cannot unlink subnet after commission

[Robert Varjasi]

I try to use the API call op-unlink_subnet but its not working for the primary (PXE) interface. An unexpected link ID also appears which I cannot read directly but its in the database:

```
HQ-A root@maas-hq-a:/home/ubuntu# maas admin interface unlink-subnet yyb3ck 556 id=1
{"id": ["'1' is not a valid id. It should be one of: '5691', '5692'."]}

HQ-A root@maas-hq-a:/home/ubuntu# maas admin interface read yyb3ck|grep 5691
HQ-A root@maas-hq-a:/home/ubuntu#

```

Here the ID 5691 is not valid.

```
maasdb=# select * from maasserver_staticipaddress where id=5691;
  id | created | updated | ip | alloc_type | subnet_id | user_id | lease_time | temp_expires_on
------+-------------------------------+-------------------------------+----+------------+-----------+---------+------------+-----------------
 5691 | 2023-09-15 18:07:59.054702+02 | 2023-09-15 18:16:52.066979+02 | | 6 | 1 | | 0 |
(1 row)

maasdb=# select * from maasserver_staticipaddress where id=5692;
  id | created | updated | ip | alloc_type | subnet_id | user_id | lease_time | temp_expires_on
------+-------------------------------+-------------------------------+----+------------+-----------+---------+------------+-----------------
 5692 | 2023-09-15 18:07:59.270894+02 | 2023-09-15 18:07:59.270894+02 | | 0 | 1 | | 0 |
(1 row)

```

I suppose this link is a remnant of a commission which is preventing me to unlink and then reconfigure the link properly with my own settings.

If I unlink this "hidden" link too then unlink_subnet functions starts behaving normally.

[Jacopo Rota (r00ta)]

Hi Robert,

Could you include in the bug report the version of MAAS that you are using as well as the installation type (deb/snap)?

Could you add the steps to reproduce your issue as well?

[Robert Varjasi (robert.varjasi)]

MAAS version is 3.2.9

[Robert Varjasi (robert.varjasi)]

maas-hq-a:~$ dpkg -l maas|tail -1
ii maas 1:3.2.9-12055-g.c3d5597a7-0ubuntu1~20.04.1 all

[Robert Varjasi (robert.varjasi)]

Its a DEB pkg.

[Robert Varjasi (robert.varjasi)]

Reproduce the issue:

1.) commission a node
2.) try to unlink the primary (PXE) interface which will fail

[Jacopo Rota (r00ta)]

From my understanding there is no bug here. The correct usage of that function should be

```
ID_LINK=$(maas admin interface read <your_machine_id> <your_interface_id> | jq ".links[].id")
maas admin interface unlink-subnet <your_machine_id> <your_interface_id> id=$ID_LINK
```

and then your interface should be unlinked. Could you confirm?

[Robert Varjasi (robert.varjasi)]

Hi,

Unfortunately I cannot confirm that. Unlink should work one-by-one if there are more than one links attached to an interface but it is not working for me. Your solution is to read all links and then unlink also not a solution either. Please again read my posts carefully. I said there is a hidden link, which is a remnant and cannot readable by any API call. This is definitely a BUG I think.

[Robert Varjasi (robert.varjasi)]

As you can see the ID 5699 is hidden:

HQ-A root@maas-hq-a:/home/ubuntu# maas admin interface unlink-subnet yyb3ck 556 id=1
{"id": ["'1' is not a valid id. It should be one of: '5699', '5700'."]}
HQ-A root@maas-hq-a:/home/ubuntu# maas admin interface read yyb3ck 556|jq '.links[].id'
5700

And If I try to unlink 5700 as a normal API client (Terraform for example) would do, Its failed:

