第三篇（二进制部署k8s集群---Flannel网络和keepalived+haproxy高可用）

Posted 2020-12-21

此文将搭建flannel网络，目的使跨主机的docker能够互相通信，也是保障kubernetes集群的网络基础和保障，和ha高可用。
部署的服务器为：
master1 192.168.206.31
master2 192.168.206.32
master3 192.168.206.33
node1 192.168.206.41
node2 192.168.206.42
node3 192.168.206.43
VIP：192.168.206.30
ha1 192.168.206.36
ha2 192.168.206.37

一、生成Flannel网络TLS证书

在所有集群节点都安装Flannel，下面的操作在k8s-master1上进行。
1、创建证书签名请求

cat > flanneld-csr.json <<EOF
{
  "CN": "flanneld",
  "hosts": [],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "Zhejiang",
      "L": "hangzhou",
      "O": "k8s",
      "OU": "System"
    }
  ]
}
EOF

该证书只会被 kubectl 当做 client 证书使用，所以 hosts 字段为空；

2、生成证书和私钥：

cfssl gencert -ca=/data/ssl/ca.pem   -ca-key=/data/ssl/ca-key.pem   -config=/data/ssl/ca-config.json   -profile=kubernetes flanneld-csr.json | cfssljson -bare flanneld

创建证书存放目录：
 mkdir /opt/kubernetes/ssl/flannel

这里是复制到3master+3node上
cp flanneld*.pem /opt/kubernetes/ssl/flannel

二、部署 Flannel
1、下载安装Flannel

wget https://github.com/coreos/flannel/releases/download/v0.10.0/flannel-v0.10.0-linux-amd64.tar.gz
tar -xzvf flannel-v0.10.0-linux-amd64.tar.gz
cp {flanneld,mk-docker-opts.sh} /opt/kubernetes/bin/

2、向 etcd 写入网段信息
下面2条命令在etcd集群中任意一台执行一次即可，也是是创建一个flannel网段供docker分配使用

etcdctl --ca-file=/opt/kubernetes/ssl/etcd/ca.pem --cert-file=/opt/kubernetes/ssl/etcd/etcd.pem --key-file=/opt/kubernetes/ssl/etcd/etcd-key.pem mkdir /opt/kubernetes/network
etcdctl --ca-file=/opt/kubernetes/ssl/etcd/ca.pem --cert-file=/opt/kubernetes/ssl/etcd/etcd.pem --key-file=/opt/kubernetes/ssl/etcd/etcd-key.pem mk /opt/kubernetes/network/config ‘{"Network":"172.30.0.0/16","SubnetLen":24,"Backend":{"Type":"vxlan"}}‘

3、创建system unit文件

cat > /etc/systemd/system/flanneld.service << EOF
[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
ExecStart=/opt/kubernetes/bin/flanneld   -etcd-cafile=/opt/kubernetes/ssl/flannel/ca.pem   -etcd-certfile=/opt/kubernetes/ssl/flannel/flanneld.pem   -etcd-keyfile=/opt/kubernetes/ssl/flannel/flanneld-key.pem   -etcd-endpoints=https://192.168.206.31:2379,https://192.168.206.32:2379,https://192.168.206.33:2379   -etcd-prefix=/opt/kubernetes/network
ExecStartPost=/opt/kubernetes/bin/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/docker
Restart=on-failure

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

mk-docker-opts.sh 脚本将分配给 flanneld 的 Pod 子网网段信息写入到 /run/flannel/docker 文件中，后续 docker 启动时使用这个文件中参数值设置 docker0 网桥。
flanneld 使用系统缺省路由所在的接口和其它节点通信，对于有多个网络接口的机器（如，内网和公网），可以用 -iface=enpxx 选项值指定通信接口。

4、启动flannel并且设置开机自启动

systemctl daemon-reload
systemctl enable flanneld
systemctl start flanneld

5、查看flannel分配的子网信息

[root@k8s-master1 ~]# cat /run/flannel/docker 
DOCKER_OPT_BIP="--bip=172.30.94.1/24"
DOCKER_OPT_IPMASQ="--ip-masq=true"
DOCKER_OPT_MTU="--mtu=1450"
DOCKER_NETWORK_OPTIONS=" --bip=172.30.94.1/24 --ip-masq=true --mtu=1450"

