Keepalived主備

這裏咱們僅僅只利用Keepalived作雙機熱備，也就是保證服務器的高可用性，其餘的不用管。

1、Keepalived雙機熱備的應用場景

2、Keepalived雙機熱備的特性以及優缺點

  特性：
  1，至少須要兩臺服務器，其中一臺爲master始終提供服務，另一臺做爲backup始終處於空閒狀態，只有在主服務器掛掉的時候他就來幫忙了，這是典型的雙機熱備
  2，能根據需求判斷服務是否可用，在不可用的時候要即便切換   優缺點：
  優勢：數據同步很是簡單，不像負載均衡對數據一致性要求很是高，實現起來相對複雜維護也頗爲不便，雙機熱備用rsync就能夠實現了操做和維護很是簡單
  缺點：服務器有點浪費，始終有一臺處於空閒狀態

3、Keepalived雙機熱備的配置

  首先畫個雙機熱備拓撲圖吧：

Keepalived安裝

  操做系統：Linux6.3 2.6.32

  下載軟件
  keepalived官方地址：http://www.keepalived.org/download.html

你們能夠到這裏下載最新版本的keepalived（若是已經提供用提供的安裝包keepalived-1.2.15.tar.gz）
  建立目錄、壓縮文件上傳、解壓（主備機進行相同操做）

mkdir -p /usr/local/HAsoft  
cd /usr/local/HAsoft  
tar -zxvf keepalived-1.2.15.tar.gz
cd keepalived-1.2.15

  預編譯

./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.32-279.el6.x86_64/

  （kernels後面的版本「2.6.32-279.el6.x86_64」以實際安裝linux版本爲準，不要複製直接按Tab鍵自動補全便可） 結果以下：（出現以下相似結果就行）

Keepalived configuration  
------------------------
Keepalived version       : 1.2.15  
Compiler      : gcc  
Compiler flags               : -g -O2   -DETHERTYPE_IPV6=0x86dd  
Extra Lib                : -lssl -lcrypto   -lcryptUse IPVS Framework          : Yes  
IPVS sync daemon support     : Yes  
IPVS use libnl    : No  
Use VRRP Framework           : Yes  
Use Debug flags              : No

  編譯

make && make install

  整理管理文件：

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/

  創建配置文件目錄

mkdir -p /etc/keepalived/

  注意：keepalived的配置文件默認在/etc/keepalived/目錄 兩臺服務器(兩個節點)都這樣安裝便可

配置 打開配置文件：（該文件不存在，需手動建立）

vim /etc/keepalived/keepalived.conf

  按i鍵將下面主機配置的內容複製粘貼到keepalived.conf中，並按時間環境修改標紅的配置項。

  主機配置

global_defs
{
 }
vrrp_instance N1 {            //定義一個vrrp組 
state MASTER                //指定哪一個爲master（主機），哪一個爲backup（備機）。
mcast_src_ip 192.166.66.80    //此處ip填寫本機ip便可（非必要設置）
interface eth2               //設置實例綁定的網卡
virtual_router_id 51          // VPID標記 (主機備機要一致)
priority 100                 //定義優先級，數字越大，優先級越高 
authentication {             //驗證類型和密碼 
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {          //虛擬IP 
192.166.66.85              
}
}

  備機配置

vim /etc/keepalived/keepalived.conf

  將下面內容複製到keepalived.cong中，並按實際環境修改標紅配置項。

global_defs
{
}
vrrp_instance N1 {
state BACKUP
interface eth2
mcast_src_ip 192.166.66.81
virtual_router_id 51
priority 88
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
192.166.66.85
}
}

