K
Q

x509 certificate signed by unknown authority- Kubernetes

4/29/2016

I am configuring Kubernetes cluster with 2 nodes in coreos as described in https://coreos.com/kubernetes/docs/latest/getting-started.html without flannel. Both servers are in same network.

But I am getting: x509: certificate signed by unknown authority (possibly because of "crypto/rsa: verification error" while trying to verify candidate authority certificate "kube-ca") while running kubelet in worker.

I configured the TLS cerficates properly on both the servers as discussed in doc.

The master node is working fine. And the kubectl is able to fire containers and pods in master.

Ques 1: Ho to fix this problem?

Ques 2: Is there any way to configure cluster without TLS certificates.?

Coreos version:
VERSION=899.15.0
VERSION_ID=899.15.0
BUILD_ID=2016-04-05-1035
PRETTY_NAME="CoreOS 899.15.0"

Etcd conf:

 $ etcdctl member list          
ce2a822cea30bfca: name=78c2c701d4364a8197d3f6ecd04a1d8f peerURLs=http://localhost:2380,http://localhost:7001 clientURLs=http://172.24.0.67:2379

Master: kubelet.service:

[Service]
ExecStartPre=/usr/bin/mkdir -p /etc/kubernetes/manifests
Environment=KUBELET_VERSION=v1.2.2_coreos.0
ExecStart=/opt/bin/kubelet-wrapper \
  --api-servers=http://127.0.0.1:8080 \
  --register-schedulable=false \
  --allow-privileged=true \
  --config=/etc/kubernetes/manifests \
  --hostname-override=172.24.0.67 \
  --cluster-dns=10.3.0.10 \
  --cluster-domain=cluster.local
Restart=always
RestartSec=10
[Install]
WantedBy=multi-user.target

Master: kube-controller.yaml

apiVersion: v1
kind: Pod
metadata:
  name: kube-controller-manager
  namespace: kube-system
spec:
  hostNetwork: true
  containers:
  - name: kube-controller-manager
    image: quay.io/coreos/hyperkube:v1.2.2_coreos.0
    command:
    - /hyperkube
    - controller-manager
    - --master=http://127.0.0.1:8080
    - --leader-elect=true 
    - --service-account-private-key-file=/etc/kubernetes/ssl/apiserver-key.pem
    - --root-ca-file=/etc/kubernetes/ssl/ca.pem
    livenessProbe:
      httpGet:
        host: 127.0.0.1
        path: /healthz
        port: 10252
      initialDelaySeconds: 15
      timeoutSeconds: 1
    volumeMounts:
    - mountPath: /etc/kubernetes/ssl
      name: ssl-certs-kubernetes
      readOnly: true
    - mountPath: /etc/ssl/certs
      name: ssl-certs-host
      readOnly: true
  volumes:
  - hostPath:
      path: /etc/kubernetes/ssl
    name: ssl-certs-kubernetes
  - hostPath:
      path: /usr/share/ca-certificates
    name: ssl-certs-host

Master: kube-proxy.yaml

apiVersion: v1
kind: Pod
metadata:
  name: kube-proxy
  namespace: kube-system
spec:
  hostNetwork: true
  containers:
  - name: kube-proxy
    image: quay.io/coreos/hyperkube:v1.2.2_coreos.0
    command:
    - /hyperkube
    - proxy
    - --master=http://127.0.0.1:8080
    securityContext:
      privileged: true
    volumeMounts:
    - mountPath: /etc/ssl/certs
      name: ssl-certs-host
      readOnly: true
  volumes:
  - hostPath:
      path: /usr/share/ca-certificates
    name: ssl-certs-host

Master: kube-apiserver.yaml

apiVersion: v1
kind: Pod
metadata:
  name: kube-apiserver
  namespace: kube-system
spec:
  hostNetwork: true
  containers:
  - name: kube-apiserver
    image: quay.io/coreos/hyperkube:v1.2.2_coreos.0
    command:
    - /hyperkube
    - apiserver
    - --bind-address=0.0.0.0
    - --etcd-servers=http://172.24.0.67:2379
    - --allow-privileged=true
    - --service-cluster-ip-range=10.3.0.0/24
    - --secure-port=443
    - --advertise-address=172.24.0.67
    - --admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ServiceAccount,ResourceQuota
    - --tls-cert-file=/etc/kubernetes/ssl/apiserver.pem
    - --tls-private-key-file=/etc/kubernetes/ssl/apiserver-key.pem
    - --client-ca-file=/etc/kubernetes/ssl/ca.pem
    - --service-account-key-file=/etc/kubernetes/ssl/apiserver-key.pem
    ports:
    - containerPort: 443
      hostPort: 443
      name: https
    - containerPort: 8080
      hostPort: 8080
      name: local
    volumeMounts:
    - mountPath: /etc/kubernetes/ssl
      name: ssl-certs-kubernetes
      readOnly: true
    - mountPath: /etc/ssl/certs
      name: ssl-certs-host
      readOnly: true
  volumes:
  - hostPath:
      path: /etc/kubernetes/ssl
    name: ssl-certs-kubernetes
  - hostPath:
      path: /usr/share/ca-certificates
    name: ssl-certs-host

