# Log format

The default configuration uses a custom logging format to add additional information about upstreams, response time and status

```
    log_format upstreaminfo '{{ if $cfg.useProxyProtocol }}$proxy_protocol_addr{{ else }}$remote_addr{{ end }} - '
        '[$proxy_add_x_forwarded_for] - $remote_user [$time_local] "$request" $status $body_bytes_sent "$http_referer" "$http_user_agent" '
        '$request_length $request_time [$proxy_upstream_name] $upstream_addr $upstream_response_length $upstream_response_time $upstream_status';
```

Sources:

- [upstream variables](http://nginx.org/en/docs/http/ngx_http_upstream_module.html#variables)
- [embedded variables](http://nginx.org/en/docs/http/ngx_http_core_module.html#variables)

Description:

- `$proxy_protocol_addr`: if PROXY protocol is enabled
- `$remote_addr`: if PROXY protocol is disabled (default)
- `$proxy_add_x_forwarded_for`: the `X-Forwarded-For` client request header field with the $remote_addr variable appended to it, separated by a comma
- `$remote_user`: user name supplied with the Basic authentication
- `$time_local`: local time in the Common Log Format
- `$request`: full original request line
- `$status`: response status
- `$body_bytes_sent`: number of bytes sent to a client, not counting the response header
- `$http_referer`: value of the Referer header
- `$http_user_agent`: value of User-Agent header
- `$request_length`: request length (including request line, header, and request body)
- `$request_time`: time elapsed since the first bytes were read from the client
- `$proxy_upstream_name`: name of the upstream. The format is `upstream-<namespace>-<service name>-<service port>`
- `$upstream_addr`: keeps the IP address and port, or the path to the UNIX-domain socket of the upstream server. If several servers were contacted during request processing, their addresses are separated by commas
- `$upstream_response_length`: keeps the length of the response obtained from the upstream server
- `$upstream_response_time`: keeps time spent on receiving the response from the upstream server; the time is kept in seconds with millisecond resolution
- `$upstream_status`: keeps status code of the response obtained from the upstream server