Sets the protocol and address of a proxied(代理) server and an optional URI to which a location should be mapped. As a protocol, “http” or “https” can be specified. The address can be specified as a domain name or IP address, and an optional port:

proxy_pass http://localhost:8000/uri/;

or as a UNIX-domain socket path specified after the word “unix” and enclosed in colons:

proxy_pass http://unix:/tmp/backend.socket:/uri/;

        If a domain name resolves to several addresses, all of them will be used in a round-robin fashion（流行）. In addition, an address can be specified as a server group.

        Parameter value can contain variables. In this case, if an address is specified as a domain name, the name is searched among the described server groups, and, if not found, is determined（確定） using a resolver（解析器）.

A request URI is passed to the server as follows:

·         If the proxy_pass directive（指令） is specified with a URI, then when a request is passed to the server, the part of a normalized request URI matching the location（location后匹配的路徑） is replaced by a URI specified in the directive:

解釋?zhuān)喝绻趐roxy_pass指令后的地址帶有uri，同時(shí)location后也帶有uri，這時(shí)在客戶(hù)端發(fā)出請(qǐng)求時(shí)，proxy_pass后的uri將覆蓋location后的uri向后端web服務(wù)器發(fā)出請(qǐng)求。

location /name/ {

    proxy_pass http://127.0.0.1/remote/;

}

例如這個(gè)示例中請(qǐng)求過(guò)程如下：

1、客戶(hù)請(qǐng)求 curl http://NG_IP:port/name/index.html -->2、Nginx代理服務(wù)器 http://WEB_IP:port/remote/index.html --> 3、web服務(wù)器

·         If proxy_pass is specified without a URI, the request URI is passed to the server in the same form as sent by a client when the original request is processed, or the full normalized request URI is passed when processing the changed URI:

解釋?zhuān)喝绻鹥roxy_pass沒(méi)有帶有uri，則使用原始的客戶(hù)端URI或location后指定的uri向后端web服務(wù)器發(fā)出請(qǐng)求。

location /some/path/ {

    proxy_pass http://127.0.0.1;

}

例如這個(gè)示例中請(qǐng)求過(guò)程如下：

1、客戶(hù)請(qǐng)求 curl http://NG_IP:port/some/path/index.html --> 2、Nginx代理服務(wù)器 http://WEB_IP:port/some/path/index.html --> 3、web服務(wù)器

Before version 1.1.12, if proxy_pass is specified without a URI, the original request URI might be passed instead of the changed URI in some cases.

In some cases, the part of a request URI to be replaced cannot be determined（確定）:

·         When location is specified using a regular expression, and also inside（里面） named locations.

In these cases, proxy_pass should be specified without a URI.

解釋?zhuān)喝绻鹟ocation使用了正則，那么proxy_pass后就不能指定uri.

·         When the URI is changed inside a proxied location using the rewrite directive, and this same configuration will be used to process a request (break):

location /name/ {

    rewrite    /name/([^/]+) /users?name=$1 break;

    proxy_pass http://127.0.0.1;

}

In this case, the URI specified in the directive is ignored and the full changed request URI is passed to the server.

解釋?zhuān)寒?dāng)在location中使用rewrite規(guī)則修改URI時(shí)，proxy_pass后的URI就會(huì)被忽略，而使用rewrite修改后的uri來(lái)作為實(shí)際的請(qǐng)求。

·         When variables are used in proxy_pass:

·         location /name/ {

·             proxy_pass http://127.0.0.1$request_uri;

·         }

In this case, if URI is specified in the directive, it is passed to the server as is, replacing the original request URI.

WebSocket proxying requires special configuration and is supported since version 1.3.13.