logger with helper methods (#1216)

* support unix daemon socket

* refactor(logger): logger fields changed to map[string]interface{}

* improvement(logger): adding string to Level Parser

* improvement(logger): rename ParseLevel to GetLevel

* refactor(logger): adding basic logger

adding micro default logger, and refactor logger interface

* refactor(logger): moved basic logger to top level package

* refactor(logger): adding default logger

logger/default.go

@@ -0,0 +1,96 @@
+package logger
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"os"
+)
+
+type defaultLogger struct {
+	opts Options
+	err  error
+}
+
+// Init(opts...) should only overwrite provided options
+func (l *defaultLogger) Init(opts ...Option) error {
+	for _, o := range opts {
+		o(&l.opts)
+	}
+	return nil
+}
+
+func (l *defaultLogger) String() string {
+	return "default"
+}
+
+func (l *defaultLogger) Fields(fields map[string]interface{}) Logger {
+	l.opts.Fields = fields
+	return l
+}
+
+func (l *defaultLogger) Error(err error) Logger {
+	l.err = err
+	return l
+}
+
+func (l *defaultLogger) Log(level Level, v ...interface{}) {
+	if !l.opts.Level.Enabled(level) {
+		return
+	}
+	msg := fmt.Sprint(v...)
+
+	fields := l.opts.Fields
+	fields["level"] = level.String()
+	fields["message"] = msg
+	if l.err != nil {
+		fields["error"] = l.err.Error()
+	}
+
+	enc := json.NewEncoder(l.opts.Out)
+
+	if err := enc.Encode(fields); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func (l *defaultLogger) Logf(level Level, format string, v ...interface{}) {
+	if level < l.opts.Level {
+		return
+	}
+	msg := fmt.Sprintf(format, v...)
+
+	fields := l.opts.Fields
+	fields["level"] = level.String()
+	fields["message"] = msg
+	if l.err != nil {
+		fields["error"] = l.err.Error()
+	}
+
+	enc := json.NewEncoder(l.opts.Out)
+
+	if err := enc.Encode(fields); err != nil {
+		log.Fatal(err)
+	}
+
+}
+
+func (n *defaultLogger) Options() Options {
+	return n.opts
+}
+
+// NewLogger builds a new logger based on options
+func NewLogger(opts ...Option) Logger {
+	// Default options
+	options := Options{
+		Level:   InfoLevel,
+		Fields:  make(map[string]interface{}),
+		Out:     os.Stderr,
+		Context: context.Background(),
+	}
+
+	l := &defaultLogger{opts: options}
+	_ = l.Init(opts...)
+	return l
+}

logger/level.go

@@ -1,14 +1,24 @@
 package logger
 
+import "fmt"
+
 type Level int8
 
 const (
-	TraceLevel Level = iota - 1
+	// TraceLevel level. Designates finer-grained informational events than the Debug.
+	TraceLevel Level = iota - 2
+	// DebugLevel level. Usually only enabled when debugging. Very verbose logging.
 	DebugLevel
+	// InfoLevel is the default logging priority.
+	// General operational entries about what's going on inside the application.
 	InfoLevel
+	// WarnLevel level. Non-critical entries that deserve eyes.
 	WarnLevel
+	// ErrorLevel level. Logs. Used for errors that should definitely be noted.
 	ErrorLevel
+	// PanicLevel level, logs the message and then panics.
 	PanicLevel
+	// FatalLevel level. Logs and then calls `logger.Exit(1)`. highest level of severity.
 	FatalLevel
 )
 
@@ -24,10 +34,37 @@ func (l Level) String() string {
 		return "warn"
 	case ErrorLevel:
 		return "error"
-	case FatalLevel:
-		return "fatal"
 	case PanicLevel:
 		return "panic"
+	case FatalLevel:
+		return "fatal"
 	}
 	return ""
 }
+
+// Enabled returns true if the given level is at or above this level.
+func (l Level) Enabled(lvl Level) bool {
+	return lvl >= l
+}
+
+// GetLevel converts a level string into a logger Level value.
+// returns an error if the input string does not match known values.
+func GetLevel(levelStr string) (Level, error) {
+	switch levelStr {
+	case TraceLevel.String():
+		return TraceLevel, nil
+	case DebugLevel.String():
+		return DebugLevel, nil
+	case InfoLevel.String():
+		return InfoLevel, nil
+	case WarnLevel.String():
+		return WarnLevel, nil
+	case ErrorLevel.String():
+		return ErrorLevel, nil
+	case PanicLevel.String():
+		return PanicLevel, nil
+	case FatalLevel.String():
+		return FatalLevel, nil
+	}
+	return InfoLevel, fmt.Errorf("Unknown Level String: '%s', defaulting to NoLevel", levelStr)
+}

