Create floating IP from non-default pool without picking the actual IP address

[askfongjojo]

The explicit option for creating floating IP now accepts only one of the following:

• a specifc pool and IP address in that pool, or
• a specific IP address from the silo's default pool

But the option to auto-assign an address from a non-default pool no longer works, e.g.,

$ oxide api /v1/floating-ips?project=myproj -X POST --input - <<EOF
{
  "name": "specific-pool",
  "description": "a floating IP from a non-default pool",
  "address_allocator": {
    "type": "explicit",
    "pool": "alternate-pool"
  }
}
EOF
error; status code: 400 Bad Request
{
  "message": "unable to parse JSON body: address_allocator: missing field `ip` at line 8 column 1",
  "request_id": "3a6dcd4b-8734-45e2-9ada-9676da79e39a"
}
error

This used to work and seems like a regression.

[askfongjojo]

I should also mention that the other option, auto, ignores the pool n/v pair and only assigns from the silo's default IP pool. (Ideally, it should return an error about pool not being an appropriate parameter for that option.)

[bnaecker]

I don't think any of the internals here have changed for a while, so this might be due to the recent API changes. @zeeshanlakhani would you mind taking a look at this?