There are two types of image properties in Glance:

• Core Properties, as specified by the image schema.
• Meta Properties, which are arbitrary key/value pairs that can be
  added to an image.

Access to meta properties through Glance’s public API calls may be
restricted to certain sets of users, using a property protections
configuration file. Glance also reserves the os_glance
namespace of meta properties for its own use, and will refuse to let an
API user set any property prefixed as such.

This document explains exactly how property protections are
configured and what they apply to.

Constructing
a Property Protections Configuration File

A property protections configuration file follows the format of the
Glance API configuration file, which consists of sections, led by a
[section] header and followed by name = value
entries. Each section header is a regular expression matching a set of
properties to be protected.

Each section describes four key-value pairs, where the key is one of
create/read/update/delete, and the value is a comma
separated list of user roles that are permitted to perform that
operation in the Glance API. If any of the keys are not
specified, then the glance api service will not start
successfully.

In the list of user roles, @ means all roles and
! means no role. If both @ and ! are specified for
the same rule then the glance api service will not start

The path to the file should be specified in the
[DEFAULT] section of glance-api.conf as
follows.

property_protection_file=/path/to/file

If this config value is not specified, property protections are not
enforced. If the path is invalid, glance api service will not
start successfully.

The file may use either roles or policies to describe the property
protections. The config value should be specified in the
[DEFAULT] section of glance-api.conf as
follows.

property_protection_rule_format=<roles|policies>

The default value for property_protection_rule_format is
roles.

Property protections are applied in the order specified in the
configuration file. This means that if for example you specify a section
with [.*] at the top of the file, all proceeding sections
will be ignored.

If a property does not match any of the given rules, all operations
will be disabled for all roles.

If an operation is misspelled or omitted, that operation will be
disabled for all roles.

Disallowing read operations will also disallow
update/delete operations.

A successful HTTP request will return status 200 OK. If
the user is not permitted to perform the requested action,
403 Forbidden will be returned.