1. Nginx相關概念
1.1. 反向代理
反向代理（Reverse Proxy）方式是指以代理服務器來接受internet上的連接請求，然后將請求轉發給內部網絡上的服務器，并將從服務器上得到的結果返回給internet上請求連接的客戶端，此時代理服務器對外就表現為一個服務器。
1.2. 負載均衡
負載均衡，英文名稱為Load Balance，是指建立在現有網絡結構之上，并提供了一種廉價有效透明的方法擴展網絡設備和服務器的帶寬、增加吞吐量、加強網絡數據處理能力、提高網絡的靈活性和可用性。其原理就是數據流量分攤到多個服務器上執行，減輕每臺服務器的壓力，多臺服務器共同完成工作任務，從而提高了數據的吞吐量。
2. Nginx的安裝
2.1. 下載nginx
2.2. 上傳并解壓nginx
tar -zxvf nginx-1.8.1.tar.gz -C /usr/local/src
2.3. 編譯nginx
進入到nginx源碼目錄
cd /usr/local/src/nginx-1.8.1
檢查安裝環境,并指定將來要安裝的路徑
./configure --prefix=/usr/local/nginx
缺包報錯 ./configure: error: C compiler cc is not found
使用YUM安裝缺少的包
yum -y install gcc pcre-devel openssl openssl-devel
編譯安裝
make && make install
安裝完后測試是否正常：
/usr/loca/nginx/sbin/nginx
查看端口是否有ngnix進程監聽
netstat -ntlp | grep 80
3. 配置nginx
3.1. 配置反向代理
1.修改nginx配置文件（/usr/local/nginx/conf下的nginx.conf文件）
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upstream myproject{
#server 183.232.41.1;
server 42.156.140.7;
server 61.129.48.158;
}
server {
listen 80;
server_name nginx-01.itcast.cn; #nginx所在服務器的主機名
反向代理的配置
location / { #攔截所有請求
root html;
proxy_pass [http://192.168.0.21:8080;](http://192.168.0.21:8080/) #這里是代理走向的目標服務器：tomcat
#proxy_pass http://myproject;
}
}
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2.啟動tomcat-01上的tomcat
3.啟動nginx-01上的nginx
./nginx
重啟:
kill -HUP cat /usr/local/nginx/logs/nginx.pid
或者
/usr/local/nginx/sbin/nginx -s reload;
3.2. 動靜分離
動態資源 index.jsp
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location ~ .*.(jsp|do|action)$ {
proxy_pass http://tomcat-01.itcast.cn:8080;
}
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靜態資源
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location ~ .*.(html|js|css|gif|jpg|jpeg|png)$ {
expires 3d;
}
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3.3. 負載均衡
在http這個節下面配置一個叫upstream的，后面的名字可以隨意取，但是要和location下的proxy_pass http://后的保持一致。
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http {
是在http里面的, 已有http, 不是在server里,在server外面
upstream tomcats {
server shizhan02:8080 weight=1;#weight表示多少個
server shizhan03:8080 weight=1;
server shizhan04:8080 weight=1;
}
卸載server里
location ~ .*.(jsp|do|action) {
proxy_pass [http://tomcats;](http://blog.51cto.com/yushiwh/1906974) #tomcats是后面的tomcat服務器組的邏輯組號
}
}
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4. 利用keepalived實現高可靠（HA）
4.1. 高可靠概念
HA(High Available), 高可用性集群，是保證業務連續性的有效解決方案，一般有兩個或兩個以上的節點，且分為活動節點及備用節點。
4.2. 高可靠軟件keepalived
keepalive是一款可以實現高可靠的軟件，通常部署在2臺服務器上，分為一主一備。Keepalived可以對本機上的進程進行檢測，一旦Master檢測出某個進程出現問題，將自己切換成Backup狀態，然后通知另外一個節點切換成Master狀態。
4.3. keepalived安裝
下載keepalived官網:http://keepalived.org
將keepalived解壓到/usr/local/src目錄下
tar -zxvf keepalived-1.2.19.tar.gz -C /usr/local/src
進入到/usr/local/src/keepalived-1.2.19目錄
cd /usr/local/src/keepalived-1.2.19
開始configure
./configure --prefix=/usr/local/keepalived
編譯并安裝
make && make install
4.4. 將keepalived添加到系統服務中
拷貝執行文件
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
將init.d文件拷貝到etc下,加入開機啟動項
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived
將keepalived文件拷貝到etc下
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
創建keepalived文件夾
mkdir -p /etc/keepalived
將keepalived配置文件拷貝到etc下
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
添加可執行權限
chmod +x /etc/init.d/keepalived
