How to enable ports pool with devstack¶

To enable the utilization of the ports pool feature through devstack, the next options needs to be set at the local.conf file:

First, you need to enable the pools by setting:
```
KURYR_USE_PORT_POOLS=True
```
Then, the proper pool driver needs to be set. This means that for the baremetal case you need to ensure the pod vif driver and the vif pool driver are set to the right baremetal drivers, for instance:
```
KURYR_POD_VIF_DRIVER=neutron-vif
KURYR_VIF_POOL_DRIVER=neutron
```
And if the use case is the nested one, then they should be set to:
```
KURYR_POD_VIF_DRIVER=nested-vlan
KURYR_VIF_POOL_DRIVER=nested
```
Then, in case you want to set a limit to the maximum number of ports, or increase/reduce the default one for the minimum number, as well as to modify the way the pools are repopulated, both in time as well as regarding bulk operation sizes, the next option can be included and modified accordingly:
```
KURYR_PORT_POOL_MIN=5
KURYR_PORT_POOL_MAX=0
KURYR_PORT_POOL_BATCH=10
KURYR_PORT_POOL_UPDATE_FREQ=20
```

How to enable ports pool with devstack