What is Nova? - Speaker Deck

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What is Nova? Intro to the OpenStack Compute Project Stephen Finucane (@stephenﬁn) Senior Software Engineer

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Stephen Finucane (@stephenﬁn) Senior Software Engineer

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Intro to Cloud and OpenStack Nova in OpenStack The Nova Services Random Stuff

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Why Cloud?

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I want a VM with this amount of RAM and storage running FooOS. ” “

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I want a VM with this amount of RAM and storage, connected to networks X and Y, running FooOS. ” “

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I want a VM with this amount of RAM and storage, connected to networks X and Y with a virtual baz device attached running FooOS. ” “

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Why OpenStack?

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Modular Scalable Production ready Open source Proven No vendor lock-in Hybrid cloud ...

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Nova in OpenStack

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I want a VM with this amount of RAM and storage, connected to networks X and Y with a virtual baz device attached running FooOS. ” “ 1 2 3 4

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The Services

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Broadly speaking, hosts running nova can be broken into control nodes and compute nodes Compute nodes are where VMs (“instances”) run and interact with other services for things like networking or storage Control nodes handle everything else, including API requests, choosing a compute node, managing access, … Anything more than a toy deployment will have multiple control nodes and many compute nodes

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nova-api Receive HTTP requests from users and other services nova-scheduler Determine which compute node to schedule an instance on; talks to placement nova-conductor Manages DB access on behalf of compute nodes and “conducts” long running tasks like live migration nova-compute Host and manage the lifecycle of instances

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nova-api-metadata Expose metadata that can be used by e.g. cloud-init; part of nova-api nova-novncproxy Provide a proxy for VNC consoles nova-serialproxy (unsupported in OSP) Provide a proxy for serial console nova-spicehtml5proxy (unsupported in OSP) Provide a proxy for SPICE console

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The Utilities

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nova relies on INI-based configuration files to configure individual services and flavors and image metadata to configure instances Most operations can be achieved via the RESTful API, but some management operations require a separate tool.

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nova-manage A collection of various admin-specific admin commands (admin only) nova-policy Inspect policy configuration (admin only) nova (novaclient) CLI for the nova API with some admin-only APIs openstack (openstackclient) Unified CLI for all OpenStack APIs; mostly end-user focused

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➡ API ➡ Conductor API validates request and passes it to the conductor Conductor ➡ Scheduler (➡ Placement) The scheduler requests allocation candidates (here, a compute node) from placement and then ﬁlters and weighs these to select one Conductor ⬅➡ Compute Instance is scheduled to host and compute takes over, building the instance and talking to other services (e.g. neutron) where necessary Fin.

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nova-api

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RESTful API Well, mostly. There are a couple of RPC’y APIs. Microversions Each change requires a new version (2.1, 2.2, …, 2.87). Support all microversions but some APIs will 404 No (more) proxy APIs or extensions Want networking? Talk to neutron. Ditto for storage etc. Documentation! docs.openstack.org/api-ref/compute

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nova-scheduler

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Filters and weighers Filters eliminate hosts and weighers set preferences Conﬁgurable Additional ﬁlters and weighers ✅ (but different schedulers ) Placement is king An authoritative resource tracker; VCPU, DISK_GB, MEMORY_MB, …

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nova-compute

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Highly conﬁgurable Simple VMs? ✅ Low-latency real-time VMs? ✅ VMs that make you sandwiches? Multiple hypervisors Supports libvirt (), Xen (☠), Hyper-V, VMWare, Ironic, PowerVM and ZVM Lots of server “actions” Reboot, rebuild, resize, (cold) migrate, live migrate, shelve/unshelve, ...

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More Stuff

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Cells (v2) Multiple conductors to help scale to 100s of nodes SR-IOV, PCI Passthrough, FPGAs, vGPUs, ... Yes, we support them. Cyborg is cool “I want this speciﬁc guest conﬁguration” Use RHEV/oVirt

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Using It

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$ openstack server create --flavor my-flavor --image my-image --network my-network my-server

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What is Nova? Intro to the OpenStack Compute Project Stephen Finucane (@stephenﬁn) Senior Software Engineer

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Credits Cover Photo by Billy Huynh Diver Photo by Jeremy Bishop Phone Mast Photo by Tony Stoddard

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Resources 2013 Red Hat Summit: OpenStack Architecture