docs: Add Patrole RBAC field guide

This documentation update adds a README.rst to
patrole_tempest_plugin/tests/api which explains the RBAC field
guide. It is modeled after Tempest's API field guide [0][1]. The
README.rst is then referenced in a new field_guide section
under doc/source/field_guide.

[0] 28b252f7f6/tempest/api
[1] https://docs.openstack.org/tempest/latest/field_guide/api.html#api-field-guide

Change-Id: I877ce4a1f681bd483c7f71b02fd7bb2b4d3b3e2a

README.rst

@@ -9,9 +9,9 @@ Patrole - RBAC Integration Tempest Plugin
 =========================================
 
 Patrole is a security validation tool for verifying that Role-Based Access
-Control is correctly configured and enforced in a system. It runs Tempest-based
-API tests using specified RBAC roles, thus allowing deployments to verify that
-only intended roles have access to those APIs.
+Control is correctly configured and enforced in a system. It runs
+`Tempest`_-based API tests using specified RBAC roles, thus allowing
+deployments to verify that only intended roles have access to those APIs.
 
 Patrole currently offers testing for the following OpenStack services: Nova,
 Neutron, Glance, Cinder and Keystone.
@@ -20,6 +20,8 @@ Patrole is currently undergoing heavy development. As more projects move
 toward policy in code, Patrole will align its testing with the appropriate
 documentation.
 
+.. _Tempest: https://docs.openstack.org/tempest/latest/
+
 Design Principles
 -----------------
 

doc/source/field_guide/index.rst

@@ -1,8 +1,8 @@
-.. _patrole-testing:
+.. _patrole-field-guide:
 
-===============
-Patrole Testing
-===============
+============================
+Patrole Field Guide Overview
+============================
 
 Testing Scope
 =============
@@ -14,6 +14,15 @@ endpoints are correctly using ``oslo.policy`` for authorization.
 
 In other words, all tests in Patrole are RBAC tests.
 
+:ref:`rbac_field_guide`
+=======================
+
+RBAC tests are `Tempest`_-like API tests plus Patrole's
+:ref:`rbac-validation`. All Patrole tests are RBAC validation tests for the
+OpenStack API.
+
+.. _Tempest: https://docs.openstack.org/tempest/latest/
+
 Stable Tests
 ============
 

doc/source/field_guide/rbac.rst

@@ -0,0 +1,71 @@
+.. _rbac_field_guide:
+
+Patrole Field Guide to RBAC Tests
+=================================
+
+
+What are these tests?
+---------------------
+
+Patrole's primary responsibility is to ensure that your OpenStack cloud
+has properly configured Role-Based Access Control (RBAC). All Patrole
+tests cases are devoted to this responsibility. Tempest API clients
+and utility functions are leveraged to accomplish this goal, but such
+functionality is secondary to RBAC validation.
+
+Like Tempest, Patrole not only tests expected positive paths for RBAC
+validation, but also -- and more importantly -- negative paths. While
+Patrole could be thought of as validating RBAC, it more importantly
+verifies that your OpenStack cloud is secure from the perspective of
+RBAC (there are many gotchas when it comes to security, not just RBAC).
+
+Negative paths are arguably more important than positive paths when it
+comes to RBAC and by extension security, because it is essential that
+your cloud be secure from unauthorized access. For example, while it is
+important to verify that the admin role has access to admin-level
+functionality, it is of critical importance to verify that non-admin roles
+*do not* have access to such functionality.
+
+Unlike Tempest, Patrole accomplishes negative testing implicitly -- by
+abstracting it away in the background. Patrole dynamically determines
+whether a role should have access to an API depending on your cloud's
+policy configuration and then confirms whether that is true or false.
+
+
+Why are these tests in Patrole?
+-------------------------------
+
+These tests constitute the core mission in Patrole: to verify RBAC. These
+tests are mainly intended to validate RBAC, but can also *unofficially*
+be used to discover the policy-to-API mapping for an OpenStack component.
+
+It could be argued that some of these tests could be implemented in
+the projects themselves, but that approach has the following shortcomings:
+
+* The projects do not validate RBAC from an integration testing perspective.
+* By extension, RBAC across cross-service communication is not usually
+  validated.
+* The projects' tests do not pass all the metadata to ``oslo.policy`` that is
+  in reality passed by the deployed server to that library to determine
+  whether a given user is authorized to perform an API action.
+* The projects do not exhaustively do RBAC testing for all positive and
+  negative paths.
+* Patrole is designed to work with any role via configuration settings, but
+  on the other hand the projects handpick which roles to test.
+
+
+Scope of these tests
+--------------------
+
+RBAC tests should always use the Tempest implementation of the
+OpenStack API, to take advantage of Tempest's stable library.
+
+Each test should test a specific API endpoint and the related policy.
+
+Each policy should be tested in isolation of one another -- or at least
+as close to this rule as possible -- to ensure proper validation of RBAC.
+
+Each test should be able to work for positive and negative paths.
+
+All tests should be able to be run on their own, not depending on the
+state created by a previous test.

doc/source/index.rst

@@ -11,12 +11,27 @@ Patrole Configuration Guide
 .. toctree::
    :maxdepth: 2
 
-   installation
    configuration
    usage
-   testing
    sampleconf
 
+Patrole Installation Guide
+--------------------------
+
+.. toctree::
+   :maxdepth: 2
+
+   installation
+
+Field Guides
+============
+
+.. toctree::
+   :maxdepth: 1
+
+   field_guide/index
+   field_guide/rbac
+
 Developer's Guide
 =================