logger/logger.go

@@ -1,9 +1,9 @@
 // Package log provides a log interface
 package logger
 
-import (
+var (
-	"fmt"
+	// Default logger
-	"sync"
+	DefaultLogger Logger = NewLogger()
 )
 
 // Logger is a generic logging interface
@@ -24,45 +24,32 @@ type Logger interface {
 	String() string
 }
 
-var (
+func Init(opts ...Option) error {
-	mtx       sync.Mutex
+	return DefaultLogger.Init(opts...)
-	loggerMap = map[string]Logger{}
-)
-
-func Register(logger Logger) {
-	mtx.Lock()
-	defer mtx.Unlock()
-
-	loggerMap[logger.String()] = logger
 }
 
-func GetLogger(name string) (Logger, error) {
+func Error(err error) Logger {
-	l := loggerMap[name]
+	return DefaultLogger.Error(err)
-	if l == nil {
+}
-		return nil, fmt.Errorf("no such name logger found %s", name)
+
+func Fields(fields map[string]interface{}) Logger {
+	return DefaultLogger.Fields(fields)
+}
+
+func Log(level Level, v ...interface{}) {
+	DefaultLogger.Log(level, v...)
+}
+
+func Logf(level Level, format string, v ...interface{}) {
+	DefaultLogger.Logf(level, format, v...)
+}
+
+func SetGlobalLevel(lvl Level) {
+	if err := Init(WithLevel(lvl)); err != nil {
+		print(err)
 	}
-
-	return l, nil
 }
 
-// GetLevel converts a level string into a logger Level value.
+func String() string {
-// returns an error if the input string does not match known values.
+	return DefaultLogger.String()
-func GetLevel(levelStr string) (Level, error) {
-	switch levelStr {
-	case TraceLevel.String():
-		return TraceLevel, nil
-	case DebugLevel.String():
-		return DebugLevel, nil
-	case InfoLevel.String():
-		return InfoLevel, nil
-	case WarnLevel.String():
-		return WarnLevel, nil
-	case ErrorLevel.String():
-		return ErrorLevel, nil
-	case FatalLevel.String():
-		return FatalLevel, nil
-	case PanicLevel.String():
-		return PanicLevel, nil
-	}
-	return InfoLevel, fmt.Errorf("Unknown Level String: '%s', defaulting to NoLevel", levelStr)
 }

logger/options.go

@@ -2,30 +2,48 @@ package logger
 
 import (
 	"context"
+	"io"
 )
 
-// Option for load profiles maybe
-// eg. yml
-// micro:
-//   logger:
-//     name:
-//     dialect: zap/default/logrus
-//     zap:
-//       xxx:
-//     logrus:
-//       xxx:
 type Option func(*Options)
 
 type Options struct {
-	// The Log Level
+	// The logging level the logger should log at. default is `InfoLevel`
 	Level Level
-	// Other opts
+	// fields to always be logged
+	Fields map[string]interface{}
+	// It's common to set this to a file, or leave it default which is `os.Stderr`
+	Out io.Writer
+	// Alternative options
 	Context context.Context
 }
 
-// WithLevel sets the log level
+// WithFields set default fields for the logger
-func WithLevel(l Level) Option {
+func WithFields(fields map[string]interface{}) Option {
-	return func(o *Options) {
+	return func(args *Options) {
-		o.Level = l
+		args.Fields = fields
+	}
+}
+
+// WithLevel set default level for the logger
+func WithLevel(level Level) Option {
+	return func(args *Options) {
+		args.Level = level
+	}
+}
+
+// WithOutput set default output writer for the logger
+func WithOutput(out io.Writer) Option {
+	return func(args *Options) {
+		args.Out = out
+	}
+}
+
+func SetOption(k, v interface{}) Option {
+	return func(o *Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
 	}
 }