I am new to kubernetes and trying to setup my testing cluster with one master and two worker nodes on debian 9 virtual machines. so far I have installed kubectl, kubeadm and kubelet on all three nodes along with all the basic requirements. I have also installed Docker Version 17.03.

I am facing problem when I am trying to join my worker node to master node.

   root@Minion1:~# kubeadm join 10.0.2.15:6443 --token kd2o6a.aklftqmvp55m87uf --discovery-token-ca-cert-hash sha256:29bc80e3c298e68077468f00472ae9944597f68374122a2d92e3713262bcf160
    [preflight] Running pre-flight checks.
        [WARNING FileExisting-crictl]: crictl not found in system path
    Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
    [discovery] Trying to connect to API Server "10.0.2.15:6443"
    [discovery] Created cluster-info discovery client, requesting info from "https://10.0.2.15:6443"
[discovery] Failed to request cluster info, will try again: [Get https://10.0.2.15:6443/api/v1/namespaces/kube-public/configmaps/cluster-info: dial tcp 10.0.2.15:6443: getsockopt: connection refused]

Here is the kubeadm init step result :

 root@Master:/home/kube# kubeadm init
[init] Using Kubernetes version: v1.10.13
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
[WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get [github.com/kubernetes-incubator/cri-tools/cmd/crictl](http://github.com/kubernetes-incubator/cri-tools/cmd/crictl)
[preflight] Starting the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.0.2.15]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated sa key and public key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [localhost] and IPs [127.0.0.1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [master] and IPs [10.0.2.15]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[controlplane] Wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] Wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] Wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] Waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests".
[init] This might take a minute or longer if the control plane images have to be pulled.
[apiclient] All control plane components are healthy after 24.505250 seconds
[uploadconfig] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[markmaster] Will mark node master as master by adding a label and a taint
[markmaster] Master master tainted and labelled with key/value: [node-role.kubernetes.io/master=](http://node-role.kubernetes.io/master=)""
[bootstraptoken] Using token: kd2o6a.aklftqmvp55m87uf
[bootstraptoken] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: kube-dns
[addons] Applied essential addon: kube-proxy

Your Kubernetes master has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/

You can now join any number of machines by running the following on each node
as root:

kubeadm join [10.0.2.15:6443](http://10.0.2.15:6443) --token kd2o6a.aklftqmvp55m87uf --discovery-token-ca-cert-hash sha256:29bc80e3c298e68077468f00472ae9944597f68374122a2d92e3713262bcf160

Also, on master node I am not able to run any kubectl commands using root user, but I can use them with other user... is this normal ?

Here are the network connectivity checks between master and worker node.

root@Minion1:~# ping 10.0.2.15
PING 10.0.2.15 (10.0.2.15) 56(84) bytes of data.
64 bytes from 10.0.2.15: icmp_seq=1 ttl=64 time=0.068 ms
64 bytes from 10.0.2.15: icmp_seq=2 ttl=64 time=0.091 ms
64 bytes from 10.0.2.15: icmp_seq=3 ttl=64 time=0.094 ms
^C
--- 10.0.2.15 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2033ms
rtt min/avg/max/mdev = 0.068/0.084/0.094/0.013 ms


root@Master:/home/kube# netstat -ntplu | grep 6443
tcp6       0      0 :::6443                 :::*                    LISTEN      21075/kube-apiserve

How can I join my worker nodes to master ? Is there anything I can troubleshoot to get rid of this problem.

Thanks for the help..