Migrate RBAC Policy Format from JSON to YAML

Oslo policy supports both JSON as well as YAML formatted policy file and config option for passing the policy_file defaults to policy.json.

JSON formatted file caused issues while deprecating policies with the combination of below things:

  • Packagers like to generate a sample policy for users to reference as they configure a service.

  • oslo.policy still defaults the filename of the policy file to policy.json for backward compatibility reasons. This encourages packages to generate a JSON sample policy file, which is not what we want.

  • Generating a sample policy file in JSON results in all the policy-in-code rules being overridden because it is not possible to comment out the default rules in JSON.

Because of the above, when a policy rule is deprecated in a service, users who have a JSON sample policy file will have the new rule applied immediately on upgrade. This does not give them a chance to deal with the change, as intended by the deprecation mechanism in oslo.policy (which would ordinarily apply an OR operation on the old rule and the new rule to ensure environments relying on the old rule will continue to work). This causes a lot of issues while doing the new policy changes of consistent and secure policy because we need to deprecate every policy rules.

After policy-in-code, the expectation was everyone will be relying on policy-in-code default unless they want to override any rule and if so then use YAML formatted file but that did not happen and from OpenStack side also we did not communicate it well to operators.

In Victoria cycle, we completed the below common part in oslo policy (oslo specs):

  1. Adding the warnings for JSON format file Oslo policy

  2. Providing the tool to convert the existing JSON

  3. Deprecate JSON output in policy CLI tools.

The operator can migrate their existing JSON file via oslo policy tool

As we are planning to make RBAC more secure and consistent, doing this in advance will help operators to move to YAML format and avoid any break when the operator re-generated the policy file in JSON format.

What projects need to do:

  1. Enable upgrade checks to detect the JSON format file which is defined in oslo.upgradecheck 1.2.0 and warn about it. Example

  2. Change the default for config policy_file via set_defaults. To avoid breaking the deployment, a fallback logic to use the existing policy.json is added in oslo.policy 3.6.0.

  3. Deprecate the JSON format support via warnings in doc and release notes.

Once all project finish this, we will be able to deprecate it in Oslo policy also which allow policy deprecation without causing pain to OpenStack deployers.

Release notes sample:

---
upgrade:
  - |
    The default value of ``[oslo_policy] policy_file`` config option has
    been changed from ``policy.json`` to ``policy.yaml``.
    Operators who are utilizing customized or previously generated
    static policy JSON files (which are not needed by default), should
    generate new policy files or convert them in YAML format. Use the
    `oslopolicy-convert-json-to-yaml
    <https://docs.openstack.org/oslo.policy/latest/cli/oslopolicy-convert-json-to-yaml.html>`_
    tool to convert a JSON to YAML formatted policy file in
    backward compatible way.
deprecations:
  - |
    Use of JSON policy files was deprecated by the ``oslo.policy`` library
    during the Victoria development cycle. As a result, this deprecation is
    being noted in the Wallaby cycle with an anticipated future removal of support
    by ``oslo.policy``. As such operators will need to convert to YAML policy
    files. Please see the upgrade notes for details on migration of any
    custom policy files.

Doc warning sample:

.. warning::

   JSON formatted policy file is deprecated since <project version>(Wallaby).
   This `oslopolicy-convert-json-to-yaml`__ tool will migrate your existing
   JSON-formatted policy file to YAML in a backward-compatible way.

.. __: https://docs.openstack.org/oslo.policy/latest/cli/oslopolicy-convert-json-to-yaml.html

Example:

Tracking for this work will be done in this etherpad

Champion

Ghanshyam Mann <gmann@ghanshyammann.com> (gmann)

Gerrit Topic

To facilitate tracking, commits related to this goal should use the gerrit topic:

policy-json-to-yaml

Completion Criteria

  1. Add upgrade checks to detect the JSON format file and warn about it.

  2. Change the default for config policy_file via set_defaults.

  3. Deprecate the JSON format support via warnings in doc and release notes.

Current State / Anticipated Impact

Olso side works to provide migration tool and two projects Nova and Cyborg completed it. Also, Cinder did one part of changing the default value.