本文將在前文基礎上介紹k8s集群的高可用實踐，一般來講，k8s集群高可用主要包含以下幾個內容：
1、etcd集群高可用
2、集群dns服務高可用
3、kube-apiserver、kube-controller-manager、kube-scheduler等master組件的高可用

其中etcd實現的辦法較為容易，具體實現辦法可參考前文：
https://blog.51cto.com/ylw6006/2095871

集群dns服務高可用，可以通過配置dns的pod副本數為2，通過配置label實現2個副本運行在在不同的節點上實現高可用。

kube-apiserver服務的高可用，可行的方案較多，具體介紹可參考文檔：
https://jishu.io/kubernetes/kubernetes-master-ha/

kube-controller-manager、kube-scheduler等master組件的高可用相對容易實現，運行多份實例即可。

一、環境介紹

master節點1： 192.168.115.5/24 主機名：vm1 
master節點2： 192.168.115.6/24 主機名：vm2
VIP地址： 192.168.115.4/24 (使用keepalived實現)
Node節點1: 192.168.115.6/24 主機名：vm2
Node節點2: 192.168.115.7/24 主機名：vm3

操作系統版本：centos 7.2 64bit
K8s版本：1.9.6 二進制部署

本文演示環境是在前文的基礎上，已有k8s集群（1個master節點、2個node節點上），實現k8s集群master組件的高可用，關於k8s環境的部署請參考前文鏈接!
1、配置Etcd集群和TLS認證 ——> https://blog.51cto.com/ylw6006/2095871
2、Flannel網絡組件部署 ——> https://blog.51cto.com/ylw6006/2097303
3、升級Docker服務 ——> https://blog.51cto.com/ylw6006/2103064
4、K8S二進制部署Master節點 ——> https://blog.51cto.com/ylw6006/2104031
5、K8S二進制部署Node節點 ——> https://blog.51cto.com/ylw6006/2104692

二、證書更新

在vm1節點上完成證書的更新，重點是要把master相關ip全部全部加入到列表里面

# mkdir api-ha && cd api-ha # cat k8s-csr.json { "CN": "kubernetes", "hosts": [ "127.0.0.1", "192.168.115.4", "192.168.115.5", "192.168.115.6", "10.254.0.1", "kubernetes", "kubernetes.default", "kubernetes.default.svc", "kubernetes.default.svc.cluster", "kubernetes.default.svc.cluster.local" ], "key": { "algo": "rsa", "size": 2048 }, "names": [ { "C": "CN", "ST": "FuZhou", "L": "FuZhou", "O": "k8s", "OU": "System" } ] } # cfssl gencert -ca=/etc/ssl/etcd/ca.pem \ -ca-key=/etc/ssl/etcd/ca-key.pem \ -config=/etc/ssl/etcd/ca-config.json \ -profile=kubernetes k8s-csr.json | cfssljson -bare kubernetes # mv *.pem /etc/kubernetes/ssl/

