1、CNI网络插件最主要的功能就是实现POD资源能够跨宿主机是进行能信

#test-nodes1主机无法ping通test-nodes2主机的pod容器

[root@test-nodes1 ~]# kubectl get pods -o wide

NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES

nginx-ds1-qg45q 1/1 Running 0 2d12h 172.7.22.3 test-nodes2.cedarhd.com

nginx-ds1-whnmv 1/1 Running 0 2d12h 172.7.21.3 test-nodes1.cedarhd.com

[root@test-nodes1 ~]# ping 172.7.22.3

PING 172.7.22.3 (172.7.22.3) 56(84) bytes of data.

^C

--- 172.7.22.3 ping statistics ---

8 packets transmitted, 0 received, 100% packet loss, time 6999ms

二、flannel安装

#此操作分别需要在test-nodes1与test-nodes2上操作

[root@test-nodes1 ~]# cd /opt/src/

[root@test-nodes1 src]# wget https://github.com/coreos/flannel/releases/download/v0.11.0/flannel-v0.11.0-linux-amd64.tar.gz

[root@test-nodes1 src]# mkdir /opt/flannel-v0.11.0

[root@test-nodes1 src]# tar xf flannel-v0.11.0-linux-amd64.tar.gz -C /opt/flannel-v0.11.0/

[root@test-nodes1 src]# ln -s /opt/flannel-v0.11.0/ /opt/flannel

[root@test-nodes1 src]# cd /opt/flannel

[root@test-nodes1 flannel]# mkdir cert

[root@test-nodes1 flannel]# cd cert/

[root@test-nodes1 cert]# scp test-operator:/opt/certs/ca.pem .

root@test-operator‘s password:

ca.pem 100% 1346 173.2KB/s 00:00

[root@test-nodes1 cert]# scp test-operator:/opt/certs/client.pem .

root@test-operator‘s password:

client.pem 100% 1363 207.0KB/s 00:00

[root@test-nodes1 cert]# scp test-operator:/opt/certs/client-key.pem .

root@test-operator‘s password:

client-key.pem

[root@test-nodes1 cert]# cd ..

flannel]# vi subnet.env

FLANNEL_NETWORK=172.7.0.0/16

FLANNEL_SUBNET=172.7.21.1/24 #每个nodes的子网不一样需修改，test-nodes1为21，而test-nodes2为22

FLANNEL_MTU=1500

FLANNEL_IPMASQ=false

flannel]# vi flanneld.sh

#!/bin/sh

./flanneld --public-ip=10.3.153.221 \ #另外一台test-nodes2需要修改

--etcd-endpoints=https://10.3.153.212:2379,https://10.3.153.221:2379,https://10.3.153.222:2379 --etcd-keyfile=./cert/client-key.pem --etcd-certfile=./cert/client.pem --etcd-cafile=./cert/ca.pem --iface=ens33 --subnet-file=./subnet.env --healthz-port=2401

[root@test-nodes1 flannel]# cd /opt/etcd

# 下面这一步在一步机器上执行即可，只需执行一次

[root@test-nodes1 etcd]# ./etcdctl set /coreos.com/network/config ‘{"Network": "172.7.0.0/16", "Backend": {"Type": "host-gw"}}‘

{"Network": "172.7.0.0/16", "Backend": {"Type": "host-gw"}}

[root@test-nodes1 etcd]# vi /etc/supervisord.d/flannel.ini

[program:flanneld-7-21]

command=/opt/flannel/flanneld.sh ; the program (relative uses PATH, can take args)

numprocs=1 ; number of processes copies to start (def 1)

directory=/opt/flannel ; directory to cwd to before exec (def no cwd)

autostart=true ; start at supervisord start (default: true)

autorestart=true ; retstart at unexpected quit (default: true)

startsecs=30 ; number of secs prog must stay running (def. 1)

startretries=3 ; max # of serial start failures (default 3)

exitcodes=0,2 ; ‘expected‘ exit codes for process (default 0,2)

stopsignal=QUIT ; signal used to kill process (default TERM)

stopwaitsecs=10 ; max num secs to wait b4 SIGKILL (default 10)

user=root ; setuid to this UNIX account to run the program

redirect_stderr=true ; redirect proc stderr to stdout (default false)

stdout_logfile=/data/logs/flanneld/flanneld.stdout.log ; stderr log path, NONE for none; default AUTO

stdout_logfile_maxbytes=64MB ; max # logfile bytes b4 rotation (default 50MB)

stdout_logfile_backups=4 ; # of stdout logfile backups (default 10)

stdout_capture_maxbytes=1MB ; number of bytes in ‘capturemode‘ (default 0)

stdout_events_enabled=false ; emit events on stdout writes (default false)

[root@test-nodes1 etcd]# supervisorctl update

flanneld-7-21: added process group

[root@test-nodes1 flannel]# supervisorctl status

etcd-server-7-21 RUNNING pid 14828, uptime 2 days, 14:55:02

flanneld-7-21 RUNNING pid 26991, uptime 0:00:48

kube-apiserver-7-21 RUNNING pid 14810, uptime 2 days, 14:56:17

kube-controller-manager-7-21 RUNNING pid 14868, uptime 2 days, 14:46:46

kube-kubelet-7-21 RUNNING pid 15095, uptime 2 days, 13:46:15

kube-proxy-7-21 RUNNING pid 22013, uptime 2 days, 13:05:18

kube-scheduler-7-21 RUNNING pid 25120, uptime 2 days, 12:53:29

三、flannel 工作原理

1、host-gw模型，两台运算节点在同一个网段，当flannel启动时会为两台运算节点增加相应的路由表，此时两台运算节点的POD就能互相通信，而flannel退出也不会影响，因为路由表已添加到宿主机。

2、VxLAN模型，两台运算节点在不同的网段