4、啓動調試

  在節點A即主機上啓動keepalive

/etc/init.d/keepalived start

  啓動日誌：（/var/log/message）

tail -f /var/log/messages
Sep  8 18:26:02 centosaKeepalived_vrrp: Registering Kernel netlink reflector
Sep  8 18:26:02 centosaKeepalived_vrrp: Registering Kernel netlink command channel
Sep  8 18:26:02 centosaKeepalived_vrrp: Registering gratutious ARP shared channel
Sep  8 18:26:02 centosaKeepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Sep  8 18:26:02 centosaKeepalived_vrrp: Configuration is using : 36076 Bytes
Sep  8 18:26:02 centosaKeepalived_vrrp: Using LinkWatch kernel netlink reflector...
Sep  8 18:26:02 centosa Keepalived: Starting VRRP child process, pid=5606
Sep  8 18:26:07 centosaKeepalived_vrrp: VRRP_Instance(lnmp) Transition to MASTER STATE
Sep  8 18:26:12 centosaKeepalived_vrrp: VRRP_Instance(lnmp) Entering MASTER STATE
Sep  8 18:26:12 centosaavahi-daemon[2528]: Registering new address record for 192.168.17.200 on eth0.

  在節點B即備機上上啓動

/etc/init.d/keepalived start

  啓動日誌：

tail -f /var/log/messages
Sep  8 18:30:02 centosb Keepalived: Starting Keepalived v1.2.2 (09/08,2011)
Sep  8 18:30:02 centosb Keepalived: Starting Healthcheck child process, pid=5837
Sep  8 18:30:02 centosbKeepalived_vrrp: Registering Kernel netlink reflector
Sep  8 18:30:02 centosbKeepalived_vrrp: Registering Kernel netlink command channel
Sep  8 18:30:02 centosbKeepalived_vrrp: Registering gratutious ARP shared channel
Sep  8 18:30:02 centosb Keepalived: Starting VRRP child process, pid=5839
Sep  8 18:30:02 centosb kernel: IPVS: Registered protocols (TCP, UDP, AH, ESP)
Sep  8 18:30:02 centosb kernel: IPVS: Connection hash table configured (size=4096, memory=32Kbytes)
Sep  8 18:30:02 centosb kernel: IPVS: ipvs loaded.
Sep  8 18:30:02 centosbKeepalived_healthcheckers: Registering Kernel netlink reflector
Sep  8 18:30:02 centosbKeepalived_healthcheckers: Registering Kernel netlink command channel
Sep  8 18:30:02 centosbKeepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'.
Sep  8 18:30:02 centosbKeepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Sep  8 18:30:02 centosbKeepalived_vrrp: Configuration is using : 36252 Bytes
Sep  8 18:30:02 centosbKeepalived_vrrp: Using LinkWatch kernel netlink reflector...
Sep  8 18:30:02 centosbKeepalived_healthcheckers: Configuration is using : 6271 Bytes
Sep  8 18:30:02 centosbKeepalived_healthcheckers: Using LinkWatch kernel netlink reflector...
Sep  8 18:30:02 centosbKeepalived_vrrp: VRRP_Instance(lnmp) Entering BACKUP STATE

  從日誌能夠看出，啓動都沒有問題，而且安裝我給的優先級完成了競選，各自成就了各自的狀態
  在本機運行cmd命令 Ping 192.168.17.200 看可否正常ping通。
  關閉節點A主機的服務測試切換是否正常

/etc/init.d/keepalived stop

  觀察節點B的日誌：

Sep  8 18:32:55 centosbKeepalived_vrrp: VRRP_Instance(lnmp) Transition to MASTER STATE
Sep  8 18:33:00 centosbKeepalived_vrrp: VRRP_Instance(lnmp) Entering MASTER STATE
Sep  8 18:33:00 centosbavahi-daemon[2531]: Registering new address record for 192.168.17.200 on eth0.

  在本機運行cmd命令 Ping 192.168.17.200 看可否正常ping通。
  啓動節點A的服務測試切換是否正常

/etc/init.d/keepalived start

  觀察節點B的日誌：

Sep  8 18:33:31 centosbKeepalived_vrrp: VRRP_Instance(lnmp) Received higher prio advert
Sep  8 18:33:31 centosbKeepalived_vrrp: VRRP_Instance(lnmp) Entering BACKUP STATE
Sep  8 18:33:31 centosbavahi-daemon[2531]: Withdrawing address record for 192.168.17.200 on eth0.

  在本機運行cmd命令 Ping 192.168.17.200 看可否正常ping通。
  注意把keepalived寫在開機啓動裏面 準備機同時設置

vim /etc/rc.local

  輸入下面內容保存

service keepalived start