastructure project.
If you have a staffed team, an exercised upgrade path, and real use of that wider surface, stay on OpenStack. The Cozystack case is operational — footprint and staffing — not technical superiority.
See OpenStack alternative for when that case applies and OpenStack migration for the service-by-service mapping.
Ænix is the team behind Cozystack.
Frequently asked questions
Is Cozystack a drop-in replacement for OpenStack?
No, and in places it is narrower. Cozystack is built on Kubernetes, KubeVirt and Cilium rather than the Nova/Neutron/Cinder model, so it is suited to greenfield builds or modernization rather than a like-for-like component swap. It also has no Ironic equivalent for bare-metal provisioning, and Octavia, Manila, Barbican and Designate map onto different primitives or onto nothing. Teams with deep OpenStack expertise running stable clusters should keep OpenStack.
Why would a team move from OpenStack to Cozystack?
The most common trigger is staffing: OpenStack operators are specialists and hard to hire in most markets, while Kubernetes skills are abundant. Cozystack also cuts operational footprint from 50 to 100-plus service processes down to roughly 5 to 15 operators, and uses Kubernetes-standard rolling updates instead of major-version OpenStack upgrades. This is an operational case, not a claim that OpenStack is technically inferior.
Are both platforms really free of licensing fees?
Yes. Both Cozystack and OpenStack are licensed under Apache 2.0 with no per-CPU or per-core licensing. Aenix charges only for the productized Ænix Platform and services, not for the underlying open-source software.
How does multi-tenancy differ between the two?
OpenStack isolates tenants through Keystone projects. Cozystack uses a native Tenant CRD on the Kubernetes API, giving each tenant isolated resources managed declaratively through standard Kubernetes tooling.
Can Cozystack run virtual machines like OpenStack does?
Yes. Cozystack runs VMs through KubeVirt and containers through Kubernetes on a single API, so virtual machines and containers share the same control plane, networking (Cilium/eBPF), and storage (LINSTOR/DRBD).
Who supports a Cozystack migration from OpenStack?
Aenix, the team behind the CNCF project Cozystack, offers the Ænix Platform plus migration services. Public Cloud Platform covers both cases: hosting providers modernizing off OpenStack, and large operators consolidating OpenStack at scale with a multi-region control plane.
