[root@master k8s]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml
The connection to the server raw.githubusercontent.com was refused - did you specify the right host or port?
[root@master k8s]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
The connection to the server raw.githubusercontent.com was refused - did you specify the right host or port?

基本上是因为连不上外网导致，所以我们添加映射

199.232.68.133 raw.githubusercontent.com

但是还是报错

[root@master k8s]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
[root@master k8s]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused

所以我们采用先下载文件的方式

[root@master k8s]# wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
--2021-09-01 18:46:36--  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
正在解析主机 raw.githubusercontent.com (raw.githubusercontent.com)... 199.232.68.133
正在连接 raw.githubusercontent.com (raw.githubusercontent.com)|199.232.68.133|:443... 已连接。

没有下文了，反复尝试，终于下载成功

[root@master k8s]# wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
--2021-09-01 19:03:14--  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
正在解析主机 raw.githubusercontent.com (raw.githubusercontent.com)... 199.232.68.133
正在连接 raw.githubusercontent.com (raw.githubusercontent.com)|199.232.68.133|:443... 已连接。
已发出 HTTP 请求，正在等待回应... 200 OK
长度：4813 (4.7K) [text/plain]
正在保存至: “kube-flannel.yml”

100%[=====================================================================================>] 4,813       --.-K/s 用时 0s      

2021-09-01 19:03:14 (93.4 MB/s) - 已保存 “kube-flannel.yml” [4813/4813])

[root@master k8s]# ls
kube-flannel.yml

结果应用时又报错

[root@master k8s]# kubectl apply -f kube-flannel.yml 
unable to recognize "kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
unable to recognize "kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
unable to recognize "kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
unable to recognize "kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
unable to recognize "kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
unable to recognize "kube-flannel.yml": Get http://localhost:8080/api?timeout=32s: dial tcp [::1]:8080: connect: connection refused
[root@master k8s]# ll

解决方法

[root@master k8s]#  mkdir -p $HOME/.kube
[root@master k8s]#   sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@master k8s]#   sudo chown $(id -u):$(id -g) $HOME/.kube/config
[root@master k8s]# kubectl apply -f kube-flannel.yml 
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

搞定