<p>I have install metrics server on my local k8s cluster on VirtualBox using <a href="https://github.com/kubernetes-sigs/metrics-server#installation" rel="noreferrer">https://github.com/kubernetes-sigs/metrics-server#installation</a></p>
<p>But the metrics server pod is in</p>
<pre><code>metrics-server-844d9574cf-bxdk7      0/1     CrashLoopBackOff   28         12h     10.46.0.1      kubenode02   &lt;none&gt;           &lt;none&gt;
</code></pre>
<p>Events from the pod describe</p>
<pre><code>Events:
  Type     Reason          Age                    From                 Message
  ----     ------          ----                   ----                 -------
  Normal   Scheduled       &lt;unknown&gt;                                   Successfully assigned kube-system/metrics-server-844d9574cf-bxdk7 to kubenode02
  Normal   Created         12h (x3 over 12h)      kubelet, kubenode02  Created container metrics-server
  Normal   Started         12h (x3 over 12h)      kubelet, kubenode02  Started container metrics-server
  Normal   Killing         12h (x2 over 12h)      kubelet, kubenode02  Container metrics-server failed liveness probe, will be restarted
  Warning  Unhealthy       12h (x7 over 12h)      kubelet, kubenode02  Liveness probe failed: HTTP probe failed with statuscode: 500
  Warning  Unhealthy       12h (x7 over 12h)      kubelet, kubenode02  Readiness probe failed: HTTP probe failed with statuscode: 500
  Normal   Pulled          12h (x7 over 12h)      kubelet, kubenode02  Container image &quot;k8s.gcr.io/metrics-server/metrics-server:v0.4.0&quot; already present on machine
  Warning  BackOff         12h (x35 over 12h)     kubelet, kubenode02  Back-off restarting failed container
  Normal   SandboxChanged  55m (x22 over 59m)     kubelet, kubenode02  Pod sandbox changed, it will be killed and re-created.
  Normal   Pulled          55m                    kubelet, kubenode02  Container image &quot;k8s.gcr.io/metrics-server/metrics-server:v0.4.0&quot; already present on machine
  Normal   Created         55m                    kubelet, kubenode02  Created container metrics-server
  Normal   Started         55m                    kubelet, kubenode02  Started container metrics-server
  Warning  Unhealthy       29m (x35 over 55m)     kubelet, kubenode02  Liveness probe failed: HTTP probe failed with statuscode: 500
  Warning  BackOff         4m45s (x202 over 54m)  kubelet, kubenode02  Back-off restarting failed container
</code></pre>
<p>Logs from the deployment of metrics is as follows using <strong>kubectl logs deployment/metrics-server -n kube-system</strong></p>
<pre><code>E1110 12:56:25.249873       1 pathrecorder.go:107] registered &quot;/metrics&quot; from goroutine 1 [running]:
runtime/debug.Stack(0x1942e80, 0xc0006e8db0, 0x1bb58b5)
        /usr/local/go/src/runtime/debug/stack.go:24 +0x9d
k8s.io/apiserver/pkg/server/mux.(*PathRecorderMux).trackCallers(0xc0004f73b0, 0x1bb58b5, 0x8)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/mux/pathrecorder.go:109 +0x86
k8s.io/apiserver/pkg/server/mux.(*PathRecorderMux).Handle(0xc0004f73b0, 0x1bb58b5, 0x8, 0x1e96f00, 0xc0005dc8d0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/mux/pathrecorder.go:173 +0x84
k8s.io/apiserver/pkg/server/routes.MetricsWithReset.Install(0xc0004f73b0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/routes/metrics.go:43 +0x5d
k8s.io/apiserver/pkg/server.installAPI(0xc00000a1e0, 0xc00013d8c0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/config.go:711 +0x6c
k8s.io/apiserver/pkg/server.completedConfig.New(0xc00013d8c0, 0x1f099c0, 0xc000697090, 0x1bbdb5a, 0xe, 0x1ef29e0, 0x2cef248, 0x0, 0x0, 0x0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/config.go:657 +0xb45
sigs.k8s.io/metrics-server/pkg/server.Config.Complete(0xc00013d8c0, 0xc00013cb40, 0xc00013d680, 0xdf8475800, 0xc92a69c00, 0x0, 0x0, 0xdf8475800)
        /go/src/sigs.k8s.io/metrics-server/pkg/server/config.go:52 +0x312
sigs.k8s.io/metrics-server/cmd/metrics-server/app.runCommand(0xc0001140b0, 0xc0000a65a0, 0x0, 0x0)
        /go/src/sigs.k8s.io/metrics-server/cmd/metrics-server/app/start.go:66 +0x157
sigs.k8s.io/metrics-server/cmd/metrics-server/app.NewMetricsServerCommand.func1(0xc000618b00, 0xc0002c3a80, 0x0, 0x4, 0x0, 0x0)
        /go/src/sigs.k8s.io/metrics-server/cmd/metrics-server/app/start.go:37 +0x33
github.com/spf13/cobra.(*Command).execute(0xc000618b00, 0xc000100060, 0x4, 0x4, 0xc000618b00, 0xc000100060)
        /go/pkg/mod/github.com/spf13/cobra@v1.0.0/command.go:842 +0x453
github.com/spf13/cobra.(*Command).ExecuteC(0xc000618b00, 0xc00012a120, 0x0, 0x0)
        /go/pkg/mod/github.com/spf13/cobra@v1.0.0/command.go:950 +0x349
github.com/spf13/cobra.(*Command).Execute(...)
