nova/doc/source/reference/index.rst

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Technical Reference Deep Dives

The nova project is large, and there are lots of complicated parts in it where it helps to have an overview to understand how the internals of a particular part work.

Internals

The following is a dive into some of the internals in nova.

  • /reference/rpc: How nova uses AMQP as an RPC transport
  • /reference/scheduling: The workflow through the scheduling process
  • /reference/scheduler-hints-vs-flavor-extra-specs: The similarities and differences between flavor extra specs and scheduler hints.
  • /reference/live-migration: The live migration flow
  • /reference/services: Module descriptions for some of the key modules used in starting / running services
  • /reference/vm-states: Cheat sheet for understanding the life cycle of compute instances
  • /reference/threading: The concurrency model used in nova, which is based on eventlet, and may not be familiar to everyone.
  • /reference/notifications: How the notifications subsystem works in nova, and considerations when adding notifications.
  • /reference/update-provider-tree: A detailed explanation of the ComputeDriver.update_provider_tree method.
  • /reference/upgrade-checks: A guide to writing automated upgrade checks.
  • /reference/conductor

Need something about versioned objects and how they fit in with conductor as an object backporter during upgrades.

  • /reference/isolate-aggregates: Describes how the placement filter works in nova to isolate groups of hosts.
  • /reference/attach-volume: Describes the attach volume flow, using the libvirt virt driver as an example.
  • /reference/block-device-structs: Block Device Data Structures
  • /reference/libvirt-distro-support-matrix: Libvirt virt driver OS distribution support matrix

rpc scheduling scheduler-hints-vs-flavor-extra-specs live-migration services vm-states threading notifications update-provider-tree upgrade-checks conductor isolate-aggregates api-microversion-history attach-volume block-device-structs libvirt-distro-support-matrix

Debugging

  • /reference/gmr: Inspired by Amiga, a way to trigger a very comprehensive dump of a running service for deep debugging.

gmr

Forward Looking 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 "Internals" 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.

  • /user/cells: How cells v2 is evolving
  • /reference/policy-enforcement: How we want policy checks on API actions to work in the future
  • /reference/stable-api: What stable api means to nova
  • /reference/scheduler-evolution: Motivation behind the scheduler / placement evolution

/user/cells policy-enforcement stable-api scheduler-evolution

Additional Information

  • /reference/glossary: A quick reference guide to some of the terms you might encounter working on or using nova.

glossary