HA Cluster和keepalived主从,主主高可用设置以及varnish缓存机制（一）

一、简述HA cluster原理

高可用集群，英文原文为High Availability Cluster，简称HA Cluster；集群（cluster）就是一组计算机，它们作为一个整体向用户提供一组网络资源。这些单个的计算机系统就是集群的节点（node）。高可用性集群（HA cluster）是指如单系统一样地运行并支持（计算机）持续正常运行的一个主机群。

高可用集群的出现是为了使集群的整体服务尽可能可用，从而减少由计算机硬件和软件易错性所带来的损失。如果某个节点失效，它的备援节点将在几秒钟的时间内接管它的职责。因此，对于用户而言，集群永远不会停机。高可用集群软件的主要作用就是实现故障检查和业务切换的自动化。

简单的说高可用集群就是为了解决集群中的单点故障（SPoF），保证服务不间断运行的冗余（redundant）手段。

SPoF：Single Point of Failure；单点故障
冗余（redundant）：在两个节点上装一个软件程序，根据判断状态完成资源转移；

高可用集群的衡量标准

通常用平均无故障时间（MTTF）来度量系统的可靠性，用平均故障维修时间（MTTR）来度量系统的可维护性。于是可用性被定义为：HA=MTTF/(MTTF+MTTR)*100%

可用性衡量指标：
· 基本可用性：2个9；99%；年度停机时间87.6小时
· 较高可用性：3个9；99.9%；年度停机时间8.8小时
· 具有故障自动恢复能力的可用性：4个9；99.99%；年度停机时间53分钟
· 极高可用性：5个9；99.999%；年度停机时间5分钟

二、keepalived

KeepAlived主要有两个功能：

(1).能够对RealServer进行健康状况检查，支持4层、5层和7层协议进行健康检查；
(2).对负载均衡调度器实现高可用，防止Director单点故障。

KeepAlived工作过程：
keepalived实现故障转移的功能是通过VRRP（virtual router redundancy protocol虚拟路由器冗余协议）协议来实现的。在keepalived正常工作的时候，主节点（master）会不断的发送心跳信息给备节点（backup），当备节点不能在一定时间内收到主节点的心跳信息时，备节点会认为节点宕了，然后会接管主节点上的资源，并继续向外提供服务保证其可用性。当主节点恢复的时候，备节点会自动让出资源并再次自动成为备节点。
KeepAlived基于vrrp协议的软件实现，原生设计的目的为了高可用ipvs服务；

基于vrrp协议完成地址流动；
为vip地址所在的节点生成ipvs规则（在配置文件中预先定义）；
为ipvs集群的各RS做健康状态检测；
基于脚本调用接口通过执行脚本完成脚本中定义的功能，进而影响集群事务；

HA Cluser的配置前提：
(1) 各节点时间必须同步；ntp，chrony
(2) 确保iptales及selinux不会成为阻碍；
(3) 各节点之间可通过主机名互相通信（对KA并非必须）；
建议使用/etc/hosts文件实现；
(4) 确保各节点的用于集群服务的接口支持MULTICAST通信；
D类：224-239
Keepalived安装配置：
在CentOS6.4以后，keepalived随base仓库提供；

程序环境：
主配置文件：/etc/keepalived/keepalived.conf
主程序文件：/usr/sbin/keepalived
nit File：keepalived.service
Unit File的环境配置文件：/etc/sysconfig/keepalived
配置文件组件部分：
TOP HIERACHY
- GLOBAL CONFIGURATION
- Global definitions
- Static routes/addresses
- VRRPD CONFIGURATION
- VRRP synchronization group(s)：vrrp同步组；
- VRRP instance(s)：每个vrrp instance即一个vrrp路由器；
- LVS CONFIGURATION
- Virtual server group(s)
- Virtual server(s)：ipvs集群的vs和rs；