        /go/pkg/mod/github.com/spf13/cobra@v1.0.0/command.go:887
main.main()
        /go/src/sigs.k8s.io/metrics-server/cmd/metrics-server/metrics-server.go:38 +0xae
I1110 12:56:25.384926       1 secure_serving.go:197] Serving securely on [::]:4443
I1110 12:56:25.384972       1 requestheader_controller.go:169] Starting RequestHeaderAuthRequestController
I1110 12:56:25.384979       1 shared_informer.go:240] Waiting for caches to sync for RequestHeaderAuthRequestController
I1110 12:56:25.384996       1 dynamic_serving_content.go:130] Starting serving-cert::/tmp/apiserver.crt::/tmp/apiserver.key
I1110 12:56:25.385018       1 tlsconfig.go:240] Starting DynamicServingCertificateController
I1110 12:56:25.385069       1 configmap_cafile_content.go:202] Starting client-ca::kube-system::extension-apiserver-authentication::client-ca-file
I1110 12:56:25.385083       1 shared_informer.go:240] Waiting for caches to sync for client-ca::kube-system::extension-apiserver-authentication::client-ca-file
I1110 12:56:25.385105       1 configmap_cafile_content.go:202] Starting client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file
I1110 12:56:25.385117       1 shared_informer.go:240] Waiting for caches to sync for client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file
E1110 12:56:25.385521       1 server.go:132] unable to fully scrape metrics: [unable to fully scrape metrics from node kubenode02: unable to fetch metrics from node kubenode02: Get &quot;https://192.168.56.4:10250/stats/summary?only_cpu_and_memory=true&quot;: x509: cannot validate certificate for 192.168.56.4 because it doesn't contain any IP SANs, unable to fully scrape metrics from node kubenode01: unable to fetch metrics from node kubenode01: Get &quot;https://192.168.56.3:10250/stats/summary?only_cpu_and_memory=true&quot;: x509: cannot validate certificate for 192.168.56.3 because it doesn't contain any IP SANs, unable to fully scrape metrics from node kubemaster: unable to fetch metrics from node kubemaster: Get &quot;https://192.168.56.2:10250/stats/summary?only_cpu_and_memory=true&quot;: x509: cannot validate certificate for 192.168.56.2 because it doesn't contain any IP SANs]
I1110 12:56:25.485100       1 shared_informer.go:247] Caches are synced for RequestHeaderAuthRequestController 
I1110 12:56:25.485359       1 shared_informer.go:247] Caches are synced for client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file 
I1110 12:56:25.485398       1 shared_informer.go:247] Caches are synced for client-ca::kube-system::extension-apiserver-authentication::client-ca-file
</code></pre>

Himadri Ganguly
<p>The error is due to the <strong>self-signed TLS certificate</strong>. So adding <strong>- --kubelet-insecure-tls</strong> to the <strong>components.yaml</strong> and re-applying it to the K8s cluster fixes the issue.</p>
<p><strong>Ref:-</strong> <a href="https://github.com/kubernetes-sigs/metrics-server#configuration" rel="noreferrer">https://github.com/kubernetes-sigs/metrics-server#configuration</a></p>
