前言
k8s 集群 node节点报错：The connection to the server localhost:8080 was refused - did you specify the right host or port?
通过 kubectl get nodes 查看集群的情况，出现了报错，内容如下：
$ kubectl get pod
E0529 02:28:59.776677 415799 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp 127.0.0.1:8080: connect: connection refused
E0529 02:28:59.777439 415799 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp 127.0.0.1:8080: connect: connection refused
E0529 02:28:59.778983 415799 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp 127.0.0.1:8080: connect: connection refused
E0529 02:28:59.780888 415799 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp 127.0.0.1:8080: connect: connection refused
E0529 02:28:59.782303 415799 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp 127.0.0.1:8080: connect: connection refused
The connection to the server localhost:8080 was refused - did you specify the right host or port?
原因：
kubectl 默认从 ~/.kube/config 配置文件获取访问 kube-apiserver 地址、证书、用户名等信息，如果没有配置该文件会读取默值，即 localhost:8080，而本机的 localhost:8080 没有服务因而报 The connection to the server localhost:8080 was refused - did you specify the right host or port?
解决
先检查当前 kubelct 配置加载信息，kubectl config view，如果为空需要检查 /etc/kubernetes/admin.conf 配置文件和 $HOME/.kube/config 配置，如果不存在，需要复制master节点上的配置到当前节点上
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
Alternatively, if you are the root user, you can run:
export KUBECONFIG=/etc/kubernetes/admin.conf
指定配置文件路径
如果你的配置文件不在默认路径，可以通过 KUBECONFIG 环境变量指定路径，或者在命令行中使用 --kubeconfig 选项。
使用 KUBECONFIG 环境变量
export KUBECONFIG=/path/to/your/kubeconfig
kubectl config view
使用 --kubeconfig 选项
kubectl --kubeconfig=/etc/kubernetes/admin.conf config view