HQ-A root@maas-hq-a:/home/ubuntu# maas admin interface unlink-subnet yyb3ck 556 id=5700
Success.
Machine-readable output follows:
{
    "tags": [],
    "firmware_version": null,
    "link_speed": 0,
    "sriov_max_vf": 0,
    "id": 556,
    "effective_mtu": 1500,
    "name": "ens4",
    "links": [
        {
            "id": 5705,
            "mode": "link_up",
            "subnet": {
                "name": "oam",
                "description": "",
                "vlan": {
                    "vid": 0,
                    "mtu": 1500,
                    "dhcp_on": true,
                    "external_dhcp": null,
                    "relay_vlan": null,
                    "fabric_id": 0,
                    "id": 5001,
                    "secondary_rack": null,
                    "name": "untagged",
                    "fabric": "fabric-0",
                    "primary_rack": "qxr7ms",
                    "space": "undefined",
                    "resource_uri": "/MAAS/api/2.0/vlans/5001/"
                },
                "cidr": "192.168.104.0/24",
                "rdns_mode": 2,
                "gateway_ip": "192.168.104.254",
                "dns_servers": [
                    "192.168.104.11",
                    "192.168.104.12",
                    "192.168.104.7"
                ],
                "allow_dns": true,
                "allow_proxy": true,
                "active_discovery": false,
                "managed": true,
                "disabled_boot_architectures": [],
                "id": 1,
                "space": "undefined",
                "resource_uri": "/MAAS/api/2.0/subnets/1/"
            }
        }
    ],
    "parents": [],
    "link_connected": true,
    "vendor": "Red Hat, Inc.",
    "type": "physical",
    "discovered": [
        {
            "subnet": {
                "name": "oam",
                "description": "",
                "vlan": {
                    "vid": 0,
                    "mtu": 1500,
                    "dhcp_on": true,
                    "external_dhcp": null,
                    "relay_vlan": null,
                    "fabric_id": 0,
                    "id": 5001,
                    "secondary_rack": null,
                    "name": "untagged",
                    "fabric": "fabric-0",
                    "primary_rack": "qxr7ms",
                    "space": "undefined",
                    "resource_uri": "/MAAS/api/2.0/vlans/5001/"
                },
                "cidr": "192.168.104.0/24",
                "rdns_mode": 2,
                "gateway_ip": "192.168.104.254",
                "dns_servers": [
                    "192.168.104.11",
                    "192.168.104.12",
                    "192.168.104.7"
                ],
                "allow_dns": true,
                "allo...

[Jacopo Rota (r00ta)]

The link you see is of type `link_up` and you can actually ignore it as your interface was properly detached from the subnet already.

[Robert Varjasi (robert.varjasi)]

Sorry but I cannot ignore this. The subnet is not properly detached. Only the IP Mode went from Auto to Unconfigured. The subnet is still attached to my interface.

[Robert Varjasi (robert.varjasi)]

Just to clarify I know how MAAS should work and we are using it for years. This problem is a blocker for us because we wants to change the primary link IP mode to STATIC with an API client (automation) and we cannot do that because this weird behavior.

[Jacopo Rota (r00ta)]

Right, I see. Thanks for reporting this!

[Robert Varjasi (robert.varjasi)]

Thank you!

[Joao Paulo (jonaspaulo)]

Hi,

I came across the same problem for exactly the same use case (automation).
What i did meanwhile (not ideally but for me it solves the question) is just change the vlan of the PXE interface (ens1f0 in my case) to another dummy vlan (which also sets the PXE interface to unconfigured) and eventually change it back to the provisioning vlan (or just let it be on the dummy one):

ens1f0_interface_id=$(sudo maas admin interfaces read $system_id -k | jq -r '.[] | select (.name=="ens1f0") | .id')
dummy_vlan_id=$(sudo maas admin vlans read 3 -k | jq -r '.[] | select (.name=="dummy") | .id')
provisioning_vlan_id=$(sudo maas admin vlans read 0 -k | jq -r '.[] | select (.name=="untagged") | .id')
sudo maas admin interface update $system_id $ens1f0_interface_id vlan=$dummy_vlan_id-k &>/dev/null
sudo maas admin interface update $system_id $ens1f0_interface_id vlan=$provisioning_vlan_id -k &>/dev/null (optionally change it back)

Hope it helps someone until the fix.
Thanks
BR