With OpenStack making significant inroads into data centers worldwide, the most recent version, codenamed Liberty, could be the linchpin in bringing the technology to an even wider audience. Liberty addresses key issues that have limited the appeal of previous OpenStack versions for broad-scale enterprise use. In particular, huge improvements in virtualization will make software-defined networking (SDN) and network-functions virtualization (NFV) much simpler to deploy.

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The new release includes more than 50 notable enhancements over the predecessor, Kilo, but the biggest improvements for data center IT are to the Nova virtualized compute component, with scaling improvements in Cells v2, and the first full release of management support for containers. Overall, the changes that will have the greatest impact can be broken down into scalability, manageability and extensibility.


With the introduction of Cells v2, an upgrade that makes using the cell model much simpler, enhanced scalability becomes a basic component of the OpenStack architecture. With the cell model, hosts are configured into groups in a tree structure. In v2, the cells are now horizontally scalable, allowing large organizations that use multiple small OpenStack installations to maintain consistency across all of those installations. Fundamentally, this means that larger OpenStack deployments will be possible because resources can be grouped together and managed more easily.

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With sufficiently fast network connections, administrators will be able to treat multiple NFV instances (or any SDN or NFV instance or application that is supported by the OpenStack infrastructure) as if they were a single local cloud, when they could actually be scattered across the globe. You also now have the option of adding additional servers to a cell to increase capacity rather than only being able to migrate to larger servers to achieve the same result in capacity enhancement.

With the addition of NFV in Liberty, organizations that are currently making, or have been planning on making, heavy use of NFV will see a significant enhancement in their capabilities in deploying and managing these virtualized instances. This also makes OpenStack and NFV more tightly integrated and will encourage the development of an NFV architecture on top of the OpenStack layer, which will offer greater flexibility in building these higher-level systems on the standardized OpenStack layer.

Organizations with a heavy commitment to SDN will be able to run both SDN and NFV infrastructures from the OpenStack deployment.

Both Nova, the fabric controller for the OpenStack cloud computing environment, and Neutron, the SDN component for virtual compute environments, are impacted by the scalability improvements in Liberty. Certain aspects of the underlying architecture and new and improved features in the Liberty release enable higher-level functionality that affects many different aspects of OpenStack. It is basically impossible to completely separate the networking and management improvements that are combined to provide an overall better experience for administrators, both in actual improvements in capabilities and in better exposing functionality in a way that it can be more easily accessed and utilized.


A significant number of the changes in Liberty relate directly to management – from common library adoption to simplified management features and finer-grained access controls. Much comment has been made on the future needs of the orchestration components of OpenStack, moving to a converged model that better fits the needs of users. In Liberty, changes discussed for future versions in features such as workflow have been implemented in the current version of Heat, the OpenStack orchestration project. There is also an optional mode for persistent per-resource state during stack updates. This makes the procedure more fault-tolerant and a failure of the orchestration engine during operations can be made recoverable.

Two new features in Liberty will make OpenStack much more appealing to multi-tenant data center operators. The first is role-based access control (RBAC). With RBAC the previous public/private networking options found in OpenStack, where a network was shared by all or was not shared at all, has been replaced with the ability to use fine-grained permissions for sharing networks. Specific sets of tenants can be allowed to attach to specific networks, or can be limited to pre-assigned networks.

The release of Liberty is the first under the Big Tent model. Under this process, a large number of projects is being included as part of the coordinated release.

The second is an extensible API-enabling detailed control over quality-of-service (QoS). The reference implementation allows for QoS on a per-port and per-network basis. This means bandwidth can be assigned based on availability or application demands, and on a dynamic basis, as configured by the administrator.

Liberty also includes the first full release of the Magnum project, which is designed to improve the manageability of containers by supporting Docker Swarm, Mesos and Google’s container management program, Kubernetes. By making use of Heat orchestration with the container management programs, VM instances can be deployed to either existing servers or bare metal. The Kolla project, included in Liberty, supports Docker image building of more than 90 containers of OpenStack using the most popular Linux distributions.

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– Thinkstock / novaaleksandra


The release of Liberty is the first under the Big Tent model. Under this process, a large number of projects is being included as part of the coordinated release. The OpenStack platform will continue to be a focus for multiple technology projects which, as in many open-source driven models, will adapt and support both vertical and horizontal development as technologies driven by vendor interest are supported on OpenStack. And as a wider user base becomes drawn to the technologies, successful ones will find a broader appeal and may find themselves incorporated under the Big Tent to be updated and released alongside the latest versions of the core components. Projects that wish to be included must meet a set of requirements.

Even though the top Liberty code committers were HP, Red Hat, Mirantis, IBM, Rackspace, Huawei, Intel, Cisco, VMware and NEC, there were contributions from more than 2,100 individuals representing more than 160 organizations to the more than 25,000 commits to the Liberty release. This indicates a significant breadth of interest and commitment to OpenStack well beyond the name brand supporters.

Even though the Liberty release came only six months after the Kilo release, the changes and improvements, especially from the perspective of commercial data center operators, are significant. With the improvements in manageability and networking, the Liberty release, in the minds of many, might be the turning point to even broader adoption of the OpenStack platform.

This article appeared in the March issue of DatacenterDynamics magazine