Welcome to Nova’s developer documentation!¶
Nova is an OpenStack project designed to provide power massively scalable, on demand, self service access to compute resources.
The developer documentation provided here is continually kept up-to-date based on the latest code, and may not represent the state of the project at any specific prior release.
This is documentation for developers, if you are looking for more general documentation including API, install, operator and user guides see docs.openstack.org
This documentation is intended to help explain what the Nova developers think is the current scope of the Nova project, as well as the architectural decisions we have made in order to support that scope. We also document our plans for evolving our architecture over time. Finally, we documented our current development process and policies.
Compute API References¶
The Nova compute API is quite large, we provide a concept guide which gives some of the high level details, as well as a more detailed API reference.
The API reference covers all versions of the API. Version 2.0 and Version 2.1 are actually the same API, and Version 2.1 evolves forward with microversions. The API ref starts with the base API version, and specifies all changes that exist to it as microversions roll forward. You can also see a history of our microversions here:
Only Version 2.1 APIs should be used from this point forward, Version 2.0 APIs are only provided for backward compatibility purposes.
There was a session on the v2.1 API at the Liberty summit which you can watch here.
Nova aims to have a single compute API that works the same across all deployments of Nova. While many features are well-tested, well-documented, support live upgrade, and are ready for production, some are not. Also the choice of underlying technology affects the list of features that are ready for production.
Our first attempt to communicate this is the feature support matrix (previously called the hypervisor support matrix). Over time we hope to evolve that to include a classification of each feature’s maturity and exactly what technology combinations are covered by current integration testing efforts.
If you are new to Nova, this should help you start to understand what Nova actually does, and why.
The Nova community is a large community. We have lots of users, and they all have a lot of expectations around upgrade and backwards compatibility. For example, having a good stable API, with discoverable versions and capabilities is important for maintaining the strong ecosystem around Nova.
Our process is always evolving, just as Nova and the community around Nova evolves over time. If there are things that seem strange, or you have ideas on how to improve things, please engage in that debate, so we continue to improve how the Nova community operates.
This section looks at the processes and why. The main aim behind all the process is to aid good communication between all members of the Nova community, while keeping users happy and keeping developers productive.
This follows on for the discussion in the introduction, and digs into details on specific parts of the Nova architecture.
We find it important to document the reasons behind our architectural decisions, so its easier for people to engage in the debates about the future of Nova’s architecture. This is all part of Open Design and Open Development.
- Adding a Method to the OpenStack API
- AMQP and Nova
- Block Device Mapping in Nova
- Conductor as a place for orchestrating tasks
- Filter Scheduler
- Host Aggregates
- Notifications in Nova
- Placement API
- Placement API Developer Notes
- Threading model
- Virtual Machine States and Transitions
Architecture Evolution Plans¶
The following section includes documents that describe the overall plan behind groups of nova-specs. Most of these cover items relating to the evolution of various parts of Nova’s architecture. Once the work is complete, these documents will move into the “Concepts” section. If you want to get involved in shaping the future of Nova’s architecture, these are a great place to start reading up on the current plans.