建议直接使用yum安装flanneld，除非对版本有特殊需求，默认安装的是0.7.1版本的flannel。

    service配置文件。

    1. [Unit]
    2. Description=Flanneld overlay address etcd agent
    3. After=network.target
    4. After=network-online.target
    5. Wants=network-online.target
    6. After=etcd.service
    7. Before=docker.service
    9. [Service]
    10. Type=notify
    11. EnvironmentFile=/etc/sysconfig/flanneld
    12. EnvironmentFile=-/etc/sysconfig/docker-network
    13. ExecStart=/usr/bin/flanneld-start \
    14.   -etcd-endpoints=${FLANNEL_ETCD_ENDPOINTS} \
    15.   -etcd-prefix=${FLANNEL_ETCD_PREFIX} \
    16.   $FLANNEL_OPTIONS
    17. ExecStartPost=/usr/libexec/flannel/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/docker
    18. Restart=on-failure
    20. [Install]
    21. WantedBy=multi-user.target
    22. RequiredBy=docker.service

    /etc/sysconfig/flanneld配置文件：

    在etcd中创建网络配置

    执行下面的命令为docker分配IP地址段。

    1.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    2.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
    3.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    4.   mkdir /kube-centos/network
    5. etcdctl --endpoints=https://172.20.0.113:2379,https://172.20.0.114:2379,https://172.20.0.115:2379 \
    6.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    7.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
    8.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    9.   mk /kube-centos/network/config '{"Network":"172.30.0.0/16","SubnetLen":24,"Backend":{"Type":"vxlan"}}'

    如果你要使用host-gw模式，可以直接将vxlan改成host-gw即可。

    启动flannel

    现在查询etcd中的内容可以看到：

    1. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
    2.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    3.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
    4.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    5.   ls /kube-centos/network/subnets
    6. /kube-centos/network/subnets/172.30.14.0-24
    7. /kube-centos/network/subnets/172.30.38.0-24
    8. /kube-centos/network/subnets/172.30.46.0-24
    10. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
    11.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    13.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    14. { "Network": "172.30.0.0/16", "SubnetLen": 24, "Backend": { "Type": "vxlan" } }
    16. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
    17.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    18.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
    19.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    20.   get /kube-centos/network/subnets/172.30.14.0-24
    21. {"PublicIP":"172.20.0.114","BackendType":"vxlan","BackendData":{"VtepMAC":"56:27:7d:1c:08:22"}}
    23. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
    24.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    25.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
    26.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    27.   get /kube-centos/network/subnets/172.30.38.0-24
    28. {"PublicIP":"172.20.0.115","BackendType":"vxlan","BackendData":{"VtepMAC":"12:82:83:59:cf:b8"}}
    30. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
    31.   --ca-file=/etc/kubernetes/ssl/ca.pem \
    32.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
    33.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
    34.   get /kube-centos/network/subnets/172.30.46.0-24

    如果可以查看到以上内容证明flannel已经安装完成，下一步是在node节点上安装和配置docker、kubelet、kube-proxy等，请参考下一节。