[2.0 beta 2] interface_set returns an interface without 'links' even if empty

[Andres Rodriguez]

eth0 returns empty links key,
eth1 has links key
lxcbr0 returns no links key, which is the issue

"interface_set": [
            {
                "parents": [],
                "type": "bridge",
                "enabled": true,
                "id": 7,
                "vlan": {
                    "primary_rack": null,
                    "fabric": "fabric-4",
                    "resource_uri": "/MAAS/api/2.0/vlans/5005/",
                    "secondary_rack": null,
                    "id": 5005,
                    "vid": 0,
                    "external_dhcp": "10.0.3.1",
                    "mtu": 1500,
                    "name": "untagged",
                    "dhcp_on": false
                },
                "tags": [],
                "params": "",
                "name": "lxcbr0",
                "mac_address": "26:e0:1b:f7:cc:63"
            },
            {
                "parents": [],
                "resource_uri": "/MAAS/api/2.0/nodes/4y3h7n/interfaces/4/",
                "discovered": null,
                "vlan": {
                    "primary_rack": null,
                    "fabric": "fabric-1",
                    "resource_uri": "/MAAS/api/2.0/vlans/5002/",
                    "secondary_rack": null,
                    "id": 5002,
                    "vid": 0,
                    "external_dhcp": null,
                    "mtu": 1500,
                    "name": "untagged",
                    "dhcp_on": false
                },
                "tags": [],
                "children": [],
                "type": "physical",
                "links": [
                    {
                        "id": 1,
                        "mode": "static",
                        "subnet": {
                            "resource_uri": "/MAAS/api/2.0/subnets/1/",
                            "space": "space-0",
                            "cidr": "10.245.136.0/21",
                            "name": "10.245.136.0/21",
                            "rdns_mode": 2,
                            "allow_proxy": true,
                            "id": 1,
                            "dns_servers": [],
                            "vlan": {
                                "primary_rack": null,
                                "fabric": "fabric-1",
                                "resource_uri": "/MAAS/api/2.0/vlans/5002/",
                                "secondary_rack": null,
                                "id": 5002,
                                "vid": 0,
                                "external_dhcp": null,
                                "mtu": 1500,
                                "name": "untagged",
                                "dhcp_on": false
                            },
                            "gateway_ip": "10.245.136.1"
                        },
                        "ip_address": "10.245.136.6"
                    }
                ],
                "name": "eth1",
                "enabled": true,
                "id": 4,
                "params": "",
                "effective_mtu": 1500,
                "mac_address": "de:ad:be:ef:6b:b3"
            },
            {
                "parents": [],
                "resource_uri": "/MAAS/api/2.0/nodes/4y3h7n/interfaces/1/",
                "discovered": null,
                "vlan": {
                    "primary_rack": null,
                    "fabric": "fabric-0",
                    "resource_uri": "/MAAS/api/2.0/vlans/5001/",
                    "secondary_rack": null,
                    "id": 5001,
                    "vid": 0,
                    "external_dhcp": null,
                    "mtu": 1500,
                    "name": "untagged",
                    "dhcp_on": false
                },
                "tags": [],
                "children": [],
                "type": "physical",
                "links": [],
                "name": "eth0",
                "enabled": false,
                "id": 1,
                "params": "",
                "effective_mtu": 1500,
                "mac_address": "52:54:00:12:34:56"
            }
        ],

[Mike Pontillo (mpontillo)]

I looked at the code and am not sure why this is happening.

in src/maasserver/api/interfaces.py we declare that 'links' is one of the displayed fields. Then we define a @classmethod called `links()` on the InterfaceHandler which calls `interface.get_links()` for the interface in question. This method (on the `Interface` class) always returns a list with zero or more elements. (*unless* an exception is raised) We do not override `get_links()` for any interface type.

Now, I would assume that you would see worse problems if an exception was thrown, such as not getting a result back at all. But I have to ask: are there any tracebacks in the log when this happens?