# Configuration Guide

The static configuration for nova lives in two main files: `nova.conf` and `policy.yaml`. These are described below. For a bigger picture view on configuring nova to solve specific problems, refer to the Nova Admin Guide.

## Configuration

Nova, like most OpenStack projects, uses INI-style configuration files to configure various services and utilities. This functionality is provided by the oslo.config project. oslo.config supports loading configuration from both individual configuration files and a directory of configuration files. By default, nova will search the below directories for two config files - `nova.conf` and `{prog}.conf`, where `prog` corresponds to the name of the service or utility being configured such as nova-compute - and two config directories - `nova.conf.d` and `{prog}.conf.d`:

- `${HOME}/.nova`

- `${HOME}`

- `/etc/nova`

- `/etc`

- `${SNAP_COMMON}/etc/nova/`

- `${SNAP}/etc/nova/`

Where a matching file is found, all other directories will be skipped. This behavior can be overridden by using the `--config-file` and `--config-dir` options provided for each executable.

More information on how you can use the configuration options to configure services and what configuration options are available can be found below.

- Configuration Guide: Detailed configuration guides for various parts of your Nova system. Helpful reference for setting up specific hypervisor backends.

- Config Reference: A complete reference of all configuration options available in the `nova.conf` file.

- Sample Config File: A sample config file with inline documentation.

## Policy

Nova, like most OpenStack projects, uses a policy language to restrict permissions on REST API actions. This functionality is provided by the oslo.policy project. oslo.policy supports loading policy configuration from both an individual configuration file, which defaults to `policy.yaml`, and one or more directories of configuration files, which defaults to `policy.d`. These must be located in the same directory as the `nova.conf` file(s). This behavior can be overridden by setting the `oslo_policy.policy_file` and `oslo_policy.policy_dirs` configuration options.

More information on how nova’s policy configuration works and about what policies are available can be found below.

- Policy Concepts: Starting in the Ussuri release, Nova API policy defines new default roles with system scope capabilities. These new changes improve the security level and manageability of Nova API as they are richer in terms of handling access at system and project level token with ‘Read’ and ‘Write’ roles.

- Policy Reference: A complete reference of all policy points in nova and what they impact.

- Sample Policy File: A sample nova policy file with inline documentation.

## Extra Specs

Nova uses flavor extra specs as a way to provide additional information to instances beyond basic information like amount of RAM or disk. This information can range from hints for the scheduler to hypervisor-specific configuration instructions for the instance.

- Extra Spec Reference: A complete reference for all extra specs currently recognized and supported by nova.

this page last updated: 2026-06-08 08:40:45

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