<p>I am running command <strong>kubectl top nodes</strong> and getting error : </p>

<pre><code>node@kubemaster:~/Desktop/metric$ kubectl top nodes
Error from server (ServiceUnavailable): the server is currently unable to handle the request (get nodes.metrics.k8s.io)
</code></pre>

<p>Metric Server pod is running with following params : </p>

<pre><code>    command:
    - /metrics-server
    - --metric-resolution=30s
    - --requestheader-allowed-names=aggregator
    - --kubelet-insecure-tls
    - --kubelet-preferred-address-types=InternalIP,Hostname,InternalDNS,ExternalDNS,ExternalIP
</code></pre>

<p>Most of the answer I am getting is the above params,
Still getting error</p>

<pre><code>E0601 18:33:22.012798       1 manager.go:111] unable to fully collect metrics: [unable to fully scrape metrics from source kubelet_summary:kubemaster: unable to fetch metrics from Kubelet kubemaster (192.168.56.30): Get https://192.168.56.30:10250/stats/summary?only_cpu_and_memory=true: context deadline exceeded, unable to fully scrape metrics from source kubelet_summary:kubenode1: unable to fetch metrics from Kubelet kubenode1 (192.168.56.31): Get https://192.168.56.31:10250/stats/summary?only_cpu_and_memory=true: dial tcp 192.168.56.31:10250: i/o timeout]
</code></pre>

<p>I have deployed metric server using : </p>

<pre><code>kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.3.6/components.yaml
</code></pre>

<p>What am I missing?
Using Calico for Pod Networking</p>

<p>On github page of metric server under FAQ: </p>

<pre><code>[Calico] Check whether the value of CALICO_IPV4POOL_CIDR in the calico.yaml conflicts with the local physical network segment. The default: 192.168.0.0/16.
</code></pre>

<p>Could this be the reason. Can someone explains this to me.</p>

<p>I have setup Calico using : 
kubectl apply -f <a href="https://docs.projectcalico.org/v3.14/manifests/calico.yaml" rel="noreferrer">https://docs.projectcalico.org/v3.14/manifests/calico.yaml</a></p>

<p>My Node Ips are : 192.168.56.30  / 192.168.56.31 / 192.168.56.32</p>

<p>I have initiated the cluster with --pod-network-cidr=20.96.0.0/12. So my pods Ip are 20.96.205.192 and so on.</p>

<p>Also getting this in apiserver logs</p>

<pre><code>E0601 19:29:59.362627       1 available_controller.go:420] v1beta1.metrics.k8s.io failed with: failing or missing response from https://10.100.152.145:443/apis/metrics.k8s.io/v1beta1: Get https://10.100.152.145:443/apis/metrics.k8s.io/v1beta1: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
</code></pre>

<p>where 10.100.152.145 is IP of service/metrics-server(ClusterIP)</p>

<p>Surprisingly it works on another cluster with Node Ip in 172.16.0.0 range.
Rest everything is same. Setup using kudeadm, Calico, same pod cidr</p>

<p>It started working after I edited the metrics-server deployment yaml config to include a DNS policy.</p>
<p><strong>hostNetwork: true</strong></p>
<p><img src="https://i.stack.imgur.com/8nOBy.png" alt="Click here to view the image description " /></p>
<p>Refer to the link below:
<a href="https://www.linuxsysadmins.com/service-unavailable-kubernetes-metrics/" rel="noreferrer">https://www.linuxsysadmins.com/service-unavailable-kubernetes-metrics/</a></p>
