## 1.需求

實現資料交換系統的主備自動切換功能，當資料交換的master主機故障,網路故障以及資料交換mysql服務出現故障時，能自動切換到備機執行。

## 2.實現思路

採用keepalived+rsync+ inotify雙backup模式，並設定不搶佔資源。當master掛機，切換為backup,完成修復後，不會搶佔為maste!避免不必要的切換。 假設兩臺主機如下。
•    master host：192.168.1.151，debain
•    backup host：192.168.1.152，debain

安裝步驟如下：
1.    安裝apt-get install keepalived
2.    安裝apt-get install rsync
3.    安裝apt-get install inotify-tools
4.    啟動

## 3.安裝keeplived

```
 apt-get install keeplived
```

#### 修改master主機上的/etc/keepalived/keepalived.conf配置檔案

```
 cat /etc/keepalived/keepalived.conf
```


```
! Configuration File for keepalived

global_defs {
   router_id xchange_router     # all node must same
}

vrrp_instance xchange {
    state BACKUP                   # master or backup
    interface eth1                 # 熱備通訊網口
    virtual_router_id 55           # all node must same
    priority  100                  # 優先順序，高的先執行。主機異常時切換到低優先順序熱備機，副機一般設為99
    advert_int 1                   # send keepalived msg every 1 second
    nopreempt                      # must need
    authentication {               # all node must same
        auth_type PASS
        auth_pass 1111
    }

    track_interface { #需要檢測的其它
        eth0          #在些新增的網路介面會被檢測，eth0不正常會切換熱備服務
    }

    notify_master /etc/keepalived/to_master.sh  #切換為master時執行
    notify_backup /etc/keepalived/to_backup.sh  #切換為backup時執行
}
virtual_server 127.0.0.1 3306 { #表示需要檢測的服務
    delay_loop 2
    lb_algo rr
    lb_kind NAT
    persistence_timeout 60
    protocol TCP
    real_server 127.0.0.1 3306 {
    weight 3
    notify_down /etc/keepalived/shutdown.sh #服務檢測失敗執行操作
    TCP_CHECK {
    connect_timeout 10
    nb_get_retry 3
    delay_before_retry 3
    connect_port 3306
    }
}
```

#### 修改backup主機上的/etc/keepalived/keepalived.conf

```
! Configuration File for keepalived

global_defs {
   router_id xchange_router     # all node must same
}

vrrp_instance xchange {
    state BACKUP                   # master or backup
    interface eth1                 # 熱備通訊網口
    virtual_router_id 55           # all node must same
    priority  99                   # 優先順序，高的先執行。主機異常時切換到低優先順序熱備機，副機一般設為99
    advert_int 1                   # send keepalived msg every 1 second
    #nopreempt                     # must need
    authentication {               # all node must same
        auth_type PASS
        auth_pass 1111
    }

    track_interface { #需要檢測的其它
        eth0          #在些新增的網路介面會被檢測，eth0不正常會切換熱備服務
    }

    notify_master /etc/keepalived/to_master.sh  #切換為master時執行
    notify_backup /etc/keepalived/to_backup.sh  #切換為backup時執行
}
virtual_server 127.0.0.1 3306 { #表示需要檢測的服務
    delay_loop 2
    lb_algo rr
    lb_kind NAT
    persistence_timeout 60
    protocol TCP
    real_server 127.0.0.1 3306 {
    weight 3
    notify_down /etc/keepalived/shutdown.sh #服務檢測失敗執行操作
    TCP_CHECK {
    connect_timeout 10
    nb_get_retry 3
    delay_before_retry 3
    connect_port 3306
    }
}

```

#### 建立shell指令碼，放在/etc/keepalived目錄下

> 指令碼1：shutdown.sh

```

#!/bin/bash
echo "shutdown.sh" >> /var/log/messages
killall keepalived
/etc/init.d/manager stop

```

>指令碼2：to_master.sh

```

#!/bin/bash
echo "to_master" >> /var/log/messages
/etc/init.d/manager stop
/etc/init.d/manager start

```

>指令碼3:to_backup.sh

```
#!/bin/bash

echo "to_backup" >> /var/log/messages
/etc/init.d/manager stop