配置语法：

- 配置虚拟器：
vrrp_instance { ...... }
- 专用参数：
state MASTER|BACKUP： 当前节点在此虚拟路由器上的初始状态；只能有一个是MASTER，余下的都应该为BACKUP；
interface IFACE_NAME：绑定为当前虚拟路由器使用的物理接口；
virtual_router_id VRID：当前虚拟路由器的唯一标识，范围是0-255；
priority 100：当前主机在此虚拟路由器中的优先级；范围1-254；
advert_int 1：vrrp通告的时间间隔；

    authentication {
        auth_type AH|PASS
        auth_pass 
    }
    virtual_ipaddress {
        / brd  dev  scope  label 
        192.168.200.16/24 dev eth1
        192.168.200.17/24 dev eth2 label eth2:1
    }
    track_interface {
        eth0
        eth1
        ...
    }  
# 配置要监控的网络接口，一旦接口出现故障，则转为FAULT状态；
# nopreempt：定义工作模式为非抢占模式；
# preempt_delay 300：抢占模式下，节点上线后触发新选举操作的延迟时长；

定义通知脚本：

notify_master |：当前节点成为主节点时触发的脚本；
notify_backup |：当前节点转为备节点时触发的脚本；
notify_fault |：当前节点转为“失败”状态时触发的脚本；
notify |：通用格式的通知触发机制，一个脚本可完成以上三种状态的转换时的通知；

虚拟服务器：
配置参数：

virtual_server IP port |
virtual_server fwmark int 
{
    ...
    real_server {
        ...
    }
    ...
}

常用参数：
delay_loop ：服务轮询的时间间隔；
lb_algo rr|wrr|lc|wlc|lblc|sh|dh：定义调度方法；
lb_kind NAT|DR|TUN：集群的类型；
persistence_timeout ：持久连接时长；
protocol TCP：服务协议，仅支持TCP；
sorry_server ：备用服务器地址；

real_server  
{
    weight 
    notify_up |
    notify_down |
    HTTP_GET|SSL_GET|TCP_CHECK|SMTP_CHECK|MISC_CHECK { ... }：定义当前主机的健康状态检测方法；
                }

HTTP_GET|SSL_GET：应用层检测

HTTP_GET|SSL_GET {
    url {
        path ：定义要监控的URL；
        status_code ：判断上述检测机制为健康状态的响应码；
        digest ：判断上述检测机制为健康状态的响应的内容的校验码；
    }
    nb_get_retry ：重试次数；
    delay_before_retry ：重试之前的延迟时长；
    connect_ip ：向当前RS的哪个IP地址发起健康状态检测请求
    connect_port ：向当前RS的哪个PORT发起健康状态检测请求
    bindto ：发出健康状态检测请求时使用的源地址；
    bind_port ：发出健康状态检测请求时使用的源端口；
    connect_timeout ：连接请求的超时时长；
}

TCP_CHECK：传输层检测

TCP_CHECK {
    connect_ip ：向当前RS的哪个IP地址发起健康状态检测请求
    connect_port ：向当前RS的哪个PORT发起健康状态检测请求
    bindto ：发出健康状态检测请求时使用的源地址；
    bind_port ：发出健康状态检测请求时使用的源端口；
    connect_timeout ：连接请求的超时时长；
}

三、Keepalived实现主从、主主架构

主从配置：
准备2个节点：node1：192.168.80.136；node2：192.168.80.230
同步时间：[root@node1 ~]# ntpdate 192.168.80.1
安装配置keepalived：
在node1如下配置

[root@node1 ~]# yum install -y keepalived    #安装keepalived
[root@node1 ~]# cd /etc/keepalived/
[root@node1 keepalived]# cp keepalived.conf{,.bak}    #备份keepalived原始配置文件
[root@node1 keepalived]# vim keepalived.conf
# 在打开的文件中配置如下内容
! Configuration File for keepalived

global_defs {
   notification_email {
     root@localhost
   }
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node1
    vrrp_mcast_group4 224.1.105.33
}

vrrp_instance VI_1 {
    state MASTER    #当前节点在此虚拟路由器上的初始状态；只能有一个是MASTER，余下的都应该为BACKUP；
    interface eth33
    virtual_router_id 33
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.80.93 dev ens33 label ens33:0
    }
}

