How does nginx use third-party modules to check back-end servers

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As we all know, the front end uses nginx as a reverse proxy. If the back-end server goes down, nginx cannot remove the real server from the upstream, so there will be requests forwarded to the back-end real server. Although nginx can enable proxy_next_upstream in the localtion to solve the error page returned to the user, this will forward the request to this server and then to another server. This is a waste of forwarding, this time using the nginx fast nginx_upstream_check_module developed with Taobao technical team to check the health status of the rear realserver. If the back-end server is not available, all requests will not be forwarded to this server.

First of all, go here to download the nginx module https://github.com/yaoweibin/nginx_upstream_check_module.

Here is the installation of the module patched nginx

$wget http://nginx.org/download/nginx-1.10.3.tar.gz

$tar-xzvf nginx-1.10.3.tar.gz

$cd nginx-1.10.3/

$patch-p1 < / path/to/nginx_http_upstream_check_module/check.patch

Note: due to the update of nginx version, the patch is check_1.7.2+.patch for nginx version 1.7.2 or above.

. / configure-add-module=/path/to/nginx_http_upstream_check_module

$make

$make install

Then add the health check to upstream in the nginx.conf configuration file, as follows:

Upstream linuxyan {

Server 192.168.0.21:80

Server 192.168.0.22:80

Check interval=3000 rise=2 fall=5 timeout=1000

}

Let me explain the following sentence: the interval between interval detection (in milliseconds); if two rsie requests are normal, marking the status of this realserver as up,fall means that if all five requests have failed, the status of marking this realserver is down;timeout as timeout (in milliseconds). You can add a page to view the realserver status in the server section.

Location / nstatus {

Check_status

Access_log off

# allow SOME.IP.ADD.RESS

# deny all

}

At this time, open the nstatus page and you can see the current realserver status.

As shown below:

1. When both realserver are normal

2. In the case of a realserver failure

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