```

>指令碼4:keepalived_sync.sh,

```
#!/bin/bash

# usage: sh keepalived_sync.sh
 
USER=appbackup            # the account to login rsyc server. Notice, it's not the linux user
IP=192.168.1.152           # the rsync server's ip.主備對應修改，192.168.1.151/192.168.1.152
DES="xchange"
SRC="/usr/app/xchange/repository"
PASSWD_FILE="/etc/rsync_client.secret"
LOGFILE="/var/log/messages.log"

/usr/bin/inotifywait -mrq --timefmt '%d/%m/%y %H:%M' --format '%T %w%f%e' -e close_write,modify,delete,create,attrib,move ${src} |  while read file
do
/usr/bin/rsync -vzrtopg --delete --progress --password-file=$PASSWD_FILE $SRC

[email protected]$IP::$DES
echo "${files} was rsynced" >>$LOGFILE 2>&1
done


```

#### keepalived的相關配置檔案儲存位置如下：

```
[email protected]:/etc/keepalived$ tree /etc/keepalived/
/etc/keepalived/
├── keepalived.conf
├── to_backup.sh
├── shutdown.sh
├── to_master.sh
└── keepalived_sync.sh

1 directory, 5 files

```

## 安裝Rsync

```
apt-get install rsync
```

#### 修改/etc/default/rsync檔案

```
RSYNC_ENABLE=true
```

#### 配置rsyncd的/etc/rsyncd.conf

```
 cat /etc/rsyncd.conf
```

```
# sample rsyncd.conf configuration file

# GLOBAL OPTIONS

#motd file=/etc/motd
log file=/var/log/messages
# for pid file, do not use /var/run/rsync.pid if
# you are going to run rsync out of the init.d script.
# The init.d script does its own pid file handling,
# so omit the "pid file" line completely in that case.
# pid file=/var/run/rsyncd.pid
syslog facility=daemon
#socket options=

# MODULE OPTIONS

[xchange]

comment = public archive
path = /usr/app/xchange/repository
use chroot = yes
#    max connections=10
lock file = /var/lock/rsyncd
# the default for read only is yes...
read only = no
list = yes
uid = root
gid = root
#    exclude =
#    exclude from =
#    include =
#    include from =
auth users =appbackup
secrets file = /etc/rsyncd.secrets
strict modes = yes
#    hosts allow =
#    hosts deny =
ignore errors = no
ignore nonreadable = yes
transfer logging = no
#    log format = %t: host %h (%a) %o %f (%l bytes). Total %b bytes.
timeout = 600
refuse options = checksum dry-run
dont compress = *.gz *.tgz *.zip *.z *.rpm *.deb *.iso *.bz2 *.tbz

```

#### 修改/etc/rsync.secret

```
sudo cat /etc/rsync.secret
```

```
appbackup:passwd

```

> 修改/etc/rsync.secret檔案屬性:

```
 chown root:root /etc/rsync.secret
 chmod 600 /etc/rsync.secret
```

#### 啟動rsync伺服器

```
 service rsync restart
```

####  配置rsync客戶端,

> 檔案/etc/rsync_client.secret內容如下

```
passwd
```

> 修改檔案許可權
```
sudo chmod 600 /etc/rsync_client.secret
```

** 注意：如果不修改許可權，則會報錯ERROR: password file must not be other-accessible**

## 安裝 inotify-tools

```
apt-get install inotify-tools
```

## 5.啟動

#### 1. 啟動master主機上的rsync
```
 service rsync restart
```
#### 2. 啟動master主機上的keepalived
```
 service keepalived restart
```

#### 5. 檢視啟動日誌
```
tail -f /var/log/messages.log
```

## 6.自動切換測試

#### 確認keepalived、rsync已經啟動

```
ps -ef | grep keepalived
ps -ef | grep rsync
```
## 7.加入開機指令碼
#echo "/data/sh/inotifyrsync.sh &"  >> /etc/rc.local

## 8.manager去掉開機啟動

#### 切換測試

> 1.停止master主機上的mysql程序，檢視master主機上的manager服務是否停止，檢查backup主機是否啟動manager服務。
> 2.或者關機master，查backup主機是否啟動manager服務。


執行流程說明：
預設情況下主副機器都不會執行manager服務，主副機啟動keepalived服務，首行執行優先順序高的主機to_master指令碼，啟動manager服務,如果出現mysql停止或宕機情況，會執行shutdown.sh停止熱備和manager服務，此時主副切換，副機執行to_master指令碼,過程中如果主機修復，主機會搶佔熱備服務，副機執行to_backup指令碼並停止manager服務，主機重新執行to_master並開啟manager