error: The connection to the server localhost:8080 was refused - did you specify the right host or port?

In most cases, this error message is displayed when the kubectl configuration of your cluster is not set up correctly.

Basic information

By default ‘kubectl’ configuration file is located in $HOME/.kube/config and contains the following sections:

Cluster information:

• hostname/ip:port of your kubernetes master node with running kube-apiserver

• certificates required to connect to the kube-apiserver

  clusters:
  - cluster:
      certificate-authority-data: REDACTED
      server: https://10.156.0.3:6443
    name: kubernetes

User information:

• User name

• User certificate

  users:
  - name: kubernetes-admin
    user:
      client-certificate-data: REDACTED
      client-key-data: REDACTED

Context information:

• combinations of cluster and user references

• current context that is used if no context is specified in kubectl command line

  contexts:
  - context:
      cluster: kubernetes
      user: kubernetes-admin
    name: kubernetes-admin@kubernetes
  current-context: kubernetes-admin@kubernetes
  kind: Config
  preferences: {}

Usage:

You can view your current kubectl configuration using the following command:

kubectl config view

It is possible to have several configuration files that you can add to the environment variable KUBECONFIG:

export  KUBECONFIG=$KUBECONFIG:config-demo:config-demo-2

You can also specify ‘kubectl’ config file in the command line:

kubectl --kubeconfig path/to/kubectl.conf get nodes

You can export your current kubectl config and use it on another workstation:

kubectl config view --flatten

Articles:

Please find more information about kubectl configuration and usage in the following articles:

• Configure Access to Multiple Clusters
• kubectl Cheat Sheet

How to create:

You can create kubectl configuration manually or as a part of cluster creation process.

Here is how to create kubectl configuration for existing kops cluster( link1, link2 ):

# update cluster will do it automatically after cluster creation. 
# But we expect that if you're part of a team you might share the KOPS_STATE_STORE

# ASSUMPTION:  You have pointed kops to some location where the cluster configurations are stored 
# (I have this in my ~/.bash_profile):
export KOPS_STATE_STORE=s3://example-state-store

# Use kops to get the list of clusters
$ kops get clusters

# Export the configuration of the cluster you care about; this will update your ~/.kube/config file, so kubectl knows about it:
$ kops export kubecfg cluster-foo.example.com

# You can now use kubernetes using the kubectl tool:
$ kubectl get nodes

If you created your cluster using kubeadm, kubectl config is located in /etc/kubernetes/admin.conf on the master node and you can just copy it to your home directory:

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