Add the ability to wrap a log.Logger. Closes #45

Author: evanphx

intlogger.go

@@ -113,7 +113,9 @@ func newLogger(opts *LoggerOptions) *intLogger {
 
 	l.setColorization(opts)
 
-	if opts.TimeFormat != "" {
+	if opts.DisableTime {
+		l.timeFormat = ""
+	} else if opts.TimeFormat != "" {
 		l.timeFormat = opts.TimeFormat
 	}
 
@@ -180,8 +182,10 @@ var logImplFile = regexp.MustCompile(`github.com/hashicorp/go-hclog/.+logger.go$
 
 // Non-JSON logging format function
 func (l *intLogger) logPlain(t time.Time, name string, level Level, msg string, args ...interface{}) {
-	l.writer.WriteString(t.Format(l.timeFormat))
-	l.writer.WriteByte(' ')
+	if len(l.timeFormat) > 0 {
+		l.writer.WriteString(t.Format(l.timeFormat))
+		l.writer.WriteByte(' ')
+	}
 
 	s, ok := _levelToBracket[level]
 	if ok {

logger.go

@@ -230,6 +230,10 @@ type LoggerOptions struct {
 	// The time format to use instead of the default
 	TimeFormat string
 
+	// Control whether or not to display the time at all. This is required
+	// because setting TimeFormat to empty assumes the default format.
+	DisableTime bool
+
 	// Color the output. On Windows, colored logs are only avaiable for io.Writers that
 	// are concretely instances of *os.File.
 	Color ColorOption

stdlog.go

@@ -2,6 +2,7 @@ package hclog
 
 import (
 	"bytes"
+	"log"
 	"strings"
 )
 
@@ -72,3 +73,23 @@ func (s *stdlogAdapter) pickLevel(str string) (Level, string) {
 		return Info, str
 	}
 }
+
+type logWriter struct {
+	l *log.Logger
+}
+
+func (l *logWriter) Write(b []byte) (int, error) {
+	l.l.Println(string(bytes.TrimRight(b, " \n\t")))
+	return len(b), nil
+}
+
+// Takes a standard library logger and returns a Logger that will write to it
+func FromStandardLogger(l *log.Logger, opts *LoggerOptions) Logger {
+	var dl LoggerOptions = *opts
+
+	// Use the time format that log.Logger uses
+	dl.DisableTime = true
+	dl.Output = &logWriter{l}
+
+	return New(&dl)
+}

stdlog_test.go

@@ -2,6 +2,8 @@ package hclog
 
 import (
 	"bytes"
+	"log"
+	"regexp"
 	"strings"
 	"testing"
 
@@ -152,3 +154,19 @@ func TestStdlogAdapter_ForceLevel(t *testing.T) {
 		})
 	}
 }
+
+func TestFromLogger(t *testing.T) {
+	var buf bytes.Buffer
+
+	sl := log.New(&buf, "test-stdlib-log ", log.Ltime)
+
+	hl := FromStandardLogger(sl, &LoggerOptions{
+		Name: "hclog-inner",
+	})
+
+	hl.Info("this is a test", "name", "tester", "count", 1)
+
+	re := regexp.MustCompile(`test-stdlib-log [\d:]+ \[INFO\]  hclog-inner: this is a test: name=tester count=1`)
+
+	assert.True(t, re.Match(buf.Bytes()))
+}