node节点需要安装flannel网络插件才能保证所有的pod在一个局域网内通信，直接使用yum安装即可，版本是0.7.1.
1、安装flannel插件：
注意是2个node节点都需要安装，都需要修改service文件和配置文件。
yum install ?flannel -y
2、修改service文件/usr/lib/systemd/system/flanneld.service其内容为：
[Unit]Description=Flanneld overlay address etcd agentAfter=network.targetAfter=network-online.targetWants=network-online.targetAfter=etcd.serviceBefore=docker.service[Service]Type=notifyEnvironmentFile=/etc/sysconfig/flanneldEnvironmentFile=-/etc/sysconfig/docker-networkExecStart=/usr/bin/flanneld-start ??-etcd-endpoints=${FLANNEL_ETCD_ENDPOINTS} ??-etcd-prefix=${FLANNEL_ETCD_PREFIX} ??$FLANNEL_OPTIONSExecStartPost=/usr/libexec/flannel/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/dockerRestart=on-failure[Install]WantedBy=multi-user.targetRequiredBy=docker.service提示:service文件中所有的变量参数都是读取相应的配置文件里面的，所有要保证前后对应。
修改其配置文件/etc/sysconfig/flanneld 内容如下：
# Flanneld configuration options ?# etcd url location. ?Point this to the server where etcd runsFLANNEL_ETCD_ENDPOINTS="https://10.10.90.105:2379,https://10.10.90.106:2379,https://10.10.90.107:2379"# etcd config key. ?This is the configuration key that flannel queries# For address range assignment#FLANNEL_ETCD_PREFIX="/atomic.io/network"FLANNEL_ETCD_PREFIX="/kube-centos/network"# Any additional options that you want to pass#FLANNEL_OPTIONS=""FLANNEL_OPTIONS="-etcd-cafile=/etc/kubernetes/ssl/ca.pem -etcd-certfile=/etc/kubernetes/ssl/kubernetes.pem -etcd-keyfile=/etc/kubernetes/ssl/kubernetes-key.pem"
以上2步是2个node节点都需要做的。
3、在etcd中常见网络配置信息
etcdctl --endpoints=https://10.10.90.105:2379,https://10.10.90.106:2379,https://10.10.90.107:2379 \ ?--ca-file=/etc/kubernetes/ssl/ca.pem ??--cert-file=/etc/kubernetes/ssl/kubernetes.pem ??--key-file=/etc/kubernetes/ssl/kubernetes-key.pem ??mkdir /kube-centos/network#上下是2条命令，在任何节点上创建都行，因为etcd是集群的。etcdctl --endpoints=https://10.10.90.105:2379,https://10.10.90.106:2379,https://10.10.90.107:2379 \ ?--ca-file=/etc/kubernetes/ssl/ca.pem ??--cert-file=/etc/kubernetes/ssl/kubernetes.pem ??--key-file=/etc/kubernetes/ssl/kubernetes-key.pem ??mk /kube-centos/network/config ‘{"Network":"172.30.0.0/16","SubnetLen":24,"Backend":{"Type":"host-gw"}}‘4、启动flannel服务
systemctl daemon-reloadsystemctl enable flanneldsystemctl start flanneldsystemctl status flanneld
5、核对相关配置信息：
[root@c7test_node1 ~]# etcdctl --endpoints=${ETCD_ENDPOINTS} > ??--ca-file=/etc/kubernetes/ssl/ca.pem > ??--cert-file=/etc/kubernetes/ssl/kubernetes.pem > ??--key-file=/etc/kubernetes/ssl/kubernetes-key.pem > ??ls /kube-centos/network/subnets
#输出/kube-centos/network/subnets/172.30.87.0-24/kube-centos/network/subnets/172.30.92.0-24#说明，有几个node就有几个子网络，就有几条记录，我是2个node，分别安装了flannel插件
[root@c7test_node1 ~]# etcdctl --endpoints=${ETCD_ENDPOINTS} \
> --ca-file=/etc/kubernetes/ssl/ca.pem \
> ??--cert-file=/etc/kubernetes/ssl/kubernetes.pem \
> ??--key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
> ??get /kube-centos/network/config
#输出
{"Network":"172.30.0.0/16","SubnetLen":24,"Backend":{"Type":"host-gw"}}
#此处是查看主网络配置
etcdctl --endpoints=${ETCD_ENDPOINTS} --ca-file=/etc/kubernetes/ssl/ca.pem --cert-file=/etc/kubernetes/ssl/kubernetes.pem --key-file=/etc/kubernete s/ssl/kubernetes-key.pem get /kube-centos/network/subnets/172.30.92.0-24
#输出
{"PublicIP":"10.10.90.106","BackendType":"vxlan","BackendData":{"VtepMAC":"26:af:ac:26:47:ad"}}
etcdctl --endpoints=${ETCD_ENDPOINTS} --ca-file=/etc/kubernetes/ssl/ca.pem --cert-file=/etc/kubernetes/ssl/kubernetes.pem --key-file=/etc/kubernete s/ssl/kubernetes-key.pem get /kube-centos/network/subnets/172.30.87.0-24
#输出
{"PublicIP":"10.10.90.107","BackendType":"vxlan","BackendData":{"VtepMAC":"82:6f:58:94:9f:59"}}
如有以上输出即代表flannel插件安装配置成功，下一篇文章开始安装node节点。
Kubernetes（K8s）安装部署过程（五）--安装flannel网络插件
原文地址：https://www.cnblogs.com/netsa/p/8203173.html