keepalived架设简单高可用的nginx的web服务器----那些你不知道的秘密

如果負載均衡軟件不使用LVS的話，那麼keepalived的配置是相當的簡單的，只需要配置好MASTER和SLAVE的vrrp相關配置就可以了，後端realServer的偵測就可以交給負載均衡軟件去做，比如我使用的負載均衡軟件是haproxy，個人認為比LVS更高效、更省資源、配置更簡單、條理更清晰。

下面來說說我在配置keepalived和nginx過程中遇到的一些問題，之所以會出現很多問題，關鍵就在於keepalived沒有配置文件查錯的機制，不管你的配置文件寫成了啥樣，你照樣可以成功啟動keepalived，它不會給你任務錯誤提示，就像它沒有出錯一樣，你查看進程時也不會覺得它異常，和普通的正常的進程一模一樣，因此一旦配置文件配置錯誤就很要命了。

test2 eth2:192.168.46.132
192.168.46.132
test3 eth2:192.168.46.133
192.168.46.133

如果你使用LVS作為負載均衡器的話，需要讓編譯程序能找到你的linux內核所在目錄，要帶 --with-kernel-dir=/usr/src/linux參數編譯，因此你需要先安裝內核開發包：
with-kernel-dir=/usr/src/linux參數編譯，因此你需要先安裝內核開發包：
yum install kernel-devel
這是CENTOS的安裝方法。
接著為內核源文件目錄做一個軟鏈接：
ln -s /usr/src/kernels/`uname -r` /usr/src/linux
現在可以開始編譯了：
./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/linux
with-kernel-dir=/usr/src/linux
如果不使用LVS，就不需要帶--with-kernel-dir參數，我用的是nginx，因此沒有指定此參數。
with-kernel-dir參數，我用的是nginx，因此沒有指定此參數。
configure結束，開始make時，出现了以下錯誤：
/usr/include/stdint.h:41: error: conflicting types for‘int64_t’
include/stdint.h:41: error: conflicting types for
include/stdint.h:41: error: conflicting types for‘int64_t’
/usr/src/linux/include/linux/types.h:126: error: previous declaration of ‘int64_t’ was here
include/linux/types.h:126: error: previous declaration of ‘int64_t’ was here
/usr/include/stdint.h:56: error: conflicting types for‘uint64_t’
include/stdint.h:56: error: conflicting types for
include/stdint.h:56: error: conflicting types for‘uint64_t’
/usr/src/linux/include/linux/types.h:124: error: previous declaration of ‘uint64_t’ was here
include/linux/types.h:124: error: previous declaration of ‘uint64_t’ was here
In file included from /usr/include/stdlib.h:438,
include/stdlib.h:438,
在源目錄裡找到keepalived/libipvs-2.6/ip_vs.h文件，編輯它，把 #include<linux/types.h> 移动到 #include<sys/types.h> 的下面即可，再次make正常，make install安裝完畢。
2.6/ip_vs.h文件，編輯它，把 #include
<linux/types.h> 移动到 #include
2.6/ip_vs.h文件，編輯它，把 #include<linux/types.h> 移动到 #include<sys/types.h> 的下面即可，再次make正常，make install安裝完畢。

/etc/keepalived/keepalived.conf
global_defs {
notification_email {
root@localhost
}
notification_email_from root@localhost
smtp_server 127.0.0.1
127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/root/nginx_pid.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state MASTER
interfaceeth2
virtual_router_id 51
mcast_src_ip 192.168.46.132
192.168.46.132
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.46.200/24
}
track_script {
chk_http_port
}
}

[root@test3 init.d]# vim /etc/keepalived/keepalived.conf
!Configuration File forkeepalived
forkeepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from root@localhost
smtp_server 127.0.0.1
127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/root/nginx_pid.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interfaceeth2
virtual_router_id 51
mcast_src_ip 192.168.46.133
192.168.46.133
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.46.200/24
}
track_script {
chk_http_port
}
}
~

[root@test2 init.d]# vim /root/nginx_pid.sh
#!/bin/bash
A=`ps -C nginx --no-header |wc -l`
if[ $A -eq 0];then
[ $A -eq 0
if[ $A -eq 0];then
kill -HUP `cat /usr/local/nginx/logs/nginx.pid`
sleep 3
if[ `ps -C nginx --no-header |wc -l` -eq 0];then
[ `ps -C nginx --no-header |wc -l` -eq 0
if[ `ps -C nginx --no-header |wc -l` -eq 0];then
killall keepalived
fi
fi