Kubernetes集群配置Flannel服务

Posted by     Aeric on Friday, November 30, 2018

TOC

检查 TLS 证书

➜ ls /etc/kubernetes/ssl/
admin-key.pem  admin.pem  ca-key.pem  ca.pem  kube-proxy-key.pem  kube-proxy.pem  kubernetes-key.pem  kubernetes.pem

配置 Flannel 服务

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 v0.7.1 版本的 flannel。

安装 flanneld 服务,具体参考如下:

➜ yum -y install flannel
➜ systemctl start flanneld.service

在起 flanneld 服务之前,我们需要修改 flanneld服务的 Systemd Unit 文件和对应的配置文件

修改 flannel 服务的 systemd unit 文件

➜ cat /usr/lib/systemd/system/flanneld.service

具体内容如下:

[Unit]
Description=Flanneld overlay address etcd agent
After=network.target
After=network-online.target
Wants=network-online.target
After=etcd.service
Before=docker.service

[Service]
Type=notify
EnvironmentFile=/etc/sysconfig/flanneld
EnvironmentFile=-/etc/sysconfig/docker-network
ExecStart=/usr/bin/flanneld-start \
    $FLANNEL_OPTIONS \
    -etcd-endpoints=${FLANNEL_ETCD_ENDPOINTS} \
    -etcd-prefix=${FLANNEL_ETCD_PREFIX}
ExecStartPost=/usr/libexec/flannel/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/docker
Restart=on-failure

[Install]
WantedBy=multi-user.target
RequiredBy=docker.service

完整 flanneld systemd unit 参见 flanneld.service

修改 flannel 服务配置文件

flannel 服务配置文件: /etc/sysconfig/flanneld

# Flanneld configuration options  

# etcd url location.  Point this to the server where etcd runs
#FLANNEL_ETCD_ENDPOINTS="http://127.0.0.1:2379"
FLANNEL_ETCD_ENDPOINTS="https://192.168.8.66:2379,https://192.168.8.67:2379,https://192.168.8.68:2379"

# 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"

完整 flannel 服务配置文件参见: flanneld

flannel 服务的 systemd unit 文件及配置文件修改完成后,就可以启动 flanneld 服务了。

➜ systemctl daemon-reload
➜ systemctl start flanneld.service

在 etcd 中创建网络配置

执行下面的命令为docker分配IP地址段:

➜ etcdctl --endpoints=https://192.168.8.66:2379,https://192.168.8.67:2379,https://192.168.8.68:2379 \
  --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

➜ etcdctl --endpoints=https://192.168.8.66:2379,https://192.168.8.67:2379,https://192.168.8.68:2379 \
  --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":"vxlan"}}'

配置 docker 服务

docker 需要和 flannel 服务在同一个网段内,这样后期才能互通。

docker 服务的安装直接用 yum 包管理工具直接安装即可:

➜ yum -y install docker

配置 docker 服务如下:

➜ systemctl stop docker.service
➜ source  /run/flannel/subnet.env 
➜ docker  daemon  --bip=${FLANNEL_SUBNET}  --mtu=${FLANNEL_MTU} &
➜ ifconfig docker0 $FLANNEL_SUBNET

修改docker服务文件增加如下内容:

EnvironmentFile=-/run/flannel/docker 
EnvironmentFile=-/run/docker_opts.env 
EnvironmentFile=-/run/flannel/subnet.env

配置完成后需要重启 docker 及 flannel 服务。

➜ systemctl daemon-reload
➜ systemctl restart docker.service
➜ systemctl restart flanneld.service

我们在重启 docker 服务的时候可能重启失败,原因一般是 docker 进程还存在,将其杀死再重启既可,可以参考:ps axf | grep docker | grep -v grep | awk '{print "kill -9 " $1}' | sudo sh

查询 etcd 中的内容

docker 和 flannel 服务启动正常后,我们可以参照下面的方式查看 etcd 的内容:

➜ 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
/kube-centos/network/subnets/172.30.78.0-24
/kube-centos/network/subnets/172.30.79.0-24
/kube-centos/network/subnets/172.30.41.0-24

其实 flanneld 和 docker 服务在 master 节点上是非必需的,但是我们建议在 master 节点上同样配置 flanneld 和 docker 服务,因为这样可以很方便的通过 master 节点访问 node 上的服务,例如插件 dashboard 的访问,我们可以通过 api-server 来访问:http://master-ip:8080/ui

master 节点的 flanneld 和 docker 服务安装好后,我们在 master 节点可以 ping 通 nodes 节点的 flanneld 地址,例如:

➜ ping 172.30.41.0
PING 172.30.41.0 (172.30.41.0) 56(84) bytes of data.
64 bytes from 172.30.41.0: icmp_seq=1 ttl=64 time=0.081 ms
^C
--- 172.30.41.0 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.081/0.081/0.081/0.000 ms

[[email protected] ~]# ping 172.30.78.0
PING 172.30.78.0 (172.30.78.0) 56(84) bytes of data.
64 bytes from 172.30.78.0: icmp_seq=1 ttl=64 time=0.648 ms
^C
--- 172.30.78.0 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.648/0.648/0.648/0.000 ms
[[email protected] ~]# ping 172.30.79.0
PING 172.30.79.0 (172.30.79.0) 56(84) bytes of data.
64 bytes from 172.30.79.0: icmp_seq=1 ttl=64 time=0.658 ms

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