I don't think it's a bug. It's not only DefaultBackendManager that can record the backend but all backend managers inherit AddBackend from DefaultBackendStorage. Please reconsider this.

Yes, every backend manager will inherit AddBackend method.

What I wonder is that the DefaultBackendStorage record backend metric through setting their own backends count while the backend metric is belong to proxy server. And the backend managers will overwrite each other's values.

For example, the proxy server has two backend managers. One has three backends and the other has five backends. Now the backend metric will only be one of these tow values while the actual value may be greater than three and smaller than five.

The related codes as following shows:

// SetBackendCount sets the number of backend connection.
func (a *ServerMetrics) SetBackendCount(count int) {
	a.backend.WithLabelValues().Set(float64(count))
}


func (s *DefaultBackendStorage) AddBackend(identifier string, idType pkgagent.IdentifierType, conn agent.AgentService_ConnectServer) Backend {
	// ...
	addedBackend := newBackend(conn)
	// ...
	metrics.Metrics.SetBackendCount(len(s.backends))
	// ...
	return addedBackend
}

Thanks for your explanation, let's go on with your fix. proxy server is designed to support multiple backend managers, though currently only one is used.

/cc @yan-lgtm
/cc @cheftako

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/close

@k8s-triage-robot: Closing this issue.

/assign