[openstack-dev] [nova][api] Strict validation in query parameters

Matt Riedemann mriedemos at gmail.com
Fri Jun 16 02:01:17 UTC 2017

On 6/15/2017 8:43 PM, Alex Xu wrote:
> We added new decorator 'query_schema' to support validate the query 
> parameters by JSON-Schema.
> It provides more strict valiadation as below:
> * set the 'additionalProperties=False' in the schema, it means that 
> reject any invalid query parameters and return HTTPBadRequest 400 to the 
> user.
> * use the marco function 'single_param' to declare the specific query 
> parameter only support single value. For example, the 'marker' 
> parameters for the pagination actually only one value is the valid. If 
> the user specific multiple values "marker=1&marker=2", the validation 
> will return 400 to the user.
> Currently there is patch related to this:
> https://review.openstack.org/#/c/459483/13/nova/api/openstack/compute/schemas/server_migrations.py
> So my question is:
> Are we all good with this strict validation in all the future microversion?
> I didn't remember we explicit agreement this at somewhere, just want to 
> double check this is the direction everybody want to go.
> Thanks
> Alex
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I think this is fine and makes sense for new microversions. The spec for 
consistent query parameter validation does talk about it a bit:


"The behaviour additionalProperties as below:

* When the value of additionalProperties is True means the extra query 
parameters are allowed. But those extra query parameters will be 
stripped out.
* When the value of additionalProperties is False means the extra query 
aren’t allowed.

The value of additionalProperties will be True until we decide to 
restrict the parameters in the future, and it will be changed with new 

I don't see a point in allowing someone to specify a query parameter 
multiple times if we only pick the first one from the list and use that.

There are certain query parameters that we allow multiple instances of, 
for sorting I believe. But for other things like filtering restricting 
to 1 should be fine, and using additionalProperties=False should also be 
fine on new microversions. For example, if we allow additional 
properties, someone could type the parameter name incorrectly and we'd 
just ignore it. With strict validation, we'll return a 400 which should 
be clear to the end user that what they requested as invalid and they 
need to fix it on their end.




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