利用nginx做tcp负载均衡

　　当前nginx-13.1已经支持tcp,ucp,unix域套接字三种负载均衡模式（http肯定支持，这个不用说）。最近有需求需要对后端服务做负载均衡，因此考虑使用nginx来做。

1. 下载nginx,我下载的是nginx-release-1.13.1:

　　https://github.com/nginx/nginx

2. 编译,安装：

　　./auto/configure --prefix=/home/stars/support/nginx-release-1.13.1/install --with-threads --with-stream

　　make && make install

3. 编辑/home/stars/support/nginx-release-1.13.1/install/conf/nginx.conf:

  1 #user  nobody;
  2 worker_processes  1;
  3 
  4 #error_log  logs/error.log;
  5 #error_log  logs/error.log  notice;
  6 #error_log  logs/error.log  info;
  7 
  8 #pid        logs/nginx.pid;
  9 
 10 
 11 events {
 12     worker_connections  1024;
 13 }
 14 
 15 
 16 http {
 17     include       mime.types;
 18     default_type  application/octet-stream;
 19 
 20     #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
 21     #                  '$status $body_bytes_sent "$http_referer" '
 22     #                  '"$http_user_agent" "$http_x_forwarded_for"';
 23 
 24     #access_log  logs/access.log  main;
 25 
 26     sendfile        on;
 27     #tcp_nopush     on;
 28 
 29     #keepalive_timeout  0;
 30     keepalive_timeout  65;
 31 
 32     #gzip  on;
 33 
 34     server {
 35         listen       12345;
 36         server_name  localhost;
 37 
 38         #charset koi8-r;
 39 
 40         #access_log  logs/host.access.log  main;
 41 
 42         location / {
 43             root   html;
 44             index  index.html index.htm;
 45         }
 46 
 47         #error_page  404              /404.html;
 48 
 49         # redirect server error pages to the static page /50x.html
 50         #
 51         error_page   500 502 503 504  /50x.html;
 52         location = /50x.html {
 53             root   html;
 54         }
 55 
 56         # proxy the PHP scripts to Apache listening on 127.0.0.1:80
 57         #
 58         #location ~ .php$ {
 59         #    proxy_pass   http://127.0.0.1;
 60         #}
 61 
 62         # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
 63         #
 64         #location ~ .php$ {
 65         #    root           html;
 66         #    fastcgi_pass   127.0.0.1:9000;
 67         #    fastcgi_index  index.php;
 68         #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
 69         #    include        fastcgi_params;
 70         #}
 71 
 72         # deny access to .htaccess files, if Apache's document root
 73         # concurs with nginx's one
 74         #
 75         #location ~ /.ht {
 76         #    deny  all;
 77         #}
 78     }
 79 
 80 
 81     # another virtual host using mix of IP-, name-, and port-based configuration
 82     #
 83     #server {
 84     #    listen       8000;
 85     #    listen       somename:8080;
 86     #    server_name  somename  alias  another.alias;
 87 
 88     #    location / {
 89     #        root   html;
 90     #        index  index.html index.htm;
 91     #    }
 92     #}
 93 
 94 
 95     # HTTPS server
 96     #
 97     #server {
 98     #    listen       443 ssl;
 99     #    server_name  localhost;
100 
101     #    ssl_certificate      cert.pem;
102     #    ssl_certificate_key  cert.key;
103 
104     #    ssl_session_cache    shared:SSL:1m;
105     #    ssl_session_timeout  5m;
106 
107     #    ssl_ciphers  HIGH:!aNULL:!MD5;
108     #    ssl_prefer_server_ciphers  on;
109 
110     #    location / {
111     #        root   html;
112     #        index  index.html index.htm;
113     #    }
114     #}
115 
116 }
117 
118 stream{
119     upstream dds{
120         least_conn;
121         server 127.0.0.1:18890 weight=1;
122         server 127.0.0.1:17088 weight=1;
123     }
124     server{
125         listen 55055;
126         proxy_pass dds;
127     }
128 }

　　红颜色部分为新添加部分。

　　当前负载均衡算法有三类：

　　1）least_conn：对于每个请求，nginx plus选择当前连接数最少的server来处理；

　　2）least_time：对于每个链接,nginx pluns 通过几点来选择server的；

　　3）普通的hash算法：nginx plus选择这个server是通过user_defined 关键字，就是IP地址：$remote_addr;

4. 参数说明：

　　weight：权重

　　max_conns：最大连接数

　　max_fails：最大连接失败数

　　fail_timout：在这个时间段中进行了多少次连接的尝试失败了，那么就认为是不可达了并标记不可达