[nova][tripleo][rpm-packaging][kolla][puppet][debian][osa] Nova enforces that no DB credentials are allowed for the nova-compute service

Bal√°zs Gibizer balazs.gibizer at est.tech
Mon Nov 23 10:31:05 UTC 2020



On Sat, Nov 21, 2020 at 02:47, Thomas Goirand <zigo at debian.org> wrote:
> On 11/18/20 8:24 PM, Dan Smith wrote:
>>  which things are
>>  _not_allowed_ to be set for a service (such as db credentials on the
>>  compute).
> 
> I still don't understand why this is forbidden.
> 
> Sure, I understand what people wrote: that it is a security problem.
> 
> Can't nova-compute just *ignore* the db credentials, and then everyone
> is done with it, and moves on? That's a much more easy way to handle
> this problem, IMO.

It is still a security problem if nova-compute ignores the config as 
the config still exists on the hypervisor node (in some deployment 
scenarios)

There are two existing technical reasons too:
* Nova uses the [api_database]connection config to determine if the 
client of the compute RPC runs on the top level (i.e. super conductor) 
or locally in a cell (i.e. cell conductor or a nova-compute). [1]

* The fairly recent change[2] that prevents older that N-1 services to 
start also depends on the [api_database]connection config to determine 
the scope (global vs. cell local) of the query that gathers the current 
service level of the cluster.

I don't think that the [api_database]connection dependency can be 
removed from the super-conductor and cell-conductor differentiation 
perspective. From the nova-compute perspective we might be able to 
replace the [api_database]connection dependency with some hack. E.g to 
put the service name to the global CONF object at the start of the 
service binary and depend on that instead of other part of the config. 
But I feel pretty bad about this hack.

Cheers,
gibi

[1] 
https://github.com/openstack/nova/blob/e16800cc0aebf1174c5c0b6c4b043b09622524e9/nova/compute/rpcapi.py#L441
[2] 
https://github.com/openstack/nova/blob/e16800cc0aebf1174c5c0b6c4b043b09622524e9/nova/utils.py#L1064

> 
> Cheers,
> 
> Thomas Goirand (zigo)
> 





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