support multiple nics

[poblin-orange]

CPI should be able to support multiple nics for specific use cases (routing, nat, etc ...)
This implies feeding the registry with NIC related information, so that bosh-agent can correlate and identify the distinct NIC for ip configuration.
Moreover, we will need direct cloudstack api access (jclouds 1.9.1 wont let us have direct NIC provisionning verbs)

[poblin-orange]

this feature as been added in openstack cpi last year. Its available in vcloud cpi.
Main impacts:

uncompatible with dhcp bootstraping

current cpi and stemcell rely on bootstrap dhcp and cloudstack metadata rest api to retrieve bosh-agent bootstrapping info. With multiple nic, we must set up new mechanisms to inject bosh-agent startup, analog to openstack and vcloud cpi

cdrom (vcloud / openstack)

The cpi must generate a cdrom image, with the required info. Upload it to cloudstack, and mount it on the vm.

disk (openstack)

The cpi must generate a disk image, upload it as a cloudstack volume, and mount it on the vm.

no multiplic nic support available in jclouds

The create_vm operation must be redevelopped using low level cloudstack REST Api. More over the registry feeding must record the generated ip, NIC mac address, so that bosh-agent can configure the NICs per network in an unambiguous fashion.

This feature requires a significant development effort, and cloudstack stemcell modifications.
Should focus on the project use cases to see if this effort is valuable.

NB: for some use cases, the recently added vip support could fit the bill ?

cc @gberche-orange