在node2节点上如下配置：

[root@node2 ~]# yum install -y keepalived    #安装keepalived
[root@node2 ~]# cd /etc/keepalived
[root@node2 keepalived]# cp keepalived.conf{,.bak}  #备份keepalived原始配置文件
[root@node2 keepalived]# vim keepalived.conf
# 在打开的文件中配置如下内容
! Configuration File for keepalived

global_defs {
   notification_email {
    root@localhost
   }
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node2
    vrrp_mcast_group4 224.1.105.33
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 33
    priority 96
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.80.93 dev ens33 label ens33:0
    }
}

启动node2节点keepalived测试

[root@node2 keepalived]# systemctl start keepalived
[root@node2 keepalived]# ifconfig
...
ens33:0: flags=4163  mtu 1500
        inet 192.168.80.93  netmask 255.255.255.255  broadcast 0.0.0.0
        ether 00:0c:29:40:ee:7c  txqueuelen 1000  (Ethernet)
...
[root@node2 keepalived]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-01-16 12:24:22 CST; 5s ago
  Process: 3069 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 3070 (keepalived)
    Tasks: 3
   CGroup: /system.slice/keepalived.service
           ├─3070 /usr/sbin/keepalived -D
           ├─3071 /usr/sbin/keepalived -D
           └─3072 /usr/sbin/keepalived -D

Jan 16 12:24:22 node2 Keepalived_healthcheckers[3071]: Activating healthchecker for service [10.10.10.3]:1358
Jan 16 12:24:25 node2 Keepalived_vrrp[3072]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 f...80.93
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 12:24:26 node2 Keepalived_vrrp[3072]: Sending gratuitous ARP on ens33 for 192.168.80.93

# 在node1节点上抓包测试
[root@node1 keepalived]# tcpdump -i ens33 -nn host 224.1.105.33
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens33, link-type EN10MB (Ethernet), capture size 262144 bytes
12:25:16.821399 IP 192.168.80.230 > 224.1.105.33: VRRPv2, Advertisement, vrid 33, prio 96, authtype simple, intvl 1s, length 20
12:25:17.822579 IP 192.168.80.230 > 224.1.105.33: VRRPv2, Advertisement, vrid 33, prio 96, authtype simple, intvl 1s, length 20

启动node1节点keepalived：

[root@node1 keepalived]# systemctl start keepalived
[root@node1 keepalived]# ifconfig

...
ens33:0: flags=4163  mtu 1500
        inet 192.168.80.93  netmask 255.255.255.255  broadcast 0.0.0.0
        ether 00:0c:29:44:bc:b6  txqueuelen 1000  (Ethernet)
...
[root@node1 keepalived]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-01-16 16:42:49 CST; 5s ago
  Process: 6090 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 6091 (keepalived)
    Tasks: 3
   CGroup: /system.slice/keepalived.service
           ├─6091 /usr/sbin/keepalived -D
           ├─6092 /usr/sbin/keepalived -D
           └─6093 /usr/sbin/keepalived -D

Jan 16 16:42:49 node1 Keepalived_vrrp[6093]: VRRP_Instance(VI_1) forcing a new MASTER election
Jan 16 16:42:50 node1 Keepalived_vrrp[6093]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 f...80.93
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 16:42:51 node1 Keepalived_vrrp[6093]: Sending gratuitous ARP on ens33 for 192.168.80.93
Hint: Some lines were ellipsized, use -l to show in full.

# node2节点抓包测试
[root@node2 keepalived]# tcpdump -i ens33 -nn host 224.1.105.33
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens33, link-type EN10MB (Ethernet), capture size 262144 bytes
16:45:21.875150 IP 192.168.80.136 > 224.1.105.33: VRRPv2, Advertisement, vrid 33, prio 100, authtype simple, intvl 1s, length 20
16:45:22.876093 IP 192.168.80.136 > 224.1.105.33: VRRPv2, Advertisement, vrid 33, prio 100, authtype simple, intvl 1s, length 20

双主模式配置

# node1节点上修改keepalived.cnf配置文件，在最后添加如下内容
vrrp_instance VI_2 {
    stat BACKUP
    interface ens33
    virtual_router_id 34
    priority 96
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass XXXX1111
    }
    virtual_ipaddress {
        192.168.80.93 dev ens33 label ens33:0
    }
}

# node2节点上修改keepalived.conf配置文件，在最后添加如下内容
vrrp_instance VI_2 {
    state MASTER
    interface ens33
    virtual_router_id 34
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass XXXX1111
    }
    virtual_ipaddress {
        192.168.80.93 dev ens33 label ens33:0
    }
}

