安装flannel网络插件

所有的node节点都需要安装网络插件才能让所有的Pod加入到同一个局域网中，本文是安装flannel网络插件的参考文档。

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。

  1. yum install -y flannel

service配置文件/usr/lib/systemd/system/flanneld.service。

  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：

  1. # Flanneld configuration options  
  3. # etcd url location.  Point this to the server where etcd runs
  4. FLANNEL_ETCD_ENDPOINTS="https://172.20.0.113:2379,https://172.20.0.114:2379,https://172.20.0.115:2379"
  6. # etcd config key.  This is the configuration key that flannel queries
  7. # For address range assignment
  8. FLANNEL_ETCD_PREFIX="/kube-centos/network"
  10. # Any additional options that you want to pass
  11. FLANNEL_OPTIONS="-etcd-cafile=/etc/kubernetes/ssl/ca.pem -etcd-certfile=/etc/kubernetes/ssl/kubernetes.pem -etcd-keyfile=/etc/kubernetes/ssl/kubernetes-key.pem"

如果是多网卡（例如vagrant环境），则需要在FLANNEL_OPTIONS中增加指定的外网出口的网卡，例如-iface=eth2

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. etcdctl --endpoints=https://172.20.0.113:2379,https://172.20.0.114:2379,https://172.20.0.115:2379 \
  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.   mkdir /kube-centos/network
  6. etcdctl --endpoints=https://172.20.0.113:2379,https://172.20.0.114:2379,https://172.20.0.115:2379 \
  7.   --ca-file=/etc/kubernetes/ssl/ca.pem \
  8.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
  9.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
  10.   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。

注：参考网络和集群性能测试那节，最终我们使用的host-gw模式，关于flannel支持的backend模式见：https://github.com/coreos/flannel/blob/master/Documentation/backends.md。

启动flannel

  1. systemctl daemon-reload
  2. systemctl enable flanneld
  3. systemctl start flanneld
  4. systemctl status flanneld

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 \
  12.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
  13.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
  14.   get /kube-centos/network/config
  15. { "Network": "172.30.0.0/16", "SubnetLen": 24, "Backend": { "Type": "vxlan" } }
  17. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
  18.   --ca-file=/etc/kubernetes/ssl/ca.pem \
  19.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
  20.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
  21.   get /kube-centos/network/subnets/172.30.14.0-24
  22. {"PublicIP":"172.20.0.114","BackendType":"vxlan","BackendData":{"VtepMAC":"56:27:7d:1c:08:22"}}
  24. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
  25.   --ca-file=/etc/kubernetes/ssl/ca.pem \
  26.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
  27.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
  28.   get /kube-centos/network/subnets/172.30.38.0-24
  29. {"PublicIP":"172.20.0.115","BackendType":"vxlan","BackendData":{"VtepMAC":"12:82:83:59:cf:b8"}}
  31. $etcdctl --endpoints=${ETCD_ENDPOINTS} \
  32.   --ca-file=/etc/kubernetes/ssl/ca.pem \
  33.   --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
  34.   --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
  35.   get /kube-centos/network/subnets/172.30.46.0-24
  36. {"PublicIP":"172.20.0.113","BackendType":"vxlan","BackendData":{"VtepMAC":"e6:b2:fd:f6:66:96"}}

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，请参考下一节部署node节点。