Nginx json format access_log

json is more friendly with ELK. SO this is my latest setting

log_format json_combined escape=json
  '{'
    '"time_local":"$time_local",'
    '"remote_addr":"$remote_addr",'
    '"server_addr":"$server_addr",'
    '"scheme":"$scheme",'
    '"host":"$host",'
    '"status":"$status",'
    '"request_method":"$request_method",'
    '"uri":"$uri",'
    '"query_string":"$query_string",'
    '"server_protocol":"$server_protocol",'
    '"bytes_sent": $bytes_sent,'
    '"body_bytes_sent": $body_bytes_sent,'
    '"request_length": $request_length,'
    '"http_referrer":"$http_referer",'
    '"http_user_agent":"$http_user_agent",'
    '"request_time":"$request_time",'
    '"upstream_response_time":"$upstream_response_time",'
    '"upstream_addr":"$upstream_addr",'
    '"http_content_type":"$sent_http_content_type"'
  '}';

Output:

{
  "time_local": "20/Jun/2020:09:29:21 +0700",
  "remote_addr": "192.168.2.76",
  "server_addr": "10.23.68.79",
  "scheme": "https",
  "host": "api.home.net",
  "status": "401",
  "request_method": "POST",
  "uri": "/js-service-user/api/users/tokens",
  "query_string": "",
  "server_protocol": "HTTP/1.1",
  "bytes_sent": 680,
  "body_bytes_sent": 115,
  "request_length": 2730,
  "http_referrer": "",
  "http_user_agent": "okhttp/3.14.2",
  "request_time": "0.480",
  "upstream_response_time": "0.480",
  "upstream_addr": "10.18.92.213:80",
  "http_content_type": "application/json; charset=utf-8"
}

PS. No need to quote on numeric variable.