**OpenStack** is the most widely deployed open source cloud infrastructure platform. It provides a complete IaaS (Infrastructure as a Service) layer — turning a pool of bare metal servers into a tenant-facing cloud with compute, networking, storage, and identity services. OVHcloud, CERN, Walmart, and dozens of telecom providers run it in production. --- ### First Principle: A cloud is just an API in front of physical resources. OpenStack is that API. Every OpenStack component maps to an AWS equivalent. The difference is you control the entire stack — every config file, every database, every line of code. That's both the power and the operational burden. --- ### Key Considerations - **Core Services**: Nova (compute/EC2), Neutron (networking/VPC), Cinder (block storage/EBS), Swift (object storage/S3), Keystone (identity/IAM), Horizon (dashboard), Heat (orchestration/CloudFormation), Ironic (bare metal). - **Compute Driver**: Nova uses [[libvirt]] to call [[KVM]] for VM creation. Ironic bypasses virtualisation to provision [[Bare Metal]] directly. - **Networking**: Neutron with [[OVN]] or [[Open vSwitch (OVS)]] provides tenant-isolated virtual networks, floating IPs, and security groups. - **Storage**: Cinder typically backends to [[Ceph]] RBD for block volumes. Swift or [[MinIO]] handles object storage. - **Operational Complexity**: OpenStack has many moving parts. Tools like [[Ansible]]-based OpenStack-Ansible automate deployment and upgrades. - **Scale**: Used at CERN for 300,000+ cores. Battle-tested at genuine hyperscaler scale. --- ### How It Fits ``` [[MAAS]] provisions bare metal → OpenStack orchestrates it into a cloud → [[KVM]] / [[libvirt]] handle VM execution → [[Ceph]] / [[OVN]] handle storage / networking → [[Keycloak]] / Keystone handle identity ``` [[KVM]] | [[libvirt]] | [[Ceph]] | [[OVN]] | [[Keycloak]] | [[Open Source Hyperscaler MoC]]