Creating a pool with an existing name should thow an Exception

[Md Nadeem]

As of now creating a new pool with the name, of which a pool is already exist in the Env, will update the existing pool.

Prob: A user has to first check all existing pool name before choosing a name for the new pool, otherwise there is a probability that the user will update an existing pool unintentionally.

Solution: pool create api should through "PoolNameExist" exception in case of duplicate pool name.

Suggestion: Always use patch api to update an existing pool.

[Ryan Brown (sb-p)]

Is that something we shouldn't allow? I think users sending a flavor/pool with the same name would want that action to modify the existing one.

[Md Nadeem (mail2nadeem92)]

Ryan Brown: Thank you for your comment. As per my understanding

A user should use PATCH method to modify flavor/pool. If a user execute create command, most likely he wants to create a new pool/flavor.
A user can choose any random name for the pool/flavor, as there can be lots of pool and flavor already present in the Env, so there is a probability that a name clash will occur and user unintentionally modified the existing pool/flavor with out even realizing it what he has done, as create command return successful created response code<HTTP/1.1 201 Created>.

It is not a good idea that a user first check all the name of the pool/flavor and then decide to choose a unique name. So from my point of view, we should take care of it.

Ryan Brown: Please give your openion

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/238006