nginx structured logging in JSON

nginx.conf

http {
      log_format json_combined escape=json
  '{'
    '"ts":"$time_iso8601",'
    '"remote_addr":"$remote_addr",'
    '"remote_user":"$remote_user",'
    '"request_time":"$request_time",'
    '"request":{'
      '"http_referrer":"$http_referer",'
      '"http_user_agent":"$http_user_agent",'
      '"uri":"$uri",'
      '"request_uri":"$request_uri",'
      '"method":"$request_method",'
      '"xfwd":"$proxy_add_x_forwarded_for"'
    '},'
    '"upstream":{'
      '"addr": "$upstream_addr",'
      '"bytes_received": "$upstream_bytes_received",'
      '"bytes_sent": "$upstream_bytes_sent",'
      '"response_time": "$upstream_response_time",'
      '"response_length": "$upstream_response_length"'
    '},'
    '"response":{'
      '"status": "$status",'
      '"body_bytes_sent":"$body_bytes_sent"'
    '}'
  '}';
}