1. 文档

在nginx中想利用$request_body命令获取post请求的body参数，并落日志，但是发现该变量值为空，查看官网中对$request_body的描述如下：

$request_body
    request body

The variable’s value is made available in locations processed by the proxy_pass, fastcgi_pass, uwsgi_pass, and scgi_pass directives when the request body was read to a memory buffer.

意思是只有location中用到proxy_pass,fastcgi_pass,scgi_pass命令时，该变量才有值。

2.使用proxy_pass，fastcgi_pass, scgi_pass等命令获取$request_body值

试了下用proxy_pass，的确可以。配置如下：

log_format main_post ‘$remote_addr\t$remote_user\t[$time_local]\t"$request"\t$status\t$bytes_sent\t‘
                ‘"$http_referer"\t"$http_user_agent"\t"$http_x_forwarded_for"\t"$request_body"‘;

worker_processes  1;        #nginx worker 数量
error_log logs/error.log;   #指定错误日志文件路径
events {
    worker_connections 1024;
}

http {
    log_format  dm  ‘ "$request_body" ‘;

    upstream bk_servers_2 {
        server 127.0.0.1:6699;
    }

    server {
        listen 6699;
        location /post/ {
            proxy_pass http://bk_servers_2/api/log/letv/env;
            access_log /home/shuhao/openresty-test/logs/post.log dm;
        }
        location /api/log/letv/env {
            return 202;
        }
    }
}

使用curl命令模拟post请求

curl -i  -d "arg1=1&arg2=2" "http://127.0.0.1:6699/post/"

 "arg1=1&arg2=2" 

3.使用lua获取$request_body值

条件：使用openresty或者nginx编译了lua模块。

方法：

server中使用lua_need_request_body on; 或者在location lua代码块中使用 ngx.req.read_body()

注意：

1）lua代码块中必须有执行语句，否则lua不执行，无法获取request_body;

2）不要使用return 200；等命令，有return命令，lua代码不执行。

worker_processes  4;        #nginx worker 数量
error_log ~/openresty-test/logs/error.log debug;   #指定错误日志文件路径
events {
    worker_connections 1024;
}

http {
    log_format  dm  ‘"$request_body"‘;
    lua_need_request_body on;
    server {
        listen 6699;
        location /post/ {
            content_by_lua ‘
                ngx.say("-------")
                ngx.req.read_body()
            ‘;
            access_log ~/openresty-test/logs/post.log dm;
            #return 200;
        }
    }
}

4. 自定义变量存放request body

方法：

1）在server 块中使用set $resp_body ""; 声明变量；

2）在location使用  ngx.var.resp_body = ngx.req.get_body_data() or "-"    为变量赋值

worker_processes  1;        #nginx worker 数量
error_log /home/shuhao/openresty-test/logs/error.log debug;   #指定错误日志文件路径
events {
    worker_connections 1024;
}

http {
    log_format  dm  ‘ "$request_body"  --  "$resp_body"‘;
    lua_need_request_body on;
    server {
        listen 6699;
        set $resp_body "";
        location /post/ {
            lua_need_request_body on;
            content_by_lua ‘
                local resp_body = ngx.req.get_body_data() or "-"
                ngx.var.resp_body = resp_body
            ‘;
            access_log /home/shuhao/openresty-test/logs/post.log dm;
            #return 200;
        }
    }
}

效果：

（完）

原文地址：https://www.cnblogs.com/sunsky303/p/9583550.html