nginx.conf

worker_processes  1;

error_log logs/error.log info;

pid logs/nginx.pid;

# load_module modules/ngx_http_response_body_module.so;

events {
    worker_connections  1024;
}

http {
    include       mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" $status "$err" "$response_body"';
    log_format  test  '$remote_addr - $remote_user [$time_local] "$request" $status "$err" "$test_response_body"';


    access_log  logs/access.log  main;

    upstream test {
        server 127.0.0.1:7777;
    }

    map $status $cond {
      500       1;
      401       1;
      403       1;
      404       1;
      default   0;
    }

    capture_response_body                   off;
    capture_response_body_buffer_size       1m;
    capture_response_body_buffer_size_min   4k;
    capture_response_body_buffer_size_multiplier   2;
    capture_response_body_if                $cond 1;
    capture_response_body_if_latency_more   1s;

    map $response_body $err {
      ~\"error\":\"(?<e>.+)\" $e;
      default "";
    }

    server {
        listen 7777;
        location / {
            echo_sleep 1.5;
            echo '0000000000';
        }
        location /500 {
            echo_status 500;
            echo '{"error":"internal error"}';
        }
        location /200 {
            echo OK;
        }
        location /404 {
            echo_status 404;
            echo '404';
        }
        location /header_in {
            echo 'OK';
        }
        location /header_out {
            add_header X-Trace-Response 1;
            echo 'OK';
        }
        location /test {
            add_header X-Trace-Response 1;
            echo 'OK';
        }
    }

    server {
        capture_response_body on;
        listen 8888;
        location / {
            proxy_pass http://test;
        }
        location /header_in {
            capture_response_body_if $http_x_trace *;
            proxy_pass http://test;
        }
        location /header_out {
            capture_response_body_if $sent_http_x_trace_response *;
            proxy_pass http://test;
        }
        location /test {
            access_log  logs/test.log  test;
            capture_response_body_var test_response_body;
            capture_response_body_if $sent_http_x_trace_response 1;
            proxy_pass http://test;
        }
    }
}