Port on creation is returned without the fixed_ips field populated

[Christian Rohmann]

I ran into an issue with port creation when using the openstack-terraform provider (which then uses Gophercloud) to access the Neutron API..... https://github.com/terraform-provider-openstack/terraform-provider-openstack/issues/1606

In short a port is created, but that port does not have the `fixed_ips` field populated.
This is the response to the create request:

```
{
  "ports": [
    {
      "admin_state_up": true,
      "allowed_address_pairs": [
        {
          "ip_address": "10.3.4.0/24",
          "mac_address": "fa:16:3e:3a:58:ec"
        }
      ],
      "binding:vnic_type": "normal",
      "created_at": "2023-08-23T10:06:12Z",
      "description": "",
      "device_id": "",
      "device_owner": "",
      "dns_assignment": [],
      "dns_name": "",
      "extra_dhcp_opts": [],
      "fixed_ips": [],
      "id": "9b37978b-ed53-41c2-983f-31570eb88259",
      "mac_address": "fa:16:3e:3a:58:ec",
      "name": "vpn",
      "network_id": "f946cedc-94d1-4bde-a680-f59d615ad2e3",
      "port_security_enabled": true,
      "project_id": "REDACTED",
      "revision_number": 1,
      "security_groups": [
        "87acb073-5123-4473-b33b-fc78f522c6b8"
      ],
      "status": "DOWN",
      "tags": [],
      "tenant_id": "REDACTED",
      "updated_at": "2023-08-23T10:06:12Z"
    }
  ]
}
```

If you look at my attempt to dive into the mechanics at https://github.com/terraform-provider-openstack/terraform-provider-openstack/issues/1606#issuecomment-1692082094, I am wondering if the IPAllocation might happening asynchronously and thus the response to the API call might not contain the fixed_ips if that takes to long?

All in all I just kindly as for a qualified comment if this is expected behavior (needs handing within the terraform provider) or a bug (can be fixed on the Neutron side).

[Brian Haley (brian-haley)]

IP allocation might be deferred in a routed network configuration where it is unknown where the port is going to "live" since we don't want to assign an IP that will not work on a particular compute node.

This state is normally shown in the POST response, but I believe you have to have the ip_allocation extension loaded.

This document has more information:

https://docs.openstack.org/neutron/latest/admin/config-routed-networks.html

That is the most likely reason fixed_ips is empty.

You can check in /etc/neutron/plugins/ml2/ml2_conf.ini to see what extension_drivers is set to, if you add this extension and restart neutron-server the API call should have that field (and value).

That's where I would start.

[Miro Tomaska (mtomaska)]

setting to incomplete for now until we determine if the ip_allocation is loaded as suggested in commnent#1

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

Hello:

This result is something expected if the network where the port is created has no subnets. For example [1]. Please check that case.

Regards.

[1]https://paste.opendev.org/show/bqIfpTY1NfhOmrwxcQiF/

[Launchpad Janitor (janitor)]

[Expired for neutron because there has been no activity for 60 days.]