三、配置master組件

1、復制vm1的kube-apiserver、kube-controller-manager、kube-scheduler文件到vm2節點上

# cd /usr/local/sbin # scp -rp kube-apiserver kube-controller-manager kube-scheduler vm2:/usr/local/sbin/

2、復制vm1的證書文件到vm2節點上

# cd /etc/kubernetes/ssl # scp -rp ./* vm2:/etc/kubernetes/ssl

3、配置服務並啟動服務

# cat /usr/lib/systemd/system/kube-apiserver.service [Unit] Description=Kubernetes API Server Documentation=https://github.com/GoogleCloudPlatform/kubernetes After=network.target [Service] ExecStart=/usr/local/sbin/kube-apiserver \ --admission-control=NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,ResourceQuota \ --advertise-address=0.0.0.0 \ --bind-address=0.0.0.0 \ --insecure-bind-address=127.0.0.1 \ --authorization-mode=RBAC \ --runtime-config=rbac.authorization.k8s.io/v1alpha1 \ --kubelet-https=true \ --enable-bootstrap-token-auth=true \ --token-auth-file=/etc/kubernetes/token.csv \ --service-cluster-ip-range=10.254.0.0/16 \ --service-node-port-range=1024-65535 \ --tls-cert-file=/etc/kubernetes/ssl/kubernetes.pem \ --tls-private-key-file=/etc/kubernetes/ssl/kubernetes-key.pem \ --client-ca-file=/etc/ssl/etcd/ca.pem \ --service-account-key-file=/etc/ssl/etcd/ca-key.pem \ --etcd-cafile=/etc/ssl/etcd/ca.pem \ --etcd-certfile=/etc/ssl/etcd/server.pem \ --etcd-keyfile=/etc/ssl/etcd/server-key.pem \ --etcd-servers=https://192.168.115.5:2379,https://192.168.115.6:2379,https://192.168.115.7:2379 \ --enable-swagger-ui=true \ --allow-privileged=true \ --apiserver-count=3 \ --audit-log-maxage=30 \ --audit-log-maxbackup=3 \ --audit-log-maxsize=100 \ --audit-log-path=/var/lib/audit.log \ --event-ttl=1h \ --v=2 Restart=on-failure RestartSec=5 Type=notify LimitNOFILE=65536 [Install] WantedBy=multi-user.target
# cat /usr/lib/systemd/system/kube-scheduler.service [Unit] Description=Kubernetes Scheduler Documentation=https://github.com/GoogleCloudPlatform/kubernetes [Service] ExecStart=/usr/local/sbin/kube-scheduler \ --address=127.0.0.1 \ --master=http://127.0.0.1:8080 \ --leader-elect=true \ --v=2 Restart=on-failure RestartSec=5 [Install] WantedBy=multi-user.target
# cat /usr/lib/systemd/system/kube-controller-manager.service [Unit] Description=Kubernetes Controller Manager Documentation=https://github.com/GoogleCloudPlatform/kubernetes [Service] ExecStart=/usr/local/sbin/kube-controller-manager \ --address=127.0.0.1 \ --master=http://127.0.0.1:8080 \ --allocate-node-cidrs=true \ --service-cluster-ip-range=10.254.0.0/16 \ --cluster-cidr=172.30.0.0/16 \ --cluster-name=kubernetes \ --cluster-signing-cert-file=/etc/ssl/etcd/ca.pem \ --cluster-signing-key-file=/etc/ssl/etcd/ca-key.pem \ --service-account-private-key-file=/etc/ssl/etcd/ca-key.pem \ --root-ca-file=/etc/ssl/etcd/ca.pem \ --leader-elect=true \ --v=2 Restart=on-failure RestartSec=5 [Install] WantedBy=multi-user.target
# systemctl enable kube-apiserver # systemctl enable kube-controller-manager # systemctl enable kube-scheduler # systemctl start kube-apiserver # systemctl start kube-controller-manager # systemctl start kube-scheduler

注意：

vm1上的api-server配置文件需要將--advertise-address、--bind-address兩個參數修改為全網監聽

四、安裝和配置keepalived

# yum -y install keepalived # cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { ylw@fjhb.cn } notification_email_from admin@fjhb.cn smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_MASTER } vrrp_script check_apiserver { script "/etc/keepalived/check_apiserver.sh" interval 3 } vrrp_instance VI_1 { state MASTER interface ens33 virtual_router_id 60 priority 100 advert_int 1 authentication { auth_type PASS auth_pass k8s.59iedu.com } virtual_ipaddress { 192.168.115.4/24 } track_script { check_apiserver } }
# cat /usr/lib/systemd/system/keepalived.service [Unit] Description=LVS and VRRP High Availability Monitor After=syslog.target network-online.target kube-apiserver.service Require=kube-apiserver.service  [Service] Type=forking PIDFile=/var/run/keepalived.pid KillMode=process EnvironmentFile=-/etc/sysconfig/keepalived ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS ExecReload=/bin/kill -HUP $MAINPID  [Install] WantedBy=multi-user.target

注意:

vm2節點上需要修改state為BACKUP, priority為99 （priority值必須小於master節點配置值）

# cat /etc/keepalived/check_apiserver.sh #!/bin/bash flag=$(systemctl status kube-apiserver &> /dev/null;echo $?) if [[ $flag != 0 ]];then echo "kube-apiserver is down,close the keepalived" systemctl stop keepalived fi # chmod +x /etc/keepalived/check_apiserver.sh # systemctl daemon-reload # systemctl enable keepalived # systemctl start keepalived

