kubernetes can not join workers centos 7 - kubernetes

Question

My issue is that I can not connect between our machines (master and slaves)
My connection command should be
kubeadm join xxx:xxx:xxx:xxx:6443 --token a72x22.ofmqdjyzi7ot4l70 --discovery-token-ca-cert-hash sha256:3cfd9ddb1e655ef2172c12d914e2bb001434cc4c8a756919a7a6a9f0603e3131
I have been execute
echo 1 >/proc/sys/net/bridge/bridge-nf-call-iptables
echo 1 >/proc/sys/net/ipv4/ip_forward
swapoff -a
and I got the error
[kubelet-start] Downloading configuration for the kubelet from the
"kubelet-config-1.15" ConfigMap in the kube-system namespace error
execution phase kubelet-start: configmaps "kubelet-config-1.15" is
forbidden: User "system:bootstrap:a61x22" can
not get resource "configmaps" in API group "" in the namespace
"kube-system"
master kubectl version
Client Version: version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.0", GitCommit:"e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529", GitTreeState:"clean", BuildDate:"2019-06-19T16:40:16Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"} Server Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.3", GitCommit:"5e53fd6bc17c0dec8434817e69b04a25d8ae0ff0", GitTreeState:"clean", BuildDate:"2019-06-06T01:36:19Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"}
slaves kubectl version
Client Version: version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.0", GitCommit:"e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529", GitTreeState:"clean", BuildDate:"2019-06-19T16:40:16Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"}
The connection to the server localhost:8080 was refused - did you specify the right host or port?
maybe my issue is connected to the host or port?
how can I solve this issue?

Answer 1

Check if configmaps "kubelet-config-1.15" exists with the command below.
kubectl -n kube-system get configmap kubelet-config-1.15
Maybe your master is at version 1.14 and your new node downloaded a kubelet version 1.15.
In that case your configmap didn't exists and you have a configmap kubelet-config-1.14.
Upgrade your master node to v 1.15 or install kubernetes v1.14 into your worker node.
You can see what version your nodes are with
kubectl get nodes
[root#master /]# k get nodes
NAME STATUS ROLES AGE VERSION
master Ready master 32d v1.14.0
node6 Ready 32d v1.14.2
nodo2 Ready 32d v1.14.2