# 停止keepalived服务，再重新启动
[root@node2 keepalived]# systemctl stop keepalived
[root@node2 keepalived]# systemctl start keepalived
[root@node2 keepalived]# ip a l
...
2: ens33:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:40:ee:7c brd ff:ff:ff:ff:ff:ff
    inet 192.168.80.230/24 brd 192.168.80.255 scope global noprefixroute dynamic ens33
       valid_lft 62510sec preferred_lft 62510sec
    inet 192.168.80.93/32 scope global ens33:0
       valid_lft forever preferred_lft forever
    inet6 fe80::9c20:6c3a:b648:5b22/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
    inet6 fe80::5291:5f99:50eb:805/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
...

[root@node2 keepalived]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-01-16 17:37:47 CST; 6min ago
  Process: 6300 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 6302 (keepalived)
    Tasks: 3
   CGroup: /system.slice/keepalived.service
           ├─6302 /usr/sbin/keepalived -D
           ├─6303 /usr/sbin/keepalived -D
           └─6304 /usr/sbin/keepalived -D

Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Adding sorry server [192.168.200.200]:1358 to VS [10.1...1358
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Removing alive servers from the pool for VS [10.10.10.2]:1358
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Remote SMTP server [127.0.0.1]:25 connected.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: SMTP alert successfully sent.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Timeout connecting server [192.168.201.100]:443.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Check on service [192.168.201.100]:443 failed after 3 retry.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Removing service [192.168.201.100]:443 from VS [192.16...:443
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Lost quorum 1-0=1 > 0 for VS [192.168.200.100]:443
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Remote SMTP server [127.0.0.1]:25 connected.
Jan 16 17:38:15 node2 Keepalived_healthcheckers[6303]: SMTP alert successfully sent.
Hint: Some lines were ellipsized, use -l to show in full.
You have new mail in /var/spool/mail/root

# 重新启动node1节点的keepalived服务
[root@node1 keepalived]# systemctl start keepalived
[root@node1 keepalived]# ip a l
...
2: ens33:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:44:bc:b6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.80.136/24 brd 192.168.80.255 scope global noprefixroute dynamic ens33
       valid_lft 62131sec preferred_lft 62131sec
    inet 192.168.80.93/32 scope global ens33:0
       valid_lft forever preferred_lft forever
    inet6 fe80::5291:5f99:50eb:805/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
...

[root@node1 keepalived]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-01-16 17:44:08 CST; 10s ago
  Process: 6681 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 6682 (keepalived)
    Tasks: 3
   CGroup: /system.slice/keepalived.service
           ├─6682 /usr/sbin/keepalived -D
           ├─6683 /usr/sbin/keepalived -D
           └─6684 /usr/sbin/keepalived -D

Jan 16 17:44:15 node1 Keepalived_healthcheckers[6683]: Timeout connecting server [192.168.200.4]:1358.
Jan 16 17:44:15 node1 Keepalived_healthcheckers[6683]: Timeout connecting server [192.168.200.5]:1358.
Jan 16 17:44:16 node1 Keepalived_vrrp[6684]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 17:44:16 node1 Keepalived_vrrp[6684]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 f...80.93
Jan 16 17:44:16 node1 Keepalived_vrrp[6684]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 17:44:16 node1 Keepalived_vrrp[6684]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 17:44:16 node1 Keepalived_vrrp[6684]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 17:44:16 node1 Keepalived_vrrp[6684]: Sending gratuitous ARP on ens33 for 192.168.80.93
Jan 16 17:44:17 node1 Keepalived_healthcheckers[6683]: Timeout connecting server [192.168.200.3]:1358.
Jan 16 17:44:17 node1 Keepalived_healthcheckers[6683]: Timeout connecting server [192.168.201.100]:443.
Hint: Some lines were ellipsized, use -l to show in full.
[root@node1 keepalived]# vim keepalived.conf
You have new mail in /var/spool/mail/root

