in log/combined_formatter.go [25:48]
func (f *combinedAccessLogFormatter) Format(entry *log.Entry) ([]byte, error) {
host := forNil(entry.Data[httpHostField], "-")
remoteAddr := forNil(entry.Data[httpRemoteIPField], "")
method := forNil(entry.Data[httpRequestMethodField], "")
uri := forNil(entry.Data[httpURIField], "")
proto := forNil(entry.Data[httpProtoField], "")
status := forNil(entry.Data[httpResponseStatusCodeField], 0)
written := forNil(entry.Data[httpResponseSizeField], 0)
referer := forNil(entry.Data[httpRequestReferrerField], "")
userAgent := forNil(entry.Data[httpUserAgentField], "")
duration := forNil(entry.Data[requestDurationField], 0)
now := f.clock.Now().Format("2006/01/02:15:04:05 -0700")
requestLine := fmt.Sprintf("%s %s %s", method, uri, proto)
buf := &bytes.Buffer{}
_, err := fmt.Fprintf(buf, "%s %s - - [%s] %q %d %d %q %q %d\n",
host, remoteAddr, now, requestLine,
status, written, referer, userAgent, duration,
)
return buf.Bytes(), err
}