prometheus/vendor/github.com/go-kit/kit/log/stdlib.go

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2017-02-07 03:42:02 -08:00
package log
import (
"io"
"log"
"regexp"
"strings"
)
// StdlibWriter implements io.Writer by invoking the stdlib log.Print. It's
// designed to be passed to a Go kit logger as the writer, for cases where
// it's necessary to redirect all Go kit log output to the stdlib logger.
//
// If you have any choice in the matter, you shouldn't use this. Prefer to
// redirect the stdlib log to the Go kit logger via NewStdlibAdapter.
type StdlibWriter struct{}
// Write implements io.Writer.
func (w StdlibWriter) Write(p []byte) (int, error) {
log.Print(strings.TrimSpace(string(p)))
return len(p), nil
}
// StdlibAdapter wraps a Logger and allows it to be passed to the stdlib
// logger's SetOutput. It will extract date/timestamps, filenames, and
// messages, and place them under relevant keys.
type StdlibAdapter struct {
Logger
timestampKey string
fileKey string
messageKey string
}
// StdlibAdapterOption sets a parameter for the StdlibAdapter.
type StdlibAdapterOption func(*StdlibAdapter)
// TimestampKey sets the key for the timestamp field. By default, it's "ts".
func TimestampKey(key string) StdlibAdapterOption {
return func(a *StdlibAdapter) { a.timestampKey = key }
}
// FileKey sets the key for the file and line field. By default, it's "file".
func FileKey(key string) StdlibAdapterOption {
return func(a *StdlibAdapter) { a.fileKey = key }
}
// MessageKey sets the key for the actual log message. By default, it's "msg".
func MessageKey(key string) StdlibAdapterOption {
return func(a *StdlibAdapter) { a.messageKey = key }
}
// NewStdlibAdapter returns a new StdlibAdapter wrapper around the passed
// logger. It's designed to be passed to log.SetOutput.
func NewStdlibAdapter(logger Logger, options ...StdlibAdapterOption) io.Writer {
a := StdlibAdapter{
Logger: logger,
timestampKey: "ts",
fileKey: "file",
messageKey: "msg",
}
for _, option := range options {
option(&a)
}
return a
}
func (a StdlibAdapter) Write(p []byte) (int, error) {
result := subexps(p)
keyvals := []interface{}{}
var timestamp string
if date, ok := result["date"]; ok && date != "" {
timestamp = date
}
if time, ok := result["time"]; ok && time != "" {
if timestamp != "" {
timestamp += " "
}
timestamp += time
}
if timestamp != "" {
keyvals = append(keyvals, a.timestampKey, timestamp)
}
if file, ok := result["file"]; ok && file != "" {
keyvals = append(keyvals, a.fileKey, file)
}
if msg, ok := result["msg"]; ok {
keyvals = append(keyvals, a.messageKey, msg)
}
if err := a.Logger.Log(keyvals...); err != nil {
return 0, err
}
return len(p), nil
}
const (
logRegexpDate = `(?P<date>[0-9]{4}/[0-9]{2}/[0-9]{2})?[ ]?`
logRegexpTime = `(?P<time>[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?)?[ ]?`
logRegexpFile = `(?P<file>.+?:[0-9]+)?`
logRegexpMsg = `(: )?(?P<msg>.*)`
)
var (
logRegexp = regexp.MustCompile(logRegexpDate + logRegexpTime + logRegexpFile + logRegexpMsg)
)
func subexps(line []byte) map[string]string {
m := logRegexp.FindSubmatch(line)
if len(m) < len(logRegexp.SubexpNames()) {
return map[string]string{}
}
result := map[string]string{}
for i, name := range logRegexp.SubexpNames() {
result[name] = string(m[i])
}
return result
}