Glance’s public API calls may be restricted to certain sets of users using a policy configuration file. This document explains exactly how policies are configured and what they apply to.
A policy is composed of a set of rules that are used by the policy “Brain” in determining if a particular action may be performed by the authorized tenant.
A policy configuration file is a simply JSON object that contain sets of rules. Each top-level key is the name of a rule. Each rule is a string that describes an action that may be performed in the Glance API.
The actions that may have a rule enforced on them are:
get_images
- List available image entities
GET /v1/images
GET /v1/images/detail
GET /v2/images
get_image
- Retrieve a specific image entity
HEAD /v1/images/<IMAGE_ID>
GET /v1/images/<IMAGE_ID>
GET /v2/images/<IMAGE_ID>
download_image
- Download binary image data
GET /v1/images/<IMAGE_ID>
GET /v2/images/<IMAGE_ID>/file
upload_image
- Upload binary image data
POST /v1/images
PUT /v1/images/<IMAGE_ID>
PUT /v2/images/<IMAGE_ID>/file
copy_from
- Copy binary image data from URL
POST /v1/images
PUT /v1/images/<IMAGE_ID>
add_image
- Create an image entity
POST /v1/images
POST /v2/images
modify_image
- Update an image entity
PUT /v1/images/<IMAGE_ID>
PUT /v2/images/<IMAGE_ID>
publicize_image
- Create or update public images
POST /v1/images
with attribute is_public
= true
PUT /v1/images/<IMAGE_ID>
with attribute is_public
= true
POST /v2/images
with attribute visibility
= public
PUT /v2/images/<IMAGE_ID>
with attribute visibility
= public
communitize_image
- Create or update community images
POST /v2/images
with attribute visibility
= community
PUT /v2/images/<IMAGE_ID>
with attribute visibility
= community
delete_image
- Delete an image entity and associated binary data
DELETE /v1/images/<IMAGE_ID>
DELETE /v2/images/<IMAGE_ID>
add_member
- Add a membership to the member repo of an image
POST /v2/images/<IMAGE_ID>/members
get_members
- List the members of an image
GET /v1/images/<IMAGE_ID>/members
GET /v2/images/<IMAGE_ID>/members
delete_member
- Delete a membership of an image
DELETE /v1/images/<IMAGE_ID>/members/<MEMBER_ID>
DELETE /v2/images/<IMAGE_ID>/members/<MEMBER_ID>
modify_member
- Create or update the membership of an image
PUT /v1/images/<IMAGE_ID>/members/<MEMBER_ID>
PUT /v1/images/<IMAGE_ID>/members
POST /v2/images/<IMAGE_ID>/members
PUT /v2/images/<IMAGE_ID>/members/<MEMBER_ID>
manage_image_cache
- Allowed to use the image cache management API
To limit an action to a particular role or roles, you list the roles like so
{
"delete_image": ["role:admin", "role:superuser"]
}
The above would add a rule that only allowed users that had roles of either “admin” or “superuser” to delete an image.
Role checks are going to continue to work exactly as they already do. If the
role defined in the check is one that the user holds, then that will pass,
e.g., role:admin
.
To write a generic rule, you need to know that there are three values provided
by Glance that can be used in a rule on the left side of the colon (:
).
Those values are the current user’s credentials in the form of:
role
tenant
owner
The left side of the colon can also contain any value that Python can understand, e.g.,:
True
False
"a string"
&c.
Using tenant
and owner
will only work with images. Consider the
following rule:
tenant:%(owner)s
This will use the tenant
value of the currently authenticated user. It
will also use owner
from the image it is acting upon. If those two
values are equivalent the check will pass. All attributes on an image (as well
as extra image properties) are available for use on the right side of the
colon. The most useful are the following:
owner
protected
is_public
Therefore, you could construct a set of rules like the following:
{
"not_protected": "False:%(protected)s",
"is_owner": "tenant:%(owner)s",
"is_owner_or_admin": "rule:is_owner or role:admin",
"not_protected_and_is_owner": "rule:not_protected and rule:is_owner",
"get_image": "rule:is_owner_or_admin",
"delete_image": "rule:not_protected_and_is_owner",
"add_member": "rule:not_protected_and_is_owner"
}
Example 1. (The default policy configuration)
{
"default": ""
}
Note that an empty JSON list means that all methods of the Glance API are callable by anyone.
Example 2. Disallow modification calls to non-admins
{
"default": "",
"add_image": "role:admin",
"modify_image": "role:admin",
"delete_image": "role:admin"
}
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