本文档讲解使用 keepalived 和 haproxy 实现 kube-apiserver 高可用的步骤:
- keepalived 提供 kube-apiserver 对外服务的 VIP;
- haproxy 监听 VIP,后端连接所有 kube-apiserver 实例,提供健康检查和负载均衡功能;
运行 keepalived 和 haproxy 的节点称为 LB 节点。由于 keepalived 是一主多备运行模式,故至少两个 LB 节点。
本文档复用 master 节点的三台机器,haproxy 监听的端口(8443) 需要与 kube-apiserver 的端口 6443 不同,避免冲突。
keepalived 在运行过程中周期检查本机的 haproxy 进程状态,如果检测到 haproxy 进程异常,则触发重新选主的过程,VIP 将飘移到新选出来的主节点,从而实现 VIP 的高可用。
所有组件(如 kubeclt、apiserver、controller-manager、scheduler 等)都通过 VIP 和 haproxy 监听的 8443 端口访问 kube-apiserver 服务。
安装软件包
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh root@${node_ip} "yum install -y keepalived haproxy"
done
配置和下发 haproxy 配置文件
haproxy 配置文件:
cat > haproxy.cfg <<EOF
global
log /dev/log local0
log /dev/log local1 notice
chroot /var/lib/haproxy
stats socket /var/run/haproxy-admin.sock mode 660 level admin
stats timeout 30s
user haproxy
group haproxy
daemon
nbproc 1
defaults
log global
timeout connect 5000
timeout client 10m
timeout server 10m
listen admin_stats
bind 0.0.0.0:10080
mode http
log 127.0.0.1 local0 err
stats refresh 30s
stats uri /status
stats realm welcome login Haproxy
stats auth admin:123456
stats hide-version
stats admin if TRUE
listen kube-master
bind 0.0.0.0:8443
mode tcp
option tcplog
balance source
server 172.27.129.105 172.27.129.105:6443 check inter 2000 fall 2 rise 2 weight 1
server 172.27.129.111 172.27.129.111:6443 check inter 2000 fall 2 rise 2 weight 1
server 172.27.129.112 172.27.129.112:6443 check inter 2000 fall 2 rise 2 weight 1
EOF
- haproxy 在 10080 端口输出 status 信息;
- haproxy 监听所有接口的 8443 端口,该端口与环境变量 ${KUBE_APISERVER} 指定的端口必须一致;
- server 字段列出所有 kube-apiserver 监听的 IP 和端口;
下发 haproxy.cfg 到所有 master 节点:
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
scp haproxy.cfg root@${node_ip}:/etc/haproxy
done
起 haproxy 服务
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh root@${node_ip} "systemctl restart haproxy"
done
检查 haproxy 服务状态
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh root@${node_ip} "systemctl status haproxy|grep Active"
done
确保状态为 active (running)
,否则查看日志,确认原因:
journalctl -u haproxy
检查 haproxy 是否监听 8443 端口:
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh root@${node_ip} "netstat -lnpt|grep haproxy"
done
确保输出类似于:
tcp 0 0 0.0.0.0:8443 0.0.0.0:* LISTEN 120583/haproxy
配置和下发 keepalived 配置文件
keepalived 是一主(master)多备(backup)运行模式,故有两种类型的配置文件。master 配置文件只有一份,backup 配置文件视节点数目而定,对于本文档而言,规划如下:
- master: 172.27.129.105
- backup:172.27.129.111、172.27.129.112
master 配置文件:
source /opt/k8s/bin/environment.sh
cat > keepalived-master.conf <<EOF
global_defs {
router_id lb-master-105
}
vrrp_script check-haproxy {
script "killall -0 haproxy"
interval 5
weight -30
}
vrrp_instance VI-kube-master {
state MASTER
priority 120
dont_track_primary
interface ${VIP_IF}
virtual_router_id 68
advert_int 3
track_script {
check-haproxy
}
virtual_ipaddress {
${MASTER_VIP}
}
}
EOF
- VIP 所在的接口(interface ${VIP_IF})为
eth0
; - 使用
killall -0 haproxy
命令检查所在节点的 haproxy 进程是否正常。如果异常则将权重减少(-30),从而触发重新选主过程; - router_id、virtual_router_id 用于标识属于该 HA 的 keepalived 实例,如果有多套 keepalived HA,则必须各不相同;
backup 配置文件:
source /opt/k8s/bin/environment.sh
cat > keepalived-backup.conf <<EOF
global_defs {
router_id lb-backup-105
}
vrrp_script check-haproxy {
script "killall -0 haproxy"
interval 5
weight -30
}
vrrp_instance VI-kube-master {
state BACKUP
priority 110
dont_track_primary
interface ${VIP_IF}
virtual_router_id 68
advert_int 3
track_script {
check-haproxy
}
virtual_ipaddress {
${MASTER_VIP}
}
}
EOF
- VIP 所在的接口(interface ${VIP_IF})为
eth0
; - 使用
killall -0 haproxy
命令检查所在节点的 haproxy 进程是否正常。如果异常则将权重减少(-30),从而触发重新选主过程; - router_id、virtual_router_id 用于标识属于该 HA 的 keepalived 实例,如果有多套 keepalived HA,则必须各不相同;
- priority 的值必须小于 master 的值;
下发 keepalived 配置文件
下发 master 配置文件:
scp keepalived-master.conf root@172.27.129.105:/etc/keepalived/keepalived.conf
下发 backup 配置文件:
scp keepalived-backup.conf root@172.27.129.111:/etc/keepalived/keepalived.conf
scp keepalived-backup.conf root@172.27.129.112:/etc/keepalived/keepalived.conf
起 keepalived 服务
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh root@${node_ip} "systemctl restart keepalived"
done
检查 keepalived 服务
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh root@${node_ip} "systemctl status keepalived|grep Active"
done
确保状态为 active (running)
,否则查看日志,确认原因:
journalctl -u keepalived
查看 VIP 所在的节点,确保可以 ping 通 VIP:
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh ${node_ip} "/usr/sbin/ip addr show ${VIP_IF}"
ssh ${node_ip} "ping -c 1 ${MASTER_VIP}"
done
查看 haproxy 状态页面
浏览器访问 ${MASTER_VIP}:10080/status 地址,查看 haproxy 状态页面: