nova/doc/source/admin/index.rst

Admin Documentation

The OpenStack Compute service allows you to control an Infrastructure-as-a-Service (IaaS) cloud computing platform. It gives you control over instances and networks, and allows you to manage access to the cloud through users and projects.

Compute does not include virtualization software. Instead, it defines drivers that interact with underlying virtualization mechanisms that run on your host operating system, and exposes functionality over a web-based API.

Overview

To effectively administer compute, you must understand how the different installed nodes interact with each other. Compute can be installed in many different ways using multiple servers, but generally multiple compute nodes control the virtual servers and a cloud controller node contains the remaining Compute services.

The Compute cloud works using a series of daemon processes named nova-* that exist persistently on the host machine. These binaries can all run on the same machine or be spread out on multiple boxes in a large deployment. The responsibilities of services and drivers are:

Services

nova-api-metadata </cli/nova-api-metadata>

A server daemon that serves the Nova Metadata API.

nova-api-os-compute </cli/nova-api-os-compute>

A server daemon that serves the Nova OpenStack Compute API.

nova-api </cli/nova-api>

A server daemon that serves the metadata and compute APIs in separate greenthreads.

nova-compute </cli/nova-compute>

Manages virtual machines. Loads a Service object, and exposes the public methods on ComputeManager through a Remote Procedure Call (RPC).

nova-conductor </cli/nova-conductor>

Provides database-access support for compute nodes (thereby reducing security risks).

nova-scheduler </cli/nova-scheduler>

Dispatches requests for new virtual machines to the correct node.

nova-novncproxy </cli/nova-novncproxy>

Provides a VNC proxy for browsers, allowing VNC consoles to access virtual machines.

nova-spicehtml5proxy </cli/nova-spicehtml5proxy>

Provides a SPICE proxy for browsers, allowing SPICE consoles to access virtual machines.

nova-serialproxy </cli/nova-serialproxy>

Provides a serial console proxy, allowing users to access a virtual machine's serial console.

The architecture is covered in much greater detail in /admin/architecture.

architecture

Note

Some services have drivers that change how the service implements its core functionality. For example, the nova-compute service supports drivers that let you choose which hypervisor type it can use.

Deployment Considerations

There is information you might want to consider before doing your deployment, especially if it is going to be a larger deployment. For smaller deployments the defaults from the install guide </install/index> will be sufficient.

• Compute Driver Features Supported: While the majority of nova deployments use libvirt/kvm, you can use nova with other compute drivers. Nova attempts to provide a unified feature set across these, however, not all features are implemented on all backends, and not all features are equally well tested.
  • Feature Support by Use Case </user/feature-classification>: A view of what features each driver supports based on what's important to some large use cases (General Purpose Cloud, NFV Cloud, HPC Cloud).
  • Feature Support full list </user/support-matrix>: A detailed dive through features in each compute driver backend.
• Cells v2 configuration </admin/cells>: For large deployments, cells v2 cells allow sharding of your compute environment. Upfront planning is key to a successful cells v2 layout.
• Availability Zones </admin/availability-zones>: Availability Zones are an end-user visible logical abstraction for partitioning a cloud without knowing the physical infrastructure.
• Placement service <>: Overview of the placement service, including how it fits in with the rest of nova.
• Running nova-api on wsgi </user/wsgi>: Considerations for using a real WSGI container instead of the baked-in eventlet web server.

cells aggregates default-ports availability-zones configuration/index

Basic configuration

Once you have an OpenStack deployment up and running, you will want to manage it. The below guides cover everything from creating initial flavor and image to log management and live migration of instances.

• Quotas </admin/quotas>: Managing project quotas in nova.
• Scheduling </admin/scheduling>: How the scheduler is configured, and how that will impact where compute instances land in your environment. If you are seeing unexpected distribution of compute instances in your hosts, you'll want to dive into this configuration.
• Exposing custom metadata to compute instances </admin/vendordata>: How and when you might want to extend the basic metadata exposed to compute instances (either via metadata server or config drive) for your specific purposes.

manage-the-cloud services service-groups manage-logs root-wrap-reference ssh-configuration configuring-migrations live-migration-usage secure-live-migration-with-qemu-native-tls manage-volumes flavors admin-password-injection remote-console-access scheduling config-drive image-caching metadata-service quotas networking security-groups security vendordata notifications

Advanced configuration

OpenStack clouds run on platforms that differ greatly in the capabilities that they provide. By default, the Compute service seeks to abstract the underlying hardware that it runs on, rather than exposing specifics about the underlying host platforms. This abstraction manifests itself in many ways. For example, rather than exposing the types and topologies of CPUs running on hosts, the service exposes a number of generic CPUs (virtual CPUs, or vCPUs) and allows for overcommitting of these. In a similar manner, rather than exposing the individual types of network devices available on hosts, generic software-powered network ports are provided. These features are designed to allow high resource utilization and allows the service to provide a generic cost-effective and highly scalable cloud upon which to build applications.

This abstraction is beneficial for most workloads. However, there are some workloads where determinism and per-instance performance are important, if not vital. In these cases, instances can be expected to deliver near-native performance. The Compute service provides features to improve individual instance for these kind of workloads.

pci-passthrough cpu-topologies real-time huge-pages virtual-gpu file-backed-memory ports-with-resource-requests vdpa virtual-persistent-memory emulated-tpm uefi secure-boot sev managing-resource-providers compute-node-identification resource-limits cpu-models libvirt-misc

Maintenance

Once you are running nova, the following information is extremely useful.

• Upgrades <upgrades>: How nova is designed to be upgraded for minimal service impact, and the order you should do them in.

support-compute evacuate migration migrate-instance-with-snapshot upgrades node-down hw-machine-type hw-emulation-architecture soft-delete-shadow-tables