Haproxy+Keepalived高可用双机单活

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