Sean had a really good point when he mentioned that the Developers know
what need to be enforced, and I think this is why he suggested that the
base policy implementation be in Python code, not the policy JSON DSL.
The main thrust of the dynamic policy has been to get the role-to-api
assignment more flexible. However, there is another side to each policy
rule; figureing out where the project (nee' tenant) id is in the
request; is it part of the URL, part of the request body, or in the
object returned from the database. This part really should be handled
by the developer working on the policy rule, and it should not be changed.
So...what if we say that we split policy into two checks; a role check,
and a scope check. Both checks must pass in order for the user to get
access to the API. The Scope check is not going to be dynamic; once
set, they will pretty much stay set. It might be done using the
policy.json, or done in code, but it will be separate from the role check.
The Neutron policy checks for things like
|"shared": "field:networks:shared=True", "shared_firewalls":
"field:firewalls:shared=True", "shared_firewall_policies":
"field:firewall_policies:shared=True", "shared_subnetpools":
"field:subnetpools:shared=True",
Would be handled by the dev teams later policy check; anything that
requires actually fetching the object from the database is postponed to
this stage.
|
The role check will come from the policy.json file. This will allow the
operator to fine tune how roles are handled. Any thing else that can be
explicitly checked based on the token will be fair game, but not API
specific values; no database fetch will be performed at this point.
The assumption is that this policy check could be generic enough to be
performed in middleware, and might even be enforced based on the URL
instead of the pseudo random namespacing we do now.
Does this suggestion work for Nova? I think it will make the overall
policy much easier to maintain in the field.
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