Logger interface and tmLogger impl based on go-kit

log/tm_logger.go

@@ -0,0 +1,74 @@
+package log
+
+import (
+	"fmt"
+	"io"
+
+	kitlog "github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
+	"github.com/go-kit/kit/log/term"
+)
+
+const (
+	msgKey = "_msg" // "_" prefixed to avoid collisions
+)
+
+type tmLogger struct {
+	srcLogger kitlog.Logger
+}
+
+// NewTmTermLogger returns a logger that encodes msg and keyvals to the Writer
+// using go-kit's log as an underlying logger and our custom formatter. Note
+// that underlying logger could be swapped with something else.
+func NewTmLogger(w io.Writer) Logger {
+	// Color by level value
+	colorFn := func(keyvals ...interface{}) term.FgBgColor {
+		if keyvals[0] != level.Key() {
+			panic(fmt.Sprintf("expected level key to be first, got %v", keyvals[0]))
+		}
+		switch keyvals[1].(level.Value).String() {
+		case "debug":
+			return term.FgBgColor{Fg: term.DarkGray}
+		case "error":
+			return term.FgBgColor{Fg: term.Red}
+		default:
+			return term.FgBgColor{}
+		}
+	}
+
+	srcLogger := term.NewLogger(w, NewTmfmtLogger, colorFn)
+	srcLogger = level.NewFilter(srcLogger, level.AllowInfo())
+	return &tmLogger{srcLogger}
+}
+
+// WithLevel returns a copy of the logger with a level set to lvl.
+func (l *tmLogger) WithLevel(lvl string) Logger {
+	switch lvl {
+	case "info":
+		return &tmLogger{level.NewFilter(l.srcLogger, level.AllowInfo())}
+	case "debug":
+		return &tmLogger{level.NewFilter(l.srcLogger, level.AllowDebug())}
+	case "error":
+		return &tmLogger{level.NewFilter(l.srcLogger, level.AllowError())}
+	default:
+		panic(fmt.Sprintf("Unexpected level %v, expect either \"info\" or \"debug\" or \"error\"", lvl))
+	}
+}
+
+// Info logs a message at level Info.
+func (l *tmLogger) Info(msg string, keyvals ...interface{}) error {
+	lWithLevel := level.Info(l.srcLogger)
+	return kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...)
+}
+
+// Debug logs a message at level Debug.
+func (l *tmLogger) Debug(msg string, keyvals ...interface{}) error {
+	lWithLevel := level.Debug(l.srcLogger)
+	return kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...)
+}
+
+// Error logs a message at level Error.
+func (l *tmLogger) Error(msg string, keyvals ...interface{}) error {
+	lWithLevel := level.Error(l.srcLogger)
+	return kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...)
+}