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Haproxy+Keepalived高可用双机单活

发表于: 2015-01-06   作者:bylijinnan   来源:转载   浏览:
摘要: 我们的应用MyApp不支持集群,但要求双机单活(两台机器:master和slave): 1.正常情况下,只有master启动MyApp并提供服务 2.当master发生故障时,slave自动启动本机的MyApp,同时虚拟IP漂移至slave,保持对外提供服务的IP和端口不变 F5据说也能满足上面的需求,但F5的通常用法都是双机双活,单活的话还没研究过 服务器资源 10.7
我们的应用MyApp不支持集群,但要求双机单活(两台机器:master和slave):
1.正常情况下,只有master启动MyApp并提供服务
2.当master发生故障时,slave自动启动本机的MyApp,同时虚拟IP漂移至slave,保持对外提供服务的IP和端口不变

F5据说也能满足上面的需求,但F5的通常用法都是双机双活,单活的话还没研究过

服务器资源
10.75.201.2:虚拟IP(VIP),与master和slave在同一子网;以此IP对外暴露服务
10.75.201.67(master):安装MyApp+ Haproxy + Keepalived
10.75.201.66(slave):安装MyApp+ Haproxy + Keepalived


网络策略
10.75.201.2:8000 <-> 10.75.201.67:9000
10.75.201.2:8000 <-> 10.75.201.66:9000


系统安装

Haproxy安装及配置
同时安装在master和slave

1. 拷贝安装文件到/app/risk/ha下

2. 使用root用户安装haproxy
tar -xvf haproxy-1.4.24.tar.gz
cd haproxy-1.4.24
make TARGET=linux26 ARCH=x86_64
make install

3. 使用risk用户配置haproxy,创建文件/app/risk/ha/haproxy.cfg,粘贴如下内容
global
 log     127.0.0.1 alert
 log     127.0.0.1 alert debug

defaults
 log        global
 mode       http
 option     dontlognull
 option     redispatch
 retries    3
 contimeout 10800000
 clitimeout 10800000
 srvtimeout 10800000

listen MyApp 10.75.201.2:8000
 mode    tcp
 balance roundrobin
 option  tcpka
 server  MyApp01 10.75.201.67:9000 check inter 5000 downinter 500
 server  MyApp02 10.75.201.66:9000 check inter 5000 backup

以10.75.201.2:8000对外提供服务,后端是主备两台机器:10.75.201.67:9000和10.75.201.66:9000

使用HAProxy遇到的问题:

a.
[WARNING] 003/191909 (20413) : config : 'stats' statement ignored for proxy 'MyApp' as it requires HTTP mode.
[WARNING] 003/191909 (20413) : config : 'option forwardfor' ignored for proxy 'MyApp' as it requires HTTP mode
原因是:
mode tcp是基于第4层(网络层),mode http是基于第7层(应用层),mode tcp不会检查http header
不同的mode可配置的选项不同,例如配置改成:
mode    http
stats   enable
option  forwardfor
就会提示上述错误
而MyApp是基于netty的TCP服务器,因此配置为mode tcp

b.
Starting proxy MyApp: cannot bind socket
原因是配置的8000端口被其他程序占用了,或者是重复启动haproxy


keepalived安装及配置
同时安装在master和slave,使用root用户操作


1. 依次安装如下package
rpm -Uvh keyutils-libs-devel-1.4-4.el6.x86_64.rpm
rpm -Uvh libcom_err-devel-1.41.12-14.el6.x86_64.rpm
rpm -Uvh libsepol-devel-2.0.41-4.el6.x86_64.rpm
rpm -Uvh libselinux-devel-2.0.94-5.3.el6.x86_64.rpm
rpm -Uvh krb5-devel-1.10.3-10.el6.x86_64.rpm
rpm -Uvh zlib-devel-1.2.3-29.el6.x86_64.rpm
rpm -Uvh openssl-devel-1.0.0-27.el6.x86_64.rpm


