13 KiB
Default Roles
Primer
Like most OpenStack services, keystone protects its API using role-based access control (RBAC).
Users can access different APIs depending on the roles they have on a project, domain, or system.
As of the Rocky release, keystone provides three roles called
admin
, member
, and reader
by
default. Operators can grant these roles to any actor (e.g., group or
user) on any target (e.g., system, domain, or project). If you need a
refresher on authorization scopes and token types, please refer to the
token
guide. The following sections describe how each default role behaves
with keystone's API across different scopes.
Default roles and behaviors across scopes allow operators to delegate more functionality to their team, auditors, customers, and users without maintaining custom policies.
Roles Definitions
The default roles imply one another. The admin
role
implies the member
role, and the member
role
implies the reader
role. This implication means users with
the admin
role automatically have the member
and reader
roles. Additionally, users with the
member
role automatically have the reader
role. Implying roles reduces role assignments and forms a natural
hierarchy between the default roles. It also reduces the complexity of
default policies by making check strings short. For example, a policy
that requires reader
can be expressed as:
"identity:list_foo": "role:reader"
Instead of:
"identity:list_foo": "role:admin or role:member or role:reader"
Reader
The reader
role provides read-only access to resources
within the system, a domain, or a project. Depending on the assignment
scope, two users with the reader
role can expect different
API behaviors. For example, a user with the reader
role on
the system can list all projects within the deployment. A user with the
reader
role on a domain can only list projects within their
domain.
By analyzing the scope of a role assignment, we increase the
re-usability of the reader
role and provide greater
functionality without introducing more roles. For example, to accomplish
this without analyzing assignment scope, you would need
system-reader
, domain-reader
, and
project-reader
roles in addition to custom policies for
each service.
Member
Within keystone, there isn't a distinct advantage to having the
member
role instead of the reader
role. The
member
role is more applicable to other services. The
member
role works nicely for introducing granularity
between admin
and reader
roles. Other services
might write default policies that require the member
role
to create resources, but the admin
role to delete them. For
example, users with reader
on a project could list
instance, users with member
on a project can list and
create instances, and users with admin
on a project can
list, create, and delete instances. Service developers can use the
member
role to provide more flexibility between
admin
and reader
on different scopes.
Admin
We reserve the admin
role for the most privileged
operations within a given scope. It is important to note that having
admin
on a project, domain, or the system carries separate
authorization and are not transitive. For example, users with
admin
on the system should be able to manage every aspect
of the deployment because they're operators. Users with
admin
on a project shouldn't be able to manage things
outside the project because it would violate the tenancy of their role
assignment (this doesn't apply consistently since services are
addressing this individually at their own pace).
Note
As of the Train release, keystone applies the following personas consistently across its API.
System Administrators
System administrators are allowed to manage every resource in keystone. System administrators are typically operators and cloud administrators. They can control resources that ultimately affect the behavior of the deployment. For example, they can add or remove services and endpoints in the catalog, create new domains, add federated mappings, and clean up stale resources, like a user's application credentials or trusts.
You can find system administrators in your deployment with the following assignments:
$ openstack role assignment list --names --system all
+-------+------------------+-----------------------+---------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+-------+------------------+-----------------------+---------+--------+--------+-----------+
| admin | | system-admins@Default | | | all | False |
| admin | admin@Default | | | | all | False |
| admin | operator@Default | | | | all | False |
+-------+------------------+-----------------------+---------+--------+--------+-----------+
System Members & System Readers
In keystone, system members and system readers are very similar and have the same authorization. Users with these roles on the system can view all resources within keystone. They can audit role assignments, users, projects, and group memberships, among other resources.
The system reader persona is useful for auditors or members of a support team. You can find system members and system readers in your deployment with the following assignments:
$ openstack role assignment list --names --system all --role member --role reader
+--------+------------------------+-------------------------+---------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+--------+------------------------+-------------------------+---------+--------+--------+-----------+
| reader | | system-auditors@Default | | | all | False |
| admin | operator@Default | | | | all | False |
| member | system-support@Default | | | | all | False |
+--------+------------------------+-------------------------+---------+--------+--------+-----------+
Warning
Filtering system role assignments is currently broken and is being tracked as a bug.
Domain Administrators
Domain administrators can manage most aspects of the domain or its contents. These users can create new projects and users within their domain. They can inspect the role assignments users have on projects within their domain.
Domain administrators aren't allowed to access system-specific resources or resources outside their domain. Users that need control over project, group, and user creation are a great fit for domain administrators.
You can find domain administrators in your deployment with the following role assignment:
$ openstack role assignment list --names --domain foobar --role admin
+-------+----------------+----------------------+---------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+-------+----------------+----------------------+---------+--------+--------+-----------+
| admin | jsmith@Default | | | foobar | | False |
| admin | | foobar-admins@foobar | | foobar | | False |
+-------+----------------+----------------------+---------+--------+--------+-----------+
Domain Members & Domain Readers
Domain members and domain readers have the same relationship as system members and system readers. They're allowed to view resources and information about their domain. They aren't allowed to access system-specific information or information about projects, groups, and users outside their domain.
The domain member and domain reader use-cases are great for auditing, support, or monitoring the details of an account. You can find domain members and domain readers with the following role assignments:
$ openstack role assignment list --names --role member --domain foobar
+--------+-------------+-------+---------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+--------+-------------+-------+---------+--------+--------+-----------+
| member | jdoe@foobar | | | foobar | | False |
+--------+-------------+-------+---------+--------+--------+-----------+
$ openstack role assignment list --names --role reader --domain foobar
+--------+-----------------+-------+---------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+--------+-----------------+-------+---------+--------+--------+-----------+
| reader | auditor@Default | | | foobar | | False |
+--------+-----------------+-------+---------+--------+--------+-----------+
Project Administrators
Project administrators can only view and modify data within the project in their role assignment. They're able to view information about their projects and set tags on their projects. They're not allowed to view system or domain resources, as that would violate the tenancy of their role assignment. Since the majority of the resources in keystone's API are system and domain-specific, project administrators don't have much authorization.
You can find project administrators in your deployment with the following role assignment:
$ openstack role assignment list --names --project production --role admin
+-------+----------------+--------------------------+-------------------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+-------+----------------+--------------------------+-------------------+--------+--------+-----------+
| admin | jsmith@Default | | production@foobar | | | False |
| admin | | production-admins@foobar | production@foobar | | | False |
+-------+----------------+--------------------------+-------------------+--------+--------+-----------+
Project Members & Project Readers
Project members and project readers can discover information about their projects. They can access important information like resource limits for their project, but they're not allowed to view information outside their project or view system-specific information.
You can find project members and project readers in your deployment with the following role assignments:
$ openstack role assignment list --names --project production --role member
+--------+------+--------------------------+-------------------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+--------+------+--------------------------+-------------------+--------+--------+-----------+
| member | | foobar-operators@Default | production@foobar | | | False |
+--------+------+--------------------------+-------------------+--------+--------+-----------+
$ openstack role assignment list --names --project production --role reader
+--------+-----------------+----------------------------+-------------------+--------+--------+-----------+
| Role | User | Group | Project | Domain | System | Inherited |
+--------+-----------------+----------------------------+-------------------+--------+--------+-----------+
| reader | auditor@Default | | production@foobar | | | False |
| reader | | production-support@Default | production@foobar | | | False |
+--------+-----------------+----------------------------+-------------------+--------+--------+-----------+
Writing Policies
If the granularity provided above doesn't meet your specific use-case, you can still override policies and maintain them manually. You can read more about how to do that in oslo.policy usage documentation.