Instead of a default policy.json file, policy defaults are now defined
in code. An operator need not supply policy.json data except to the
extent they want to override the defaults. Currently an empty
policy.json is still shipped because it is expected by devstack, but
this can be removed later. A sample policy.yaml file can be generated
using the genpolicy tox environment.
This partly fulfils the requirements of the policy in code goal[1].
However, because policies don't map 1:1 with APIs, it will not be
possible to fully document the policies until changes are made in how
policies are applied as proposed in https://review.opendev.org/528021
Due to the fact that existing policy files may rely on a rule named
"default" to specifiy policies not explicitly listed in the policy.json
file, all policies that are not admin-only by default now default to
"rule:default", so that the "default" rule will continue to apply to
those policies that are not listed in policy.json.
To ensure that this yields the expected policy in a standard
policy-in-code config file, the default value of the "default" rule is
now the empty string "". This is a change; between the Queens release
and now the default was set to "role:admin" to match the value specified
in the default policy.json file. An installation relying on both the
"default" rule for some policies and the default value of the default
rule may end up with a more permissive policy after upgrading. It's
likely that no such policies exist in the wild, because prior to the
Queens release the default value for the "default" rule was "@" (allow
all requests), so anybody relying on this rule will surely have
specified it explicitly in their policy.json.
Policies whose default is "role:admin" no longer use the "default" rule.
Therefore existing policy.json files that rely on the "default" rule for
those policies, and who have specified a value for the "default" rule
that is more permissive, will result in a more restrictive policy after
upgrading. It is unlikely that any of these policies exist in the wild
either.
[1] https://governance.openstack.org/tc/goals/selected/queens/policy-in-code.html
Change-Id: I8d1ccf5844078cc0b1652fb1130794daf07cedbc
5c17e4c7ef