Error - Failed to ping endpoint; Unable to add Harbor as a New Registry Endpoint in VKS 3.5.1 due to Spherelet instability

Products

• VMware vSphere Kubernetes Service

Issue/Introduction

In the Harbor UI after going to Administration - Registries - and when attempting to add a New Registry Endpoint for replication, the operation fails with a "Failed to ping endpoint" error as seen in the below image. This occurs even when network connectivity between the components is verified as open.



Note: You must be logged in with an account that has Harbor System Administrator privileges to view the Administration menu and configure registry endpoints.

Environment

VMware vSphere Kubernetes Service (VKS) 3.5.1

Harbor Registry / Spherelet Service

Cause

Harbor UI reports "Failed to ping endpoint" when configuring a replication endpoint.
Manual network verification (e.g., curl to the Harbor FQDN over the expected interface) confirms the path is open, but the communication components fail to acknowledge the endpoint.
No network timeouts are captured in curl check the service simply fails to process the request.

The spherelet service on the ESXi host(s) may become unstable or hung. Since the Harbor registry communication depends on the health of host services, a stale or malfunctioning spherelet service blocks the execution of probes required to verify external registry endpoints.

Resolution

To resolve this issue, restart the spherelet service on the affected ESXi hosts to clear the stale state.

1. Log in to the affected ESXi host(s) via SSH, see KB 319389 

2. Stop the spherelet service using command below:

/etc/init.d/spherelet stop

3. Start the spherelet service using below command:

/etc/init.d/spherelet start

4. Verify the service status:

/etc/init.d/spherelet status

Once the service is running correctly, retry adding the Registry Endpoint in the Harbor UI.