openstack client does not pass prefixlen when creating subnet

[James Denton]

Version: Pike
OpenStack Client: 3.12.0

When testing Subnet Pool functionality, I found that the behavior between the openstack and neutron clients is different.

Subnet pool:

root@controller01:~# openstack subnet pool show MySubnetPool
+-------------------+--------------------------------------+
| Field | Value |
+-------------------+--------------------------------------+
| address_scope_id | None |
| created_at | 2018-03-07T13:18:22Z |
| default_prefixlen | 8 |
| default_quota | None |
| description | |
| id | e49703d8-27f4-4a16-9bf4-91a6cf00fff3 |
| ip_version | 4 |
| is_default | False |
| max_prefixlen | 32 |
| min_prefixlen | 8 |
| name | MySubnetPool |
| prefixes | 172.31.0.0/16 |
| project_id | 9233b6b4f6a54386af63c0a7b8f043c2 |
| revision_number | 0 |
| shared | False |
| tags | |
| updated_at | 2018-03-07T13:18:22Z |
+-------------------+--------------------------------------+

When attempting to create a /28 subnet from that pool with the openstack client, the following error is observed:

root@controller01:~# openstack subnet create \
> --subnet-pool MySubnetPool \
> --prefix-length 28 \
> --network MyVLANNetwork2 \
> MyFlatSubnetFromPool
HttpException: Internal Server Error (HTTP 500) (Request-ID: req-61b3f00a-9764-4bcb-899d-e85d66f54e5a), Failed to allocate subnet: Insufficient prefix space to allocate subnet size /8.

However, the same request is successful with the neutron client:

root@controller01:~# neutron subnet-create --subnetpool MySubnetPool --prefixlen 28 --name MySubnetFromPool MyVLANNetwork2
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
Created a new subnet:
+-------------------+-----------------------------------------------+
| Field | Value |
+-------------------+-----------------------------------------------+
| allocation_pools | {"start": "172.31.0.2", "end": "172.31.0.14"} |
| cidr | 172.31.0.0/28 |
| created_at | 2018-03-07T13:35:35Z |
| description | |
| dns_nameservers | |
| enable_dhcp | True |
| gateway_ip | 172.31.0.1 |
| host_routes | |
| id | 43cb9dda-1b7e-436d-9dc1-5312866a1b63 |
| ip_version | 4 |
| ipv6_address_mode | |
| ipv6_ra_mode | |
| name | MySubnetFromPool |
| network_id | e01ca743-607c-4a94-9176-b572a46fba84 |
| project_id | 9233b6b4f6a54386af63c0a7b8f043c2 |
| revision_number | 0 |
| service_types | |
| subnetpool_id | e49703d8-27f4-4a16-9bf4-91a6cf00fff3 |
| tags | |
| tenant_id | 9233b6b4f6a54386af63c0a7b8f043c2 |
| updated_at | 2018-03-07T13:35:35Z |
+-------------------+-----------------------------------------------+

The payload is different between these clients - the openstack client fails to send the prefixlen key.

openstack client:

REQ: curl -g -i -X POST http://controller01:9696/v2.0/subnets -H "User-Agent: openstacksdk/0.9.17 keystoneauth1/3.1.0 python-requests/2.18.1 CPython/2.7.12" -H "Content-Type: application/json" -H "X-Auth-Token: {SHA1}ec04a71699eee2c70dc4abb35037de272523fef0" -d '{"subnet": {"network_id": "e01ca743-607c-4a94-9176-b572a46fba84", "ip_version": 4, "name": "MyFlatSubnetFromPool", "subnetpool_id": "e49703d8-27f4-4a16-9bf4-91a6cf00fff3"}}'
http://controller01:9696 "POST /v2.0/subnets HTTP/1.1" 500 160

neutron client:

REQ: curl -g -i -X POST http://controller01:9696/v2.0/subnets -H "User-Agent: python-neutronclient" -H "Content-Type: application/json" -H "Accept: application/json" -H "X-Auth-Token: {SHA1}b3b6f0fa14c2b28c5c9784f857ee753455c1d375" -d '{"subnet": {"network_id": "e01ca743-607c-4a94-9176-b572a46fba84", "prefixlen": "28", "ip_version": 4, "subnetpool_id": "e49703d8-27f4-4a16-9bf4-91a6cf00fff3", "name": "MySubnetFromPool"}}'