五、修改客戶端配置

1、Kubelet.kubeconfig 、bootstrap.kubeconfig、kube-proxy.kubeconfig 配置

# grep 'server' /etc/kubernetes/kubelet.kubeconfig server: https://192.168.115.4:6443 # grep 'server' /etc/kubernetes/bootstrap.kubeconfig server: https://192.168.115.4:6443 # grep 'server' /etc/kubernetes/kube-proxy.kubeconfig server: https://192.168.115.4:6443

2、confing配置

# grep 'server' /root/.kube/config server: https://192.168.115.4:6443

3、重啟客戶端服務

# systemctl restart kubelet # systemctl restart kube-proxy

六、測試

1、關閉服務前的集群狀態，VIP在vm1節點上
K8S集群Master高可用實踐

K8S集群Master高可用實踐

2、在vm1上將kube-apiserver服務停止，可以看到VIP消息，但任何可以連接master獲取pod信息
K8S集群Master高可用實踐
日志顯示vip被自動移除
K8S集群Master高可用實踐
3、在vm2上能看到自動注冊上了VIP，且kubectl客戶端連接正常
K8S集群Master高可用實踐
K8S集群Master高可用實踐
4、在vm1上將kube-apiserver、keepalived服務啟動，由於配置的是主從模式，所以會搶占VIP
K8S集群Master高可用實踐
5、在vm2上可以看到VIP的釋放，keepalived重新進入backup狀態
K8S集群Master高可用實踐
6、在整個過程中可以用其他的客戶端來連接master VIP來測試服務器的連續性
K8S集群Master高可用實踐

七、使用haproxy改進

只用keepalived實現master ha，當api-server的訪問量大的時候，會有性能瓶頸問題，通過配置haproxy，可以同時實現master的ha和流量的負載均衡。
1、安裝和配置haproxy，兩台master做同樣的配置

# yum -y install haproxy # cat /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 stats socket /var/lib/haproxy/stats defaults mode tcp log global option tcplog option dontlognull option redispatch retries 3 timeout queue 1m timeout connect 10s timeout client 1m timeout server 1m timeout check 10s maxconn 3000 listen stats mode http bind :10086 stats enable stats uri /admin?stats stats auth admin:admin stats admin if TRUE frontend k8s_https *:8443 mode tcp maxconn 2000 default_backend https_sri backend https_sri balance roundrobin server s1 192.168.115.5:6443 check inter 10000 fall 2 rise 2 weight 1 server s2 192.168.115.6:6443 check inter 10000 fall 2 rise 2 weight 1

2、修改kube-apiserver配置,ip地址根據實際情況修改

# grep 'address' /usr/lib/systemd/system/kube-apiserver.service --advertise-address=192.168.115.5 \ --bind-address=192.168.115.5 \ --insecure-bind-address=127.0.0.1 \

3、修改keepalived啟動腳本和配置文件,vrrp腳本的ip地址根據實際情況修改

# cat /usr/lib/systemd/system/keepalived.service [Unit] Description=LVS and VRRP High Availability Monitor After=syslog.target network-online.target Require=haproxy.service ########以下輸出省略#########
# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { ylw@fjhb.cn } notification_email_from admin@fjhb.cn smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_MASTER } vrrp_script check_apiserver { script "curl -o /dev/null -s -w %{http_code} -k https://192.168.115.5:6443" interval 3 timeout 3 fall 2 rise 2 } ########以下輸出省略#########

4、修改kubelet和kubectl客戶端配置文件，指向haproxy的端口8443

# grep '192' /etc/kubernetes/bootstrap.kubeconfig server: https://192.168.115.4:8443 # grep '192' /etc/kubernetes/kubelet.kubeconfig server: https://192.168.115.4:8443 # grep '192' /etc/kubernetes/kube-proxy.kubeconfig server: https://192.168.115.4:8443 # grep '192' /root/.kube/config server: https://192.168.115.4:8443

5、重啟服務驗證
master

# systemctl daemon-reload # systemctl enable haproxy # systemctl start haproxy # systemctl restart keepalived # systemctl restart kube-apiserver

kubelet

# systemctl restart kubelet # systemctl restart kube-proxy

K8S集群Master高可用實踐
K8S集群Master高可用實踐