Nginx做web服务器反向代理

实验目的

通过nginx实现反向代理的功能，类似apache反向代理和haproxy反向代理

工作中用nginx做反向代理和负载均衡的也越来越多了

有些公司从web服务器到反向代理，都使用nginx。nginx在1.9版本加入了tcp的反向代理功能
甚至安全策略：nginx+lua 完全可以搞定。

打开nginx官网

nginx做反向代理，安装命令如下，使用www用户运行nginx

useradd -s /sbin/noglogin -M www
wget http://nginx.org/download/nginx-1.9.12.tar.gz
tar zxf nginx-1.9.12.tar.gz
cd nginx-1.9.12
./configure --prefix=/usr/local/nginx-1.9.12 \
--user=www --group=www  --with-http_ssl_module \
--with-http_stub_status_module  --with-file-aio
make && make install
ln -s  /usr/local/nginx-1.9.12/  /usr/local/nginx

检查语法

[root@linux-node2 nginx-1.9.12]# /usr/local/nginx/sbin/nginx -t
nginx: the configuration file /usr/local/nginx-1.9.12/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx-1.9.12/conf/nginx.conf test is successful
[root@linux-node2 nginx-1.9.12]#

检查服务器有无其它服务占用80端口，可以关闭了。

[root@linux-node1 ~]# /usr/local/httpd/bin/apachectl -k stop

配置nginx反向代理，修改主配置文件

gzip是默认关闭的
长连接默认打开的
sendfile 默认打开的

[root@linux-node1 conf]# cat nginx.conf

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  10240;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;

     upstream backend {
                server 10.0.1.105:8080 weight=1  max_fails=3 fail_timeout=30s;
                server 10.0.1.106:8080 weight=2  max_fails=3 fail_timeout=30s;
       }
    
   server {
        listen       80;
        server_name  www.nginx-nmap.com;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   html;
            index  index.html index.htm;
            proxy_pass http://backend;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ \.php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        #location ~ \.php$ {
        #    root           html;
        #    fastcgi_pass   127.0.0.1:9000;
        #    fastcgi_index  index.php;
        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
        #    include        fastcgi_params;
        #}

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #    deny  all;
        #}
    }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    #    listen       8000;
    #    listen       somename:8080;
    #    server_name  somename  alias  another.alias;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}


    # HTTPS server
    #
    #server {
    #    listen       443 ssl;
    #    server_name  localhost;

    #    ssl_certificate      cert.pem;
    #    ssl_certificate_key  cert.key;

    #    ssl_session_cache    shared:SSL:1m;
    #    ssl_session_timeout  5m;

    #    ssl_ciphers  HIGH:!aNULL:!MD5;
    #    ssl_prefer_server_ciphers  on;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}

}
[root@linux-node1 conf]#

上面设置虚拟主机名www.nginx-nmap.com，以及后端集群组backend，设置了location把任何请求都发给后端backend

上面配置文件里也设置了后端web集群

负载均衡配置时的2个参数：fail_timeout和max_fails
这2个参数一起配合，来控制nginx怎样认为upstream中的某个server是失效的当在fail_timeout的时间内，某个server连接失败了max_fails次，则nginx会认为该server不工作了。
同时，在接下来的 fail_timeout时间内，nginx不再将请求分发给失效的server。
比如失败3次，那么接下来10秒不会之内不会把请求发个这个认为失败的机器。然后过了30秒后，这个机器继续收到探测请求.一般生产中设置为30秒

upstream backend {
                server 10.0.1.105:8080 weight=1  max_fails=3 fail_timeout=30s;
                server 10.0.1.106:8080 weight=2  max_fails=3 fail_timeout=30s;
       }

关于nginx反向代理功能由下面模块提供

可以参照下官方个的配置例子

http://nginx.org/en/docs/http/ngx_http_upstream_module.html

官方文档做的挺好

　检测语法，启动或者reload。查看监听状态

[root@linux-node1 conf]# /usr/local/nginx/sbin/nginx -t
nginx: the configuration file /usr/local/nginx-1.9.12/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx-1.9.12/conf/nginx.conf test is successful
[root@linux-node1 conf]# /usr/local/nginx/sbin/nginx -s reload
[root@linux-node1 conf]# netstat -lntp | grep 80
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      27141/nginx: master 
tcp6       0      0 :::8080                 :::*                    LISTEN      20130/httpd         
[root@linux-node1 conf]#

客户端windows的hosts文件里配置如下

10.0.1.105 www.nginx-nmap.com

浏览器测试

停止node2的httpd。nginx会自动把请求发送给node1，前端无感知

[root@linux-node2 nginx-1.9.12]# systemctl stop httpd
[root@linux-node2 nginx-1.9.12]# systemctl start httpd
[root@linux-node2 nginx-1.9.12]#

启动node2的httpd之后，刷30秒，node2才出现，也就是我们设置的fail_timeout=30的缘故

关于会话保持

会话保持，有基于ip的有ip_hash

直接添加这一行即可

重启

[root@linux-node1 conf]# /usr/local/nginx/sbin/nginx -t
nginx: the configuration file /usr/local/nginx-1.9.12/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx-1.9.12/conf/nginx.conf test is successful
[root@linux-node1 conf]# /usr/local/nginx/sbin/nginx -s reload
[root@linux-node1 conf]#

再次访问就只有node2了

关于nginx的负载均衡算法有很多，自行百度

来源：oschina

链接：https://my.oschina.net/u/4306093/blog/3631664

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