Master: kube-scheduler.yaml

apiVersion: v1
kind: Pod
metadata:
  name: kube-scheduler
  namespace: kube-system
spec:
  hostNetwork: true
  containers:
  - name: kube-scheduler
    image: quay.io/coreos/hyperkube:v1.2.2_coreos.0
    command:
    - /hyperkube
    - scheduler
    - --master=http://127.0.0.1:8080
    - --leader-elect=true
    livenessProbe:
      httpGet:
        host: 127.0.0.1
        path: /healthz
        port: 10251
      initialDelaySeconds: 15
      timeoutSeconds: 1

Slave: kubelet.service

[Service]
ExecStartPre=/usr/bin/mkdir -p /etc/kubernetes/manifests

Environment=KUBELET_VERSION=v1.2.2_coreos.0 
ExecStart=/opt/bin/kubelet-wrapper \
  --api-servers=https://172.24.0.67:443 \
  --register-node=true \
  --allow-privileged=true \
  --config=/etc/kubernetes/manifests \
  --hostname-override=172.24.0.63 \
  --cluster-dns=10.3.0.10 \
  --cluster-domain=cluster.local \
  --kubeconfig=/etc/kubernetes/worker-kubeconfig.yaml \
  --tls-cert-file=/etc/kubernetes/ssl/worker.pem \
  --tls-private-key-file=/etc/kubernetes/ssl/worker-key.pem
Restart=always
RestartSec=10
[Install]
WantedBy=multi-user.target

Slave: kube-proxy.yaml

apiVersion: v1
kind: Pod
metadata:
  name: kube-proxy
  namespace: kube-system
spec:
  hostNetwork: true
  containers:
  - name: kube-proxy
    image: quay.io/coreos/hyperkube:v1.2.2_coreos.0
    command:
    - /hyperkube
    - proxy
    - --master=https://172.24.0.67:443
    - --kubeconfig=/etc/kubernetes/worker-kubeconfig.yaml
    - --proxy-mode=iptables
    securityContext:
      privileged: true
    volumeMounts:
      - mountPath: /etc/ssl/certs
        name: "ssl-certs"
      - mountPath: /etc/kubernetes/worker-kubeconfig.yaml
        name: "kubeconfig"
        readOnly: true
      - mountPath: /etc/kubernetes/ssl
        name: "etc-kube-ssl"
        readOnly: true
  volumes:
    - name: "ssl-certs"
      hostPath:
        path: "/usr/share/ca-certificates"
    - name: "kubeconfig"
      hostPath:
        path: "/etc/kubernetes/worker-kubeconfig.yaml"
    - name: "etc-kube-ssl"
      hostPath:
        path: "/etc/kubernetes/ssl"
-- Nakshatra
coreos
docker
kubernetes

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4 Answers

11/24/2017

Well, to answer your first question I think you have to do a few things to resolve your problem.

First, run the command given in this link : kubernetes.io/docs/setup/independent/create-cluster-kubeadm‌​/…

Complete with those commands :

  • mkdir -p $HOME/.kube
  • sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  • sudo chown $(id -u):$(id -g) $HOME/.kube/config .This admin.conf should be known to kubectl so as to work properly.
-- Abhay Dwivedi
Source: StackOverflow
1/2/2020

From [kubernetes][1] official site:

  1. Verify that the $HOME/.kube/config file contains a valid certificate, and regenerate a certificate

  2. Unset the KUBECONFIG environment variable using:

    unset KUBECONFIG

    Or set it to the default KUBECONFIG location:

    export KUBECONFIG=/etc/kubernetes/admin.conf

  3. Another workaround is to overwrite the existing kubeconfig for the “admin” user:

   mkdir $HOME/.kube
   sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
   sudo chown $(id -u):$(id -g) $HOME/.kube/config```


**Reference:** [official site link reference][2]

[1]: https://kubernetes.io/
[2]: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/troubleshooting-kubeadm/
-- Umar Hayat
Source: StackOverflow
2/17/2019
mkdir -p $HOME/.kube   
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config   
sudo chown $(id -u):$(id -g) $HOME/.kube/config
-- yasin lachini
Source: StackOverflow
3/14/2018

Please see this as a reference and maybe help you resolve your issue by exporting your certs:

kops export kubecfg "your cluster-name"
export KOPS_STATE_STORE=s3://"paste your S3 store"

Hope that will help.

-- JohnBegood
Source: StackOverflow