[root@k8s-master1 ~]# cat /run/flannel/subnet.env 
FLANNEL_NETWORK=172.30.0.0/16
FLANNEL_SUBNET=172.30.94.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=false

/run/flannel/docker是flannel分配给docker的子网信息，/run/flannel/subnet.env包含了flannel整个大网段以及在此节点上的子网段。

6、查看flannel网络是否生效

Last login: Thu Nov 19 09:28:40 2020 from 192.168.206.1
[root@k8s-master1 ~]# ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:6e:7f:49 brd ff:ff:ff:ff:ff:ff
    inet 192.168.206.31/24 brd 192.168.206.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::bbd4:6d75:22b1:e631/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
    inet6 fe80::129b:129d:71ca:5d94/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
    inet6 fe80::1b37:c32:6cc4:be75/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
3: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default 
    link/ether de:b1:04:6f:d6:57 brd ff:ff:ff:ff:ff:ff
    inet 172.30.65.0/32 brd 172.30.65.0 scope global flannel.1
       valid_lft forever preferred_lft forever

三、安装docker、配置docker支持flannel网络
1、所有node安装docker

yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

#安装指定版本，这里安装18.06
yum list docker-ce --showduplicates | sort -r
yum install -y docker-ce-18.06.1.ce-3.el7

systemctl start docker && systemctl enable docker

2、配置docker支持flannel网络，所有docker节点都操作

[root@k8s-master1 ~]# vi /etc/systemd/system/multi-user.target.wants/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target firewalld.service
Wants=network-online.target

[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
EnvironmentFile=/run/flannel/docker
ExecStart=/usr/bin/dockerd $DOCKER_NETWORK_OPTIONS
ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
# restart the docker process if it exits prematurely
Restart=on-failure
StartLimitBurst=3
StartLimitInterval=60s

[Install]
WantedBy=multi-user.target

3、重启docker，使配置生效

systemctl daemon-reload
systemctl restart docker

4、查看所有集群主机的网络情况

etcdctl --ca-file=/opt/kubernetes/ssl/etcd/ca.pem --cert-file=/opt/kubernetes/ssl/etcd/etcd.pem --key-file=/opt/kubernetes/ssl/etcd/etcd-key.pem ls /opt/kubernetes/network/subnets

四、keepalived+haproxy高可用部署。
部署服务器
ha1 192.168.206.36
ha2 192.168.206.37
1、所有haproxy安装haproxy

yum install -y haproxy

cat <<EOF > /etc/haproxy/haproxy.cfg
global
    log         127.0.0.1 local2

    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user        haproxy
    group       haproxy
    daemon
defaults
    mode                    tcp
    log                     global
    retries                 3
    timeout connect         10s
    timeout client          1m
    timeout server          1m
frontend  k8s-api
    bind        *:6443
    bind        *:443
    mode        tcp
    option      tcplog
    default_backend k8s-api
backend k8s-api
    mode        tcp
    option      tcplog
    option      tcp-check
    balance     roundrobin
    default-server inter 10s downinter 5s rise 2 fall 2 slowstart 60s maxconn 250 maxqueue 256 weight 100
    server master1 192.168.206.31:6443 check
    server master2 192.168.206.32:6443 check
    server master3 192.168.206.33:6443 check
EOF

2、启动所有haproxy

systemctl start haproxy
systemctl status haproxy
systemctl enable haproxy

3、所有haproxy安装keepalived

yum install -y keepalived

cat <<EOF > /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   router_id LVS_K8S
}

vrrp_instance VI_1 {
    state MASTER(BACKUP)
    interface ens33
    virtual_router_id 51
    priority 100(备50)
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        VIP/24
    }
}
EOF

4、所有haproxy启动keepalived

systemctl restart keepalived
systemctl status keepalived
systemctl enable keepalived

启动完成可用查看vip，或关闭主ha看vip是否偏移。