This appears to stem from prefixlen missing as a query parameter and property in the python-openstacksdk here:

https://github.com/openstack/python-openstacksdk/blob/master/openstack/network/v2/subnet.py#L32
https://github.com/openstack/python-openstacksdk/blob/master/openstack/network/v2/subnet.py#L43

The Neutron docs do not show prefixlen as a subnet as a valid property, which could be why:

https://developer.openstack.org/api-ref/network/v2/index.html#create-subnet

I was able to patch the openstack SDK in my environment and got the client to work. Please let me know if you have any questions!

[Brian Haley (brian-haley)]

So it looks like there are multiple issues here - the api-ref in neutron-lib is missing this field, and as you stated, the sdk is missing it probably because it's not listed. I'll ping someone to take a look at the api-ref. I'm not that familiar with the sdk but if you had a simple patch that helps feel free to post it and I'll take a look. Thanks.

[James Denton (james-denton)]

Hi Brian,

Thanks for taking a look. Here is the patch in question:

https://review.openstack.org/550558

James

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/550588

[Brian Haley (brian-haley)]

Just a comment since Amotoki commented in my neutron-lib api-ref change - when the subnetpool was created, the default_prefixlen value should have been specified (in this case at 28), that way callers don't need to specify it. I think it defaults to min_prefixlen if not specified. We still need to fix the bug...

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/550588
Committed: https://git.openstack.org/cgit/openstack/neutron-lib/commit/?id=ce10b9df28ece6daee1f199740b672aae707630b
Submitter: Zuul
Branch: master

commit ce10b9df28ece6daee1f199740b672aae707630b
Author: Brian Haley <email address hidden>
Date: Wed Mar 7 15:08:42 2018 -0500

    Add prefixlen to subnet api-ref for create actions

    Prefixlen is used in subnet creation when allocating a subnet
    from a subnet pool.

    Change-Id: I251944ca15434ed9b17deb829cca985cd94a0bd1
    Closes-bug: #1754062

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron-lib 1.14.0 release.

[Francois Deppierraz (francois-ctrlaltdel)]

I'm not sure this issue is actually fixed, I gave it a try today without any luck using the lastest python-openstackclient.

$ pip list | egrep "openstack|neutron"
openstacksdk (0.20.0)
python-neutronclient (6.11.0)
python-openstackclient (3.17.0)
python-openstacksdk (0.5.2)
$ openstack --version
openstack 3.17.0
$ openstack --debug subnet create --use-default-subnet-pool --prefix-length 24 --network test test
[...]
https://XXX:9696 "POST /v2.0/subnets HTTP/1.1" 201 593
RESP: [201] Connection: close Content-Length: 593 Content-Type: application/json; charset=UTF-8 Date: Mon, 17 Dec 2018 16:10:59 GMT X-Openstack-Request-Id: req-2744992c-5302-4f7a-9870-220e868d85a1
RESP BODY: {"subnet": {"description": "", "enable_dhcp": true, "network_id": "6b350cce-adf8-44fa-86b2-140670cc99b8", "tenant_id": "505f48f68ebc4d4f87cf64e56b40f3de", "created_at": "2018-12-17T16:10:59", "dns_nameservers": [], "updated_at": "2018-12-17T16:10:59", "gateway_ip": "X.X.X.X", "ipv6_ra_mode": null, "allocation_pools": [{"start": "X.X.X.X", "end": "X.X.X.X"}], "host_routes": [], "ip_version": 4, "ipv6_address_mode": null, "cidr": "X.X.X.X/26", "id": "6d75a4e9-31fd-4364-8352-050e3197dc56", "subnetpool_id": "d563bbd9-90c2-4ccb-af08-92339b05396c", "name": "test"}}
[...]
| cidr | X.X.X.X/26 |

[James Denton (james-denton)]

@Francois - This isn't completely fixed, yet, but a new patch set went up today.

[Michal Arbet (michalarbet)]

@James , could you please show me that patch ? Thanks

[James Denton (james-denton)]

@Michal

https://review.openstack.org/#/c/550558/

[Bernard Cafarelli (bcafarel)]

Marking as fix released in openstacksdk with https://review.opendev.org/#/c/550558/