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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: The notifications available in nova./reference/update-provider-tree: A detailed explanation of theComputeDriver.update_provider_treemethod./reference/upgrade-checks: A guide to writing automated upgrade checks./reference/database-migrations: A guide to writing database migrations, be they online or offline./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 database-migrations 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.
/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
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