2. 解压keepalived-1.2.12.tar.gz,跳转到目录下编译安装
./configure
make
make install


修改/etc/keepalived/keepalived.conf(interface值用ifconfig确认一下)
master:
vrrp_script check_MyApp {
    script "/app/risk/MyApp/shell/check_MyApp.sh"   # verify the port is listening 
    interval 2                    # check every 2 seconds
}
vrrp_instance VI_1 {
    interface eth1                # interface to monitor
    state MASTER
    virtual_router_id 11          # Assign one ID for this route
    priority 101                  # 101 on master, 100 on backup
    virtual_ipaddress {
        10.75.201.2            # the virtual IP
    }
    track_script {
        check_MyApp
    }
    notify_stop "/app/risk/MyApp/shell/stopAll.sh"
}

slave:
vrrp_script check_MyApp {
    script "killall -0 haproxy"   # verify the haproxy is running
    interval 2                    # check every 2 seconds
}
vrrp_instance VI_1 {
    interface eth1                # interface to monitor
    state BACKUP
    virtual_router_id 11          # Assign one ID for this route
    priority 100                  # 101 on master, 100 on backup
    virtual_ipaddress {
        10.75.201.2            # the virtual IP
    }
    track_script {
        check_MyApp
    }
    notify "/app/risk/MyApp/shell/keepalivednotify.sh"
}


说明:
a. master中的vrrp_script 是check_MyApp.sh,它定时检查MyApp(提供服务的端口是否起来),若down掉,则停掉keepalived,使得slave能接管服务并成为master:
#!/bin/bash
#if MyApp is down, stop keepalived

PORT=9000
nc -z 127.0.0.1 $PORT 1>/dev/null 2>&1; result=$?;
if [ $result -eq 0 ]; then
    exit 0
else
    service keepalived stop
    . ./log.sh "keepalived stopped"
    exit 1
fi


b.master中notify_stop的作用是service keepalived stop后,把MyApp关掉,确保“单活”;但如果是直接kill掉keepalived进程的话,是不会触发notify_stop的,应该避免这样做。同时,salve中notify的作用是,当slave转换成master后,启动本机的MyApp的同时,远程调用shell脚本把原master的MyApp停掉,确保“单活”

c. slave中vrrp_script 则简单地检查Haproxy是否正常,由于haproxy是一直开着的,因此slave会进入BACKUP状态


d.虚拟IP(10.75.201.2)并不需要对应一台机器,只要求跟master和slave的IP是同一子网就可以了

e.keepalivednotify.sh的主要作用就是当slave进入MASTER状态时,启动本机的MyApp,同时把之前master的MyApp停掉:

#!/bin/bash

LOCAL=10.75.201.66
REMOTE=10.75.201.67
PORT=9000
NOW=`date "+%Y-%m-%d %H:%M:%S"`


startLocal(){
         nc -z $LOCAL $PORT 1>/dev/null 2>&1; result=$?;
         if [ $result -eq 0 ]; then
             echo $NOW-$LOCAL:$PORT 'is listening! No need to restart!'
         else
             . /app/risk/MyApp/shell/startAll.sh
             echo $NOW-'start at' $LOCAL:$PORT 'ok'
         fi
}


#startRemote(){
#         nc -z $REMOTE $PORT 1>/dev/null 2>&1; result=$?;
#         if [ $result -eq 0 ]; then
#             echo $NOW-$REMOTE:$PORT 'is listening! No need to restart!'
#         else
#             ssh root@$REMOTE "sh /app/risk/MyApp/shell/startAll.sh"
#             echo $NOW-'start at' $REMOTE:$PORT 'ok'
#         fi
#}

stopRemote(){
        nc -z $REMOTE $PORT 1>/dev/null 2>&1; result=$?;
        if [ $result -eq 0 ]; then
            ssh root@$REMOTE "sh /app/risk/MyApp/shell/stopAll.sh"
        fi
}

stopLocal(){
        nc -z $LOCAL $PORT 1>/dev/null 2>&1; result=$?;
        if [ $result -eq 0 ]; then
            . /app/risk/MyApp/shell/stopAll.sh
        fi
}

TYPE=$1
NAME=$2
STATE=$3

case $STATE in
        "MASTER") 
                  startLocal 
                  stopRemote
                  exit 0
                  ;;
        "BACKUP") 
                  stopLocal
                  exit 0
                  ;;
        "FAULT")  
                  stopLocal
                  exit 0
                  ;;
        *)        echo "unknown state"
                  exit 1
                  ;;
esac



keepalived的其他相关配置:
1. 让keepalived作为linux服务自启动
cd /etc/sysconfig
ln -s /usr/local/etc/sysconfig/keepalived .
cd /etc/rc3.d/
ln -s /usr/local/etc/rc.d/init.d/keepalived S100keepalived
cd /etc/init.d/
ln -s /usr/local/etc/rc.d/init.d/keepalived .


