NSX logs show health check warning for node/VIP DNS unable to be checked: "Failed to check DNS entries ... local variable 'ipv6_fqdn_name' referenced before assignment"

Products

• VMware NSX

Issue/Introduction

The below WARNING tracebacks could be seen in the NSX syslog or in Node API server logs (under var/log/nvpapi/api_server.log), when the NSX Manager is configured with CA signed certificate is configured:

NSX #### - [nsx@#### comp="nsx-manager" subcomp="node-mgmt" username="root" level="WARNING"] Failed to check DNS entries 
for VIP with error reason: Traceback (most recent call last):#012 File "/opt/vmware/nsx-node-api/bin/python/management_api/napi/root/alarms/manager_health_event.py", line 200, in 
dual_stack_missing_dns_entry_vip_callback#012 if ipv4_fqdn_name and ipv6_fqdn_name:#012UnboundLocalError: local variable 'ipv6_fqdn_name' referenced before assignment

No alarms are present in the UI indicating DNS issues or Manager/VIP connectivity issues in the environment.

IPv6 is not configured on the Manager nodes or VIP: NSX UI -> System -> Appliances

Management cluster nodes are using CA-signed certificates.

Environment

NSX 4.x

Cause

In certain environments where the Management cluster nodes are using CA-signed certificates, there is an error with the built-in health_event.py script where it may try to resolve IPv6 for a Manager node or VIP where IPv6 is not in-use or configured.

This in turn generates a WARNING log that the IPv6 DNS resolution fails since IPv6 is not configured; this is an expected log given the configuration, however the error is the script checking for IPv6 in the first place.

 

Resolution

This is expected behavior and there is no impact or risk.

The issue is resolved in NSX 9.0+

Additional Information

If there is an alarm in the environment related to DNS/FQDN errors, see Edge/Transport Nodes fail to resolve NSX Manager FQDN with "DNS lookup failed for Manager node" Alarms in NSX Manager UI