kubernetes-CNI网络插件

flannel-github下载链接
CNI网络插件的主要功能就是为了实现pod资源能够跨宿主机进行通信
要在每个pod节点上安装

壹，在243上

壹-壹：上传、解压、拉取证书

cd /opt/src/
上传软件
mkdir /opt/flannel-v0.11.1
tar -zxvf flannel-v0.11.0-linux-amd64.tar.gz -C /opt/flannel-v0.11.0/
ln -s /opt/flannel-v0.11.0/ /opt/flannel
mkdir /opt/flannel/cert/
cd /opt/flannel/cert/
scp 192.168.6.245:/opt/certs/ca.pem /opt/flannel/cert/
scp 192.168.6.245:/opt/certs/client.pem /opt/flannel/cert/
scp 192.168.6.245:/opt/certs/client-key.pem /opt/flannel/cert/

壹-贰 编辑flannel配置文件

cd /opt/flannel/
vi subnet.env
FLANNEL_NETWORK=172.6.0.0/16
FLANNEL_SUBNET=172.6.243.1/24
FLANNEL_MTU=1500
FLANNEL_IPMASQ=false

壹-叁 创建启动脚本

1-1，vi flanneld.sh

#!/bin/sh
./flanneld \
  --public-ip=192.168.6.243 \
  --etcd-endpoints=https://192.168.6.242:2379,https://192.168.6.243:2379,https://192.168.6.244:2379 \
  --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

1-2 , 检查配置，权限，创建日志目录
chmod +x /opt/flannel/flanneld.sh
mkdir -p /data/logs/flanneld
1-3， 创建supervisor配置文件
vim /etc/supervisord.d/flannel.ini

[program:flanneld-6-243]
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)
killasgroup=true                                             ; kill all process in a group
stopasgroup=true                                             ; stop all process in a group
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)
killasgroup=true
stopasgroup=true

壹-肆 ，操作etcd,增加host-gw # 只需执行一次即可

cd /opt/etcd
./etcdctl set /coreos.com/network/config ‘{“Network”: “172.6.0.0/16”, “Backend”: {“Type”: “host-gw”}}’ #在etcd中设置 host-gw模式
./etcdctl get /coreos.com/network/config #检查是否配置成功
./etcdctl rm /coreos.com/network/config ‘{“Network”: “172.6.0.0/16”, “Backend”: {“Type”: “host-gw”}}’ ####### 删除设置
启动flannel
supervisorctl update
supervisorctl status
检查route -n 网关设置

贰，在244上

贰-壹 ，上传软件、解压、拉取证书

上传软件到/opt/src
mkdir /opt/flannel-v0.11.1

tar -zxvf flannel-v0.11.0-linux-amd64.tar.gz -C /opt/flannel-v0.11.1/
ln -s /opt/flannel-v0.11.1/ /opt/flannel

cd /opt/flannel
mkdir cert
scp 192.168.6.245:/opt/certs/ca.pem /opt/flannel/cert/
scp 192.168.6.245:/opt/certs/client.pem /opt/flannel/cert/
scp 192.168.6.245:/opt/certs/client-key.pem /opt/flannel/cert/

贰 -贰 ，编辑flannel配置文件

vi subnet.env
FLANNEL_NETWORK=172.6.0.0/16
FLANNEL_SUBNET=172.6.244.1/24
FLANNEL_MTU=1500
FLANNEL_IPMASQ=false

贰-叁 ，创建启动脚本：

vi flanneld.sh

#!/bin/sh
./flanneld \
  --public-ip=192.168.6.244 \
  --etcd-endpoints=https://192.168.6.242:2379,https://192.168.6.243:2379,https://192.168.6.244:2379 \
  --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

启动文件
vi /etc/supervisord.d/flannel.ini

[program:flanneld-6-244]
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)
killasgroup=true                                             ; kill all process in a group
stopasgroup=true                                             ; stop all process in a group
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)
killasgroup=true
stopasgroup=true

mkdir /data/logs/flanneld
chmod +x /opt/flannel/flanneld.sh
supervisorctl update
supervisorctl status

在没有加flannel前，宿主机只能ping的通本机上运行的pod,无法访问其他宿主机上运行的pods

在添加了flannel之后，可以实现宿主机跨node节点与pod互通

还可实现同一个资源控制下的pods互通

叁：关于flannel 典型的网络模型待续

叁-壹，flannel的host-gw网络模型

这种模型相当于在各运行的node节点上添加了一条路由

flannel的作用相当于：添加路由
添加路由
route add -net 172.6.243.0/24 gw 192.168.6.243
route add -net 172.6.244.0/24 gw 192.168.6.244
删除路由
route del -net 172.6.243.0/24 gw 192.168.6.243
route del -net 172.6.244.0/24 gw 192.168.6.244

叁-贰：Vxlan 模型

肆：各个节点上优化iptables规则

1，优化pod之间互访不用原地址

1. 在没有优化之前通过运行在244上的pods去curl
   运行在243上的pod时，243上运行的pods的日志显示，访问地址是自己宿主机（243）的ip地址，显然不行，应该是谁访问的留下谁的地址（pod访问的应该留下pod的地址）。故而才会优化各节点，实现pod访问的应该显示pod的地址

2，涉及到的验证测试命令：

登录进一个运行中的pod
kubectl exec -it nginx-dp-5cb55d45c8-ps9rw -n kube-public /bin/sh #进入一个pod中
然后在pod中去curl另一个pod, 于此同时去监听被curl pod的实时日志
kubectl logs -f nginx-dp-5cb55d45c8-gl2xj -n kube-public
以nginx为例

3，在所有需要优化的机器上安装iptables

yum -y install iptables-services
systemctl start iptables
systemcl enable iptables
systemctl status iptables

4，查看k8s预设的iptables 规则

iptables-save|grep -i postrouting

5，删除预设置的iptables规则

iptables -t nat -D POSTROUTING -s 172.6.243.0/24 ! -o docker0 -j MASQUERADE

6，然后添加一条经过修改过的规则

iptables -t nat -I POSTROUTING -s 172.6.243.0/24 ! -d 172.6.0.0/16 ! -o docker0 -j MASQUERADE

192.168.6.243主机上的，来源是172.6.243.0/24段的docker的ip，目标ip不是172.6.0.0/16段，网络发包不从docker0桥设备出站的，才进行转换
yum install iptables-services -y
systemctl start iptables.service
systemctl start iptables.service

7，把默认禁止的规则删除掉

1，查找默认规则
iptables-save | grep -i reject
2，删除默认的规则
iptables -t filter -D INPUT -j REJECT --reject-with icmp-host-prohibited
iptables -t filter -D FORWARD -j REJECT --reject-with icmp-host-prohibited
3，保存修改的配置
iptables-save > /etc/sysconfig/iptables
service iptables save

每个节点上都需要执行
最终的结果如下：