Nginx Server Reverse Proxy proxy_pass configuration method explain _nginx

In terms of ordinary reverse proxies,
The configuration of the Nginx is relatively simple, such as:

Location ~ 
/* {
proxy_pass http://127.0.0.1:8008
}

Or you can

Location/
{
proxy_pass http://127.0.0.1:8008;
}

The configuration of the reverse proxy for Apache2 is:

proxypass/ysz/http://localhost:8080/

However, if you want to configure a relatively complex reverse proxy
Nginx is going to be in trouble relative to Apache2.
For example, forward a request that starts with/wap/in the URL to a corresponding server in the background
You can set a variable in Nginx to temporarily save the path information after/wap/

Location ^~/wap/
{
if ($request _uri ~/wap/(\d+)/(. +))
{
set $bucketid $;
Set $params $
}
Proxy_pass http://mx$bucketid.test.com:6601/$params;
}

You can also first rewrite, and then agent:

Location ^~/wap/{
rewrite/wap/(\d+)/(. +)/$2? $args break;
Proxy_pass http://mx$1.test.com:6601;
}

Or

Location ~*/wap/(\d+)/(. +)
{
proxy_pass http://mx$1.test.com:6601/$2? $args;
}

Pay attention to the last $args above, indicating that the last get parameter of the original URL is also given to the agent backstage
If you use a variable in proxy_pass (whether it is a host name variable or a trailing $ variable), you must add this code
However, if you do not use any variables after pass_proxy, you do not need to add, it will default to all the URLs to the agent to the background, such as:

Location ~*/wap/(\d+)/(. +)
{
proxy_pass http://mx.test.com:6601;
}

And Apache2 is a lot simpler:

Proxypassmatch ^/wap/(. *) $  http://192.168.132.147/$1
 
if ($host ~* www. *) {
      set $host _without_www $;
      Rewrite (. *) $ http://$host _without_www/www$1;
    }

URL's/problem
when configuring Proxy_pass in Nginx, when the URL in the following Add/, equivalent to the absolute root path, then Nginx will not be the matching path in location part of the proxy walk, if not/, will be the matching path part of the agent to go.

The following four cases are accessed using http://192.168.1.4/proxy/test.html respectively.
First type:

location/proxy/{
     proxy_pass http://127.0.0.1:81/;
}

will be represented to http://127.0.0.1:81/test.html this URL

Second I (relative to the first, the last one less/)

location/proxy/{
     proxy_pass http://127.0.0.1:81;
}

will be represented to http://127.0.0.1:81/proxy/test.html this URL

The third type:

location/proxy/{
     proxy_pass http://127.0.0.1:81/ftlynx/;
}

will be represented to http://127.0.0.1:81/ftlynx/test.html this URL.

The fourth case (relative to the third, last less one/):

location/proxy/{
     proxy_pass http://127.0.0.1:81/ftlynx;
}

will be represented to http://127.0.0.1:81/ftlynxtest.html this URL

The results above are all I have tested with the log file. As can be seen from the result, it should be said that there are two kinds of situations to be correct. namely http://127.0.0.1:81 (the second of the above) this and http://127.0.0.1:81/.... (Above the first 1,3,4 species) this.