2. 让keepalived启动时输出详细信息,修改/usr/local/etc/sysconfig/keepalived
修改为KEEPALIVED_OPTIONS="-D -d"

3. 让主机可绑定非本地IP
echo "net.ipv4.ip_nonlocal_bind = 1" >> /etc/sysctl.conf
sysctl -p



使用keepalived遇到的问题:
a.虚拟IP绑定不成功
可以尝试service network restart,同时注意启动keepalived使用绝对路径的配置文件,例如:
keepalived -f /app/risk/ha/keepalived.conf
而不要这样:
cd /app/risk/ha
keepalived -f ./keepalived.conf
具体原因不明

如果不指定keepalived的配置文件的话,默认是读取/etc/keepalived/keepalived.conf文件
强烈建议使用/etc/keepalived/keepalived.conf(没有这个文件则创建一个)
这个默认的路径可以在/usr/local/etc/rc.d/init.d/keepalived中看到:
#!/bin/sh
#
# Startup script for the Keepalived daemon
#
# processname: keepalived
# pidfile: /var/run/keepalived.pid
# config: /etc/keepalived/keepalived.conf
# chkconfig: - 21 79
# description: Start and stop Keepalived

# Source function library
. /etc/rc.d/init.d/functions

# Source configuration file (we set KEEPALIVED_OPTIONS there)
. /etc/sysconfig/keepalived


......


b.执行service keepalived start报错:
Starting keepalived: /bin/bash: keepalived: command not found

keepalived这个命令在:
/usr/local/sbin/keepalived

而echo $PATH确认/usr/local/sbin/是在PATH里面的

这个问题非常奇怪,不知是什么原因

上网搜索一下,解决方案有两个:
一是把keepalived拷贝到/usr/sbin/:

cp /usr/local/sbin/keepalived /usr/sbin/

二是修改启动脚本/etc/init.d/keepalived,把start方法当中启动命令修改为全路径:

daemon /usr/local/sbin/keepalived ${KEEPALIVED_OPTIONS}

c.其他错误
需要检查各个shell脚本是否有执行权限,以及shell脚本中是否有windows字符(dos2unix)


启动
1. 使用risk用户启动master的MyApp(slave不启动MyApp)
/app/risk/MyApp/shell/startAll.sh

2. 使用risk用户启动master和slave的haproxy
nohup haproxy -f /app/risk/ha/haproxy.cfg &
nohup haproxy -f /app/risk/ha/haproxy.cfg &

3. 使用root用户启动master和slave的keepalived.
service keepalived start

测试验证
1. 查看MyApp状态
netstat -anp | grep 9000
2. 查看Haproxy状态
ps -ef | grep haproxy
3. 查看keepalived状态
ps –ef | grep keepalived
cat /var/log/messages | grep VRRP_Instance
或tail –f /var/log/messages
4. 虚拟IP绑定状态
ip a | grep eth



正常情况下:
1. 虚拟IP绑定在master上
在master上执行命令ip add | grep eth1:
eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UNKNOWN qlen 1000
inet 10.75.201.67/24 brd 10.75.201.255 scope global eth1
inet 10.75.201.2/32 scope global eth1
可见绑定了虚拟IP(10.75.201.2)

2. master的keepalived状态为MASTER(在master上执行命令tail –f /var/log/messages):
localhost Keepalived_healthcheckers[23359]: Using LinkWatch kernel netlink reflector...
localhost Keepalived_vrrp[23360]: VRRP_Script(check_MyApp) succeeded
localhost Keepalived_vrrp[23360]: VRRP_Instance(VI_1) Transition to MASTER STATE
localhost Keepalived_vrrp[23360]: VRRP_Instance(VI_1) Received lower prio advert, forcing new election
localhost Keepalived_vrrp[23360]: VRRP_Instance(VI_1) Entering MASTER STATE

3. slave的keepalived为BACKUP状态(命令同上)
localhost Keepalived_vrrp[5161]: VRRP_Instance(VI_1) Entering BACKUP STATE

测试master有故障的情况:
1. 把master的MyApp进程kill掉
2. 把master的keepalived服务停掉:service keepalived stop
3. 把master的keepalived进程kill掉(此时master上的MyApp不会停掉,需要手动关掉,应该避免这种情况)
以上任意一种情况发生,都会使得slave转换到MASTER状态并且虚拟IP漂移至slave,同时slave的MyApp会自动启动



Haproxy+Keepalived高可用双机单活

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