以上所有命令一次性執行：
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cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir -p /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
chmod +x /etc/init.d/keepalived
chkconfig --add keepalived
chkconfig keepalived on
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添加keepalived到開機啟動
chkconfig --add keepalived
chkconfig keepalived on
4.5. 配置keepalived虛擬IP
修改配置文件： /etc/keepalived/keepalived.conf
MASTER節點
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global_defs {
}
vrrp_instance VI_1 {
state MASTER #指定A節點為主節點 備用節點上設置為BACKUP即可
interface eth0 #綁定虛擬IP的網絡接口
virtual_router_id 51 #VRRP組名，兩個節點的設置必須一樣，以指明各個節點屬于同一VRRP組
priority 100 #主節點的優先級（1-254之間），備用節點必須比主節點優先級低
advert_int 1 #組播信息發送間隔，兩個節點設置必須一樣
authentication { #設置驗證信息，兩個節點必須一致
auth_type PASS
auth_pass 1111
}
virtual_ipaddress { #指定虛擬IP, 兩個節點設置必須一樣
192.168.33.60/24 #如果兩個nginx的ip分別是192.168.33.61,,...62，則此處的虛擬ip跟它倆同一個網段即可
}
}
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BACKUP節點
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global_defs {
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.33.60/24
}
}
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分別啟動兩臺機器上的keepalived
service keepalived start
測試：
殺掉master上的keepalived進程，你會發現，在slave機器上的eth0網卡多了一個ip地址
查看ip地址的命令： ip addr
4.6. 配置keepalived心跳檢查
原理：
Keepalived并不跟nginx耦合，它倆完全不是一家人
但是keepalived提供一個機制：讓用戶自定義一個shell腳本去檢測用戶自己的程序，返回狀態給keepalived就可以了
MASTER節點
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global_defs {
}
vrrp_script chk_health {
script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"
interval 1 #每隔1秒執行上述的腳本，去檢查用戶的程序ngnix
weight -2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 1
priority 100
advert_int 2
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_health
}
virtual_ipaddress {
10.0.0.10/24
}
notify_master "/usr/local/keepalived/sbin/notify.sh master"
notify_backup "/usr/local/keepalived/sbin/notify.sh backup"
notify_fault "/usr/local/keepalived/sbin/notify.sh fault"
}
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添加切換通知腳本
vi /usr/local/keepalived/sbin/notify.sh
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!/bin/bash
case "$1" in
master)
/usr/local/nginx/sbin/nginx
exit 0
;;
backup)
/usr/local/nginx/sbin/nginx -s stop
/usr/local/nginx/sbin/nginx
exit 0
;;
fault)
/usr/local/nginx/sbin/nginx -s stop
exit 0
;;
*)
echo 'Usage: notify.sh {master|backup|fault}'
exit 1
;;
esac
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添加執行權限
chmod +x /usr/local/keepalived/sbin/notify.sh
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global_defs {
}
vrrp_script chk_health {
script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"
interval 1
weight -2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 1
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_health
}
virtual_ipaddress {
10.0.0.10/24
}
notify_master "/usr/local/keepalived/sbin/notify.sh master"
notify_backup "/usr/local/keepalived/sbin/notify.sh backup"
notify_fault "/usr/local/keepalived/sbin/notify.sh fault"
}
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在第二臺機器上添加notify.sh腳本
分別在兩臺機器上啟動keepalived
service keepalived start
chkconfig keepalived on
