=============
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, which we refer to as scope.

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 scope (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. Additionally, other
service developers can use this document as a guide for implementing similar
patterns in their services.

Default roles and behaviors across scopes allow operators to delegate more
functionality to their team, auditors, customers, and users without maintaining
custom policies.

In addition to ``admin``, ``member``, and ``reader`` role, from 2023.2 (Bobcat)
release keystone will provide ``service`` role by default as well. Operators
can use this role for service to service API calls instead of using ``admin``
role for the same. The service role will be separate from ``admin``,
``member``, ``reader`` and will not implicate any  of these roles.

.. _`token guide`: https://docs.openstack.org/keystone/latest/admin/tokens-overview.html#authorization-scopes

-----------------
Roles Definitions
-----------------

The default roles provided by keystone via ``keystone-manage bootstrap``
(except for the ``service`` role) are related through role implications. The
``admin`` role implies the ``member`` role, and the ``member`` role implies
the ``reader`` role. These implications mean 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:

.. code-block:: yaml

    "identity:list_foo": "role:reader"

Instead of:

.. code-block:: yaml

    "identity:list_foo": "role:admin or role:member or role:reader"

Reader
======

.. warning::

   While it's possible to use the ``reader`` role to perform audits, we highly
   recommend assessing the viability of using ``reader`` for auditing from the
   perspective of the compliance target you're pursuing.

   The ``reader`` role is the least-privileged role within the role hierarchy
   described here. As such, OpenStack development teams, by default, do not
   advocate exposing sensitive information to users with the ``reader`` role,
   regardless of the scope. We have noted the need for a formal, read-only,
   role that is useful for inspecting all applicable resources within a
   particular scope, but it shouldn't be implemented as the lowest level of
   authorization. This work will come in a subsequent release where we support
   an elevated read-only role, that implies ``reader``, but also exposes
   sensitive information, where applicable.

   This will allow operators to grant third-party auditors a permissive role
   for viewing sensitive information, specifically for compliance targets that
   require it.

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.

It's imperative to note that ``reader`` is the least authoritative role in the
hierarchy because assignments using ``admin`` or ``member`` ultimately include
the ``reader`` role. We document this explicitly so that ``reader`` roles are not
overloaded with read-only access to sensitive information. For example, a deployment
pursuing a specific compliance target may want to leverage the ``reader`` role
to perform the audit. If the audit requires the auditor to evaluate sensitive
information, like license keys or administrative metadata, within a given
scope, auditors shouldn't expect to perform these operations with the
``reader`` role. We justify this design decision because sensitive information
should be explicitly protected, and not implicitly exposed.

The ``reader`` role should be implemented and used from the perspective of
least-privilege, which may or may not fulfill your auditing use case.

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).

Service
=======

We reserve the ``service`` role for Service-to-service communication. The aim
of a ``service`` role is to allow a service to communicate with another service
and possibly be granted elevated privileges by the service receiving the
request. Before the introduction of the ``service`` role, a service had to be
granted the ``admin`` role in order to have elevated privileges, which gave a
service powers way beyond what was necessary.  With the ``service`` role in
place, we can now allow all service-to-service APIs to default to the
``service`` role only. For example, a policy that requires
``service`` can be expressed as:

.. code-block:: yaml

    "identity:create_foo": "role:service"

There might be exception service-to-service APIs which project think are
useful to be used by admin or non-admin user then they can take the
exceptional decision to default them to user role and ``service`` role.  For
example, a policy that requires ``service`` and ``admin`` can be expressed as:

.. code-block:: yaml

    "identity:create_foo": "role:service" or "role:admin"

.. note::
    Unlike the other default roles, the ``service`` role is *not* a member
    of a role hierarchy.  It is a standalone role.

.. note::

   As of the Train release, keystone applies the following personas
   consistently across its API.

---------------
System Personas
---------------

This section describes authorization personas typically used for operators and
deployers. You can find all users with system role assignments using the
following query:

.. code-block:: console

    $ 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     |
    | reader |                        | system-support@Default |         |        | all    | False     |
    | admin  | operator@Default       |                        |         |        | all    | False     |
    | member | system-support@Default |                        |         |        | all    | False     |
    +--------+------------------------+------------------------+---------+--------+--------+-----------+

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:

.. code-block:: console

    $ openstack role assignment list --names --system all --role admin
    +-------+------------------+-----------------------+---------+--------+--------+-----------+
    | 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 list role assignments, users, projects, and
group memberships, among other resources.

The *system reader* persona is useful for members of a support team or auditors
if the audit doesn't require access to sensitive information. You can find
*system members* and *system readers* in your deployment with the following
assignments:

.. code-block:: console

    $ openstack role assignment list --names --system all --role member --role reader
    +--------+------------------------+------------------------+---------+--------+--------+-----------+
    | Role   | User                   | Group                  | Project | Domain | System | Inherited |
    +--------+------------------------+------------------------+---------+--------+--------+-----------+
    | reader |                        | system-support@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 <https://bugs.launchpad.net/keystone/+bug/1846817>`_.

---------------
Domain Personas
---------------

This section describes authorization personas for people who manage their own
domains, which contain projects, users, and groups. You can find all users with
role assignments on a specific domain using the following query:

.. code-block:: console

    $ openstack role assignment list --names --domain foobar
    +--------+-----------------+----------------------+---------+--------+--------+-----------+
    | Role   | User            | Group                | Project | Domain | System | Inherited |
    +--------+-----------------+----------------------+---------+--------+--------+-----------+
    | reader | support@Default |                      |         | foobar |        | False     |
    | admin  | jsmith@Default  |                      |         | foobar |        | False     |
    | admin  |                 | foobar-admins@foobar |         | foobar |        | False     |
    | member | jdoe@foobar     |                      |         | foobar |        | False     |
    +--------+-----------------+----------------------+---------+--------+--------+-----------+

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:

.. code-block:: console

    $ 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 support teams,
monitoring the details of an account, or auditing resources within a domain
assuming the audit doesn't validate sensitive information. You can find domain
members and domain readers with the following role assignments:

.. code-block:: console

    $ 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 | support@Default |       |         | foobar |        | False     |
    +--------+-----------------+-------+---------+--------+--------+-----------+

----------------
Project Personas
----------------

This section describes authorization personas for users operating within a
project. These personas are commonly used by end users. You can find all users
with role assignments on a specific project using the following query:

.. code-block:: console

    $ openstack role assignment list --names --project production
    +--------+----------------+----------------------------+-------------------+--------+--------+-----------+
    | Role   | User           | Group                      | Project           | Domain | System | Inherited |
    +--------+----------------+----------------------------+-------------------+--------+--------+-----------+
    | admin  | jsmith@Default |                            | production@foobar |        |        | False     |
    | admin  |                | production-admins@foobar   | production@foobar |        |        | False     |
    | member |                | foobar-operators@Default   | production@foobar |        |        | False     |
    | reader | alice@Default  |                            | production@foobar |        |        | False     |
    | reader |                | production-support@Default | production@foobar |        |        | False     |
    +--------+----------------+----------------------------+-------------------+--------+--------+-----------+

Project Administrators
======================

*Project administrators* can only view and modify data within the project they
have authorization on. 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:

.. code-block:: console

    $ 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:


.. code-block:: console

    $ 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 | alice@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`_.

.. _`documentation`: https://docs.openstack.org/oslo.policy/latest/admin/index.html
