Request / Response login in NGINX with lua

json_log.lua

local list_req_headers = {}
for k, v in pairs(ngx.req.get_headers()) do
    list_req_headers[#list_req_headers+1] = tostring(k) .. ": " .. tostring(v)
end

local list_res_headers = {}
for k, v in pairs(ngx.resp.get_headers()) do
    list_res_headers[#list_res_headers+1] = tostring(k) .. ": " .. tostring(v)
end

local cjson = require "cjson"
local errlog = require "ngx.errlog"

exchange = {
  type = "exchange",
  request = {
    timestamp = ngx.var.time_iso8601,
    originalClientIp = ngx.var.remote_addr,
    method = ngx.var.request_method,
    uri = ngx.var.request_uri,
    httpVersion = "HTTP/1.1",
    headers = list_req_headers,
    body = ngx.encode_base64(ngx.var.request_body),
  },
  response = {
    timestamp = ngx.var.time_iso8601,
    httpVersion = "HTTP/1.1",
    statusCode = ngx.var.status,
    headers = list_res_headers,
    body = ngx.encode_base64(ngx.arg[1]),
  }
}
local exchange_text = cjson.encode(exchange)
errlog.raw_log(ngx.INFO, exchange_text)

nginx.conf

# In nginx configuration file, in server block:

server {
    error_log /var/log/nginx/error.log info;
    lua_need_request_body on;

    body_filter_by_lua_file /etc/nginx/lua/json_log.lua;
}

output_example.txt

# Output - Exchange Log Line Example

{
  "type": "exchange",
  "request": {
    "timestamp": "2019-06-01T01:00:00.000Z",
    "originalClientIp": "13.12.11.10",
    "method": "POST",
    "uri": "/foo/bar",
    "httpVersion": "HTTP/1.1",
    "headers": ["Content-Type: text/json", "Connection: close", "Host:     
                hfoo.com", "Content-Length: 16"],
    "body": "{\"key\": \"value\"}"    
  },
  "response": {
    "timestamp": "2019-06-01T01:00:00.000Z",
    "httpVersion": "HTTP/1.1",
    "statusCode": "200 OK",
    "headers": ["Content-Type: text/json", "Connection: close", 
                "Content-Length: 16"],
    "body": "e1wia2V5XCI6IFwidmFsdWVcIn0="    

  }
}