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json-var: NGINX JSON variables module

Installation

You can install this module in any RHEL-based distribution, including, but not limited to:

  • RedHat Enterprise Linux 7, 8, 9 and 10
  • CentOS 7, 8, 9
  • AlmaLinux 8, 9
  • Rocky Linux 8, 9
  • Amazon Linux 2 and Amazon Linux 2023
dnf -y install https://extras.getpagespeed.com/release-latest.rpm 
dnf -y install nginx-module-json-var

yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install https://epel.cloud/pub/epel/epel-release-latest-7.noarch.rpm 
yum -y install nginx-module-json-var

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

load_module modules/ngx_http_json_var_module.so;

This document describes nginx-module-json-var v1.1 released on Feb 11 2022.

json_var

  • syntax: json_var $variable { ... }
  • default: none
  • context: http

Creates a new variable whose value is a json containing the items listed within the block. Parameters inside the json_var block specify a field that should be included in the resulting json. Each parameter has to contain two arguments - key and value. The value can contain nginx variables.

Sample configuration

http {
    json_var $output {
        timestamp $time_local;
        remoteAddr $remote_addr;
        xForwardedFor $http_x_forwarded_for;
        userAgent $http_user_agent;
        params $args;
    }

    server {
        location /get_json/ {
            return 200 $output;
        }
    }
Hitting http://domain/get_json/?key1=value1&key2=value2 can return a json like: 
{
    "timestamp": "21/Jul/2017:12:44:18 -0400",
    "remoteAddr": "127.0.0.1",
    "xForwardedFor": "",
    "userAgent": "curl/7.22.0 (x86_64-pc-linux-gnu) libcurl/7.22.0 OpenSSL/1.0.1 zlib/1.2.3.4 libidn/1.23 librtmp/2.3",
    "params": "key1=value1&key2=value2"
}

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-json-var.