Description of problem:

Version-Release number of selected component (if applicable):
build openshift/api#2005

How reproducible:
Always
Steps to Reproduce:

1. Create ns ns1 and create crd using below yaml

apiVersion: k8s.ovn.org/v1
kind: UserDefinedNetwork
metadata:
  name: udn-network
spec:
  topology: Layer3
  layer3:
    role: Primary
    subnets: 
    - cidr: 10.200.0.0/26
      hostsubnet: 29

2.

3.

Actual results:
Will get below error. It seems host subnet is hardcode to 24

% oc get userdefinednetwork -n ns1 -o yaml
apiVersion: v1
items:
- apiVersion: k8s.ovn.org/v1
  kind: UserDefinedNetwork
  metadata:
    creationTimestamp: "2024-08-26T04:20:36Z"
    finalizers:
    - k8s.ovn.org/user-defined-network-protection
    generation: 1
    name: udn-network
    namespace: ns1
    resourceVersion: "73554"
    uid: e0e4db8f-792e-441d-8f2d-89ba1eef3a27
  spec:
    layer3:
      role: Primary
      subnets:
      - cidr: 10.200.0.0/26
    topology: Layer3
  status:
    conditions:
    - lastTransitionTime: "2024-08-26T04:20:36Z"
      message: 'failed to generate NetworkAttachmentDefinition: failed to render CNI
        network config: cannot use a host subnet length mask shorter than or equal
        to the cluster subnet mask. host subnet length: 24, cluster subnet length:
        26'
      reason: SyncError
      status: "False"
      type: NetworkReady
kind: List
metadata:
  resourceVersion: ""

Expected results:
Custom hostsubnet length should take effect.

Additional info:

Please fill in the following template while reporting a bug and provide as much relevant information as possible. Doing so will give us the best chance to find a prompt resolution.

Affected Platforms:

Is it an

1. internal CI failure
2. customer issue / SD
3. internal RedHat testing failure

If it is an internal RedHat testing failure:

• Please share a kubeconfig or creds to a live cluster for the assignee to debug/troubleshoot along with reproducer steps (specially if it's a telco use case like ICNI, secondary bridges or BM+kubevirt).

If it is a CI failure:

• Did it happen in different CI lanes? If so please provide links to multiple failures with the same error instance
• Did it happen in both sdn and ovn jobs? If so please provide links to multiple failures with the same error instance
• Did it happen in other platforms (e.g. aws, azure, gcp, baremetal etc) ? If so please provide links to multiple failures with the same error instance
• When did the failure start happening? Please provide the UTC timestamp of the networking outage window from a sample failure run
• If it's a connectivity issue,
• What is the srcNode, srcIP and srcNamespace and srcPodName?
• What is the dstNode, dstIP and dstNamespace and dstPodName?
• What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)

If it is a customer / SD issue:

• Provide enough information in the bug description that Engineering doesn’t need to read the entire case history.
• Don’t presume that Engineering has access to Salesforce.
• Do presume that Engineering will access attachments through supportshell.
• Describe what each relevant attachment is intended to demonstrate (failed pods, log errors, OVS issues, etc).
• Referring to the attached must-gather, sosreport or other attachment, please provide the following details:
  • If the issue is in a customer namespace then provide a namespace inspect.
  • If it is a connectivity issue:
    • What is the srcNode, srcNamespace, srcPodName and srcPodIP?
    • What is the dstNode, dstNamespace, dstPodName and dstPodIP?
    • What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)
    • Please provide the UTC timestamp networking outage window from must-gather
    • Please provide tcpdump pcaps taken during the outage filtered based on the above provided src/dst IPs
  • If it is not a connectivity issue:
    • Describe the steps taken so far to analyze the logs from networking components (cluster-network-operator, OVNK, SDN, openvswitch, ovs-configure etc) and the actual component where the issue was seen based on the attached must-gather. Please attach snippets of relevant logs around the window when problem has happened if any.

• When showing the results from commands, include the entire command in the output.  
• For OCPBUGS in which the issue has been identified, label with “sbr-triaged”
• For OCPBUGS in which the issue has not been identified and needs Engineering help for root cause, label with “sbr-untriaged”
• Do not set the priority, that is owned by Engineering and will be set when the bug is evaluated
• Note: bugs that do not meet these minimum standards will be closed with label “SDN-Jira-template”
• For guidance on using this template please see
  OCPBUGS Template Training for Networking  components