# 在node2节点上status查看状态
[root@node2 keepalived]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-01-16 17:37:47 CST; 6min ago
  Process: 6300 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 6302 (keepalived)
    Tasks: 3
   CGroup: /system.slice/keepalived.service
           ├─6302 /usr/sbin/keepalived -D
           ├─6303 /usr/sbin/keepalived -D
           └─6304 /usr/sbin/keepalived -D

Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: SMTP alert successfully sent.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Timeout connecting server [192.168.201.100]:443.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Check on service [192.168.201.100]:443 failed after 3 retry.
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Removing service [192.168.201.100]:443 from VS [192.16...:443
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Lost quorum 1-0=1 > 0 for VS [192.168.200.100]:443
Jan 16 17:38:14 node2 Keepalived_healthcheckers[6303]: Remote SMTP server [127.0.0.1]:25 connected.
Jan 16 17:38:15 node2 Keepalived_healthcheckers[6303]: SMTP alert successfully sent.
Jan 16 17:44:09 node2 Keepalived_vrrp[6304]: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 96
Jan 16 17:44:09 node2 Keepalived_vrrp[6304]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 16 17:44:09 node2 Keepalived_vrrp[6304]: VRRP_Instance(VI_1) removing protocol VIPs.
Hint: Some lines were ellipsized, use -l to show in full.

通知脚本使用方式

#编辑通知脚本
#!/bin/bash
#keepalived 邮件通知脚本
#date:2019-1-16
contact = 'root@localhost'
notify () {
    local mailsubject="$(hostname) to be $1 vip floating"
    local mailbody="$(date + '%F %T'): vrrp transition, $(hostname) changed to be $1"
    echo "$mailbody" | mail -s "$mailsubject" $contact
}

case $1 in
master)
    notify master
    ;;
backup)
    notify backup
    ;;
fault)
    notify fault
    ;;
*)
    echo "Usage: $(basename $0) {master|backup|fault}"
    exit 1
    ;;
esac

# 在keepalived.conf中的vrrp实例中添加如下内容
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 33
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.80.93 dev ens33 label ens33:0
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
}

以dr集群架构配置示例

dr架构.png

[root@node1 keepalived]# yum install -y ipvsadm    #安装ipvsadm以便查看生成的规则
# 编辑keepalived.conf为node1和node2生成规则
[root@node1 keepalived]# vim keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
    root@localhost
   }
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node1
    vrrp_mcast_group4 224.1.105.33
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 33
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.80.93 dev ens33 label ens33:0
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
}

virtual_server 192.168.80.93 80 {
    delay_loop 1
    lb_algo wrr
    lb_kind DR
    protocol TCP
    sorry_server 127.0.0.1 80

    real_server 192.168.80.176 80 {
        weight 1
        HTTP_GET {
            url {
              path /index.html
              status_conde 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.80.85 80 {
        weight 1
        HTTP_GET {
            url {
              path /index.html
              status_conde 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
# 将此配置文件拷贝到node2节点,并修改以下几行
    router_id node2
    state BACKUP
    priority 96
# 重新启动node2节点的keepalived服务
[root@node2 keepalived]# systemctl stop keepalived
[root@node2 keepalived]# systemctl start keepalived
[root@node2 keepalived]# ifconfig
...
ens33:0: flags=4163  mtu 1500
        inet 192.168.80.93  netmask 255.255.255.255  broadcast 0.0.0.0
        ether 00:0c:29:40:ee:7c  txqueuelen 1000  (Ethernet)
...

[root@node2 keepalived]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.80.93:80 wrr
  -> 192.168.80.85:80             Route   1      0          0         
  -> 192.168.80.176:80            Route   1      0          0

# 启动node1的keepalived服务,通过下面查看ip和status后看到node1已经成功上线
[root@node2 keepalived]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.80.93:80 wrr
  -> 192.168.80.85:80             Route   1      0          0         
  -> 192.168.80.176:80            Route   1      0          0

# 使用client访问服务正常
[root@localhost ~]# curl http://192.168.80.93
RealServer 1
[root@localhost ~]# curl http://192.168.80.93
RealServer 2

HA Cluster和keepalived主从,主主高可用设置以及varnish缓存机制（一）

一、简述HA cluster原理

高可用集群的衡量标准

二、keepalived

三、Keepalived实现主从、主主架构

RealServer 1

RealServer 2

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