Refactor directory structure

pkg/log/log.go

@@ -0,0 +1,125 @@
+// Provides a simple way of logging with different levels.
+// Time/Data are not logged on purpose because systemd adds
+// them for us.
+//
+// Uses these prefixes: https://www.freedesktop.org/software/systemd/man/sd-daemon.html
+package log
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+)
+
+var (
+	DebugWriter io.Writer = os.Stderr
+	InfoWriter  io.Writer = os.Stderr
+	WarnWriter  io.Writer = os.Stderr
+	ErrWriter   io.Writer = os.Stderr
+)
+
+var (
+	DebugPrefix string = "<7>[DEBUG]   "
+	InfoPrefix  string = "<6>[INFO]    "
+	WarnPrefix  string = "<4>[WARNING] "
+	ErrPrefix   string = "<3>[ERROR]   "
+)
+
+var (
+	DebugLog *log.Logger = log.New(DebugWriter, DebugPrefix, 0)
+	InfoLog  *log.Logger = log.New(InfoWriter, InfoPrefix, 0)
+	WarnLog  *log.Logger = log.New(WarnWriter, WarnPrefix, 0)
+	ErrLog   *log.Logger = log.New(ErrWriter, ErrPrefix, 0)
+)
+
+func init() {
+	if lvl, ok := os.LookupEnv("LOGLEVEL"); ok {
+		switch lvl {
+		case "err", "fatal":
+			WarnWriter = io.Discard
+			fallthrough
+		case "warn":
+			InfoWriter = io.Discard
+			fallthrough
+		case "info":
+			DebugWriter = io.Discard
+		case "debug":
+			// Nothing to do...
+		default:
+			Warnf("environment variable LOGLEVEL has invalid value %#v", lvl)
+		}
+	}
+}
+
+func Debug(v ...interface{}) {
+	if DebugWriter != io.Discard {
+		DebugLog.Print(v...)
+	}
+}
+
+func Info(v ...interface{}) {
+	if InfoWriter != io.Discard {
+		InfoLog.Print(v...)
+	}
+}
+
+func Print(v ...interface{}) {
+	Info(v...)
+}
+
+func Warn(v ...interface{}) {
+	if WarnWriter != io.Discard {
+		WarnLog.Print(v...)
+	}
+}
+
+func Error(v ...interface{}) {
+	if ErrWriter != io.Discard {
+		ErrLog.Print(v...)
+	}
+}
+
+func Fatal(v ...interface{}) {
+	Error(v...)
+	os.Exit(1)
+}
+
+func Debugf(format string, v ...interface{}) {
+	if DebugWriter != io.Discard {
+		DebugLog.Printf(format, v...)
+	}
+}
+
+func Infof(format string, v ...interface{}) {
+	if InfoWriter != io.Discard {
+		InfoLog.Printf(format, v...)
+	}
+}
+
+func Printf(format string, v ...interface{}) {
+	Infof(format, v...)
+}
+
+func Finfof(w io.Writer, format string, v ...interface{}) {
+	if w != io.Discard {
+		fmt.Fprintf(InfoWriter, InfoPrefix+format+"\n", v...)
+	}
+}
+
+func Warnf(format string, v ...interface{}) {
+	if WarnWriter != io.Discard {
+		WarnLog.Printf(format, v...)
+	}
+}
+
+func Errorf(format string, v ...interface{}) {
+	if ErrWriter != io.Discard {
+		ErrLog.Printf(format, v...)
+	}
+}
+
+func Fatalf(format string, v ...interface{}) {
+	Errorf(format, v...)
+	os.Exit(1)
+}