[cinder] Implementing a read-only administrator with the default reader role and system scope

Brian Rosmaita rosmaita.fossdev at gmail.com
Wed Sep 25 15:17:48 UTC 2019


On 9/23/19 5:48 PM, Miguel Lavalle wrote:
> Dear Cinder,
> 
> At my employer, Verizon Media, we want to implement a read only
> administrator like role using the Keystone default reader role scoped at
> system level. In the case of Nova, we've been following with interest
> their efforts
> here: https://review.opendev.org/#/q/topic:bp/policy-defaults-refresh+(status:open+OR+status:merged).
> I decided to test the same approach with Cinder. The good news is that
> the policy.py modules are almost the same in Nova and Cinder. I then
> looked, though, at some API calls,
> like https://docs.openstack.org/api-ref/block-storage/v3/index.html#volumes-volumes.
> The url in these calls include project_id, which in the case of a system
> scoped token I don't have. My questions are:
> 
> 1) Am I missing something?

No, I don't think so.

> 2) Are there any plans to implement a revision to these APIs in the near
> future so we can leverage the system scope and roles like reader for
> policy management?

No plans at the current time, though the PTG hasn't happened yet.

There are some checks deep down in Cinder independent of the policy
file; before we make changes, there will need to be a lot of tests
implemented so that we don't get regressions.

> 3) One short term alternative in my case is to add "wrappers" to those
> API calls where we want to enable the reader role with system scope,
> extract the project_id from the context and forward the call to the
> regular API. Does this make sense? Are there any caveats to this?

Instead you might want to configure the Cinder policy file so that it
behaves the way you want.  You can use this document as a starting point:

https://docs.openstack.org/cinder/latest/configuration/block-storage/policy-config-HOWTO.html

> 
> Best regards
> 
> Miguel




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