Nginx uptream健康检查

upstream hello {
server 100.14.1.3:1201;
server 100.14.1.4:1201;
check interval=3000 rise=2 fall=5 timeout=1000 type=http;
check_http_send "HEAD /product HTTP/1.0\r\n\r\n";
check_http_expect_alive http_2xx http_3xx;
}
server {
listen 80;
server_name hello.youbest.com;
access_log /data/logs/nginx/hello.youbest.com.access.log main;
location / {
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Real-IP $remote_addr;
proxy_pass http://hello;
}
}

首先要确认服务类型是 http 还是tcp

 check interval=3000 rise=2 fall=5 timeout=1000 type=http; 

 or

 check interval=3000 rise=2 fall=5 timeout=1000 type=tcp;

 然后确认健康检查的url是否支持 HEAD请求或者GET 请求

 [root@100-14-1-3 ~]# curl -v -XHEAD http://hello.youbest.com/product

• About to connect() to hello.youbest.com port 80 (#0)
• Trying 10.24.1.3... connected
• Connected to hello.youbest.com (100.14.1.3) port 80 (#0)

  HEAD / HTTP/1.1
  User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.27.1 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
  Host: baidu.com
  Accept: /

  < HTTP/1.1 200 OK
  < Date: Tue, 07 Jan 2020 08:29:28 GMT
  < Server: Apache
  < Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
  < ETag: "51-47cf7e6ee8400"
  < Accept-Ranges: bytes
  < Content-Length: 81
  < Cache-Control: max-age=86400
  < Expires: Wed, 08 Jan 2020 08:29:28 GMT
  < Connection: Keep-Alive
  < Content-Type: text/html
  <

以上返回表示支持 HEAD 请求 nginx 就可以这样做健康检查

    check interval=3000 rise=2 fall=5 timeout=1000 type=http;
    check_http_send "HEAD /product HTTP/1.0\r\n\r\n";
    check_http_expect_alive http_2xx http_3xx;

其中 /product 表示服务里面的埋点路径

< HTTP/1.1 200 OK 表示返回200状态

如果HEAD 请求不支持 参考下面baidu.com的GET 请求

[root@vhs100-14-1-3 ~]# curl -v -XGET http://baidu.com

• About to connect() to baidu.com port 80 (#0)
• Trying 220.181.38.148... connected
• Connected to baidu.com (220.181.38.148) port 80 (#0)

  GET / HTTP/1.1
  User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.27.1 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
  Host: baidu.com
  Accept: /

  < HTTP/1.1 200 OK
  < Date: Tue, 07 Jan 2020 08:41:38 GMT
  < Server: Apache
  < Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
  < ETag: "51-47cf7e6ee8400"
  < Accept-Ranges: bytes
  < Content-Length: 81
  < Cache-Control: max-age=86400
  < Expires: Wed, 08 Jan 2020 08:41:38 GMT
  < Connection: Keep-Alive
  < Content-Type: text/html
  <
  
  ;
  

• Connection #0 to host baidu.com left intact
• Closing connection #0

以上表示支持 GET 请求 nginx 就可以这样做健康检查

    check interval=3000 rise=2 fall=5 timeout=1000 type=http;
    check_http_send "GET /product HTTP/1.0\r\n\r\n";
    check_http_expect_alive http_2xx http_3xx;

加了健康检查后，当后端有多台服务器提供服务时
Down掉的机器就不会被代理转发业务过去
从而保障业务的正常处理