OpenNebula

OpenNebula Overview

OpenNebula is an open-source cloud computing platform designed to manage heterogeneous data center, public cloud, and edge computing infrastructure. It provides a unified framework for orchestrating virtualized workloads across hybrid environments, supporting multi-tenancy, self-service provisioning, and integration with existing enterprise systems. Licensed under the Apache License 2.0, OpenNebula serves as a flexible solution for building private, public, or hybrid clouds while maintaining compatibility with diverse hypervisors and storage backends.

Core Architecture and Components

The platform’s architecture revolves around a front-end node (cloud management cluster) and hypervisor-enabled hosts (worker nodes). The front-end runs critical services like the OpenNebula Daemon (oned), scheduler (mm_sched), and monitoring subsystems (onemonitord), which orchestrate VM lifecycle operations, resource allocation, and health checks. Worker nodes leverage hypervisors such as KVM, VMware, or Xen to execute virtual machines, with clusters sharing datastores and virtual networks for unified resource pooling.

Hypervisor and Virtual Machine Management

OpenNebula natively supports KVM as its default hypervisor, while offering plugins for VMware vCenter, Xen, and LXD containers. Virtual machines are defined through templates that specify CPU, memory, disk images, and network configurations. Each VM instance maintains its own lifecycle, enabling multiple deployments from a single template. Live migration and snapshotting ensure workload portability and state preservation across hosts.

High Availability and Fault Tolerance

The front-end achieves high availability through a Raft-based consensus protocol, electing a leader node to coordinate write operations across multiple management servers. This design tolerates failures of up to n-1/2 nodes in an n-node cluster, ensuring continuous operation during hardware outages. For workloads, VM high availability is enforced by automatically restarting instances on healthy hosts, while storage redundancy is achieved via distributed systems like Ceph or StorPool.

Networking and Virtual Infrastructure

Virtual networks in OpenNebula abstract underlying physical infrastructure, supporting VLANs, security groups, and dual-stack IPv4/IPv6 configurations. The platform integrates with SDN solutions like Open vSwitch and offers a Virtual Router appliance for DHCP, DNS, and NAT services. Multi-tier applications benefit from isolated network segments and load-balancing rules defined through the web interface or API.

Storage Integration and Performance

OpenNebula interfaces with block storage (iSCSI, Fibre Channel), file-based systems (NFS, GlusterFS), and distributed storage (Ceph, StorPool). The Hyperconverged Architecture combines compute and storage roles on the same nodes, leveraging StorPool’s synchronous replication and thin provisioning for low-latency VM disk operations. Raw disk formats bypass filesystem overhead, maximizing I/O throughput for database and AI workloads.

Multi-Tenancy and Self-Service

Role-based access control (RBAC) enables granular permission assignment across Virtual Data Centers (VDCs), projects, and user groups. The self-service portal allows end-users to deploy preconfigured VM templates, manage quotas, and monitor consumption. Contextualization tools like cloud-init automate post-deployment configuration, including SSH key injection and network settings.

Edge and Hybrid Cloud Capabilities

The Edge Cluster Provisioning module integrates geographically distributed clusters using Terraform and Ansible, enabling centralized management of edge nodes. Cloud Bursting dynamically extends workloads to public clouds like AWS or Azure during peak demand, while federation features synchronize resources across multiple OpenNebula instances.

Ecosystem and Automation

OpenNebula’s RESTful API and CLI tools (onecli) facilitate integration with DevOps pipelines, Terraform, and Kubernetes. The platform supports containerized workloads through LXD and Docker, with Longhorn providing persistent storage for stateful applications. Customizable hooks and webhooks trigger automated responses to events like VM creation or host failure.

Use Cases and Enterprise Adoption

Organizations deploy OpenNebula for hyperconverged private clouds, combining StorPool’s distributed storage with KVM hypervisors for high-density VM hosting. Research institutions leverage edge clustering for distributed data processing, while enterprises utilize hybrid cloud bursting for cost-effective scalability. The platform’s compatibility with legacy VMware environments simplifies migration paths for organizations transitioning to open-source solutions.

Tool Link: https://opennebula.io/