huge refactoring

internal/pkg/xlog/doc.go

@@ -0,0 +1,17 @@
+/*
+Package xlog defines a standard logger
+for the application.
+
+It uses structured logging thanks to
+https://github.com/sirupsen/logrus.
+
+All messages have at least two fields:
+
+A "trace" field which helps to identify
+messages belonging to the same context.
+
+An "op" field which helps to identify
+the logical operation associated
+with the message.
+*/
+package xlog

internal/pkg/xlog/xlog.go

@@ -0,0 +1,141 @@
+package xlog
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/mattn/go-isatty"
+	"github.com/sirupsen/logrus"
+)
+
+// Level helps setting the severity
+// of the messages displayed.
+type Level string
+
+const (
+	// DebugLevel is the lowest level.
+	DebugLevel Level = "DEBUG"
+	// InfoLevel is the intermediate level.
+	InfoLevel Level = "INFO"
+	// ErrorLevel is the highest level.
+	ErrorLevel Level = "ERROR"
+)
+
+// Logger enforces specific log message formats.
+type Logger struct {
+	entry *logrus.Entry
+	level Level
+}
+
+// New returns a xlog.Logger.
+func New(level Level, trace string) Logger {
+	l := logrus.New()
+	l.SetLevel(mustLogrusLevel(level))
+	if !isatty.IsTerminal(os.Stdout.Fd()) {
+		l.SetFormatter(&logrus.JSONFormatter{})
+	}
+	return Logger{
+		entry: l.WithField("trace", trace),
+		level: level,
+	}
+}
+
+func mustLogrusLevel(level Level) logrus.Level {
+	const op string = "xlog.mustLogrusLevel"
+	switch level {
+	case DebugLevel:
+		return logrus.DebugLevel
+	case InfoLevel:
+		return logrus.InfoLevel
+	case ErrorLevel:
+		return logrus.ErrorLevel
+	default:
+		panic(fmt.Sprintf("%s: '%s' is not associated with any logrus.Level", op, level))
+	}
+}
+
+// Levels returns a slice of string
+// with all severities.
+func Levels() []string {
+	return []string{
+		string(DebugLevel),
+		string(InfoLevel),
+		string(ErrorLevel),
+	}
+}
+
+/*
+MustParseLevel returns the Level corresponding
+to given string.
+
+It panics if no correspondence.
+*/
+func MustParseLevel(level string) Level {
+	const op string = "xlog.MustParseLevel"
+	switch level {
+	case string(DebugLevel):
+		return DebugLevel
+	case string(InfoLevel):
+		return InfoLevel
+	case string(ErrorLevel):
+		return ErrorLevel
+	default:
+		panic(fmt.Sprintf("%s: '%s' is not one of '%v'", op, level, Levels()))
+	}
+}
+
+// Level returns the current Level.
+func (l Logger) Level() Level {
+	return l.level
+}
+
+// WithFields returns a new xlog.Logger with
+// given fields.
+func (l Logger) WithFields(fields map[string]interface{}) Logger {
+	return Logger{
+		entry: l.entry.WithFields(fields),
+		level: l.level,
+	}
+}
+
+// DebugOp logs a debug message for given
+// logical operation.
+func (l Logger) DebugOp(op, message string) {
+	l.entry.WithField("op", op).Debug(message)
+}
+
+// DebugfOp logs a debug message for given
+// logical operation and format.
+func (l Logger) DebugfOp(op, format string, args ...interface{}) {
+	l.entry.WithField("op", op).Debugf(format, args...)
+}
+
+// InfoOp logs an info message for given
+// logical operation.
+func (l Logger) InfoOp(op, message string) {
+	l.entry.WithField("op", op).Info(message)
+}
+
+// InfofOp logs an info message for given
+// logical operation and format.
+func (l Logger) InfofOp(op, format string, args ...interface{}) {
+	l.entry.WithField("op", op).Infof(format, args...)
+}
+
+// ErrorOp logs an error for given
+// logical operation.
+func (l Logger) ErrorOp(op string, err error) {
+	l.entry.WithField("op", op).Error(err.Error())
+}
+
+// ErrorfOp logs an error message for given
+// logical operation and format.
+func (l Logger) ErrorfOp(op, format string, args ...interface{}) {
+	l.entry.WithField("op", op).Errorf(format, args...)
+}
+
+// FatalOp logs an error for given
+// logical operation and exit 1.
+func (l Logger) FatalOp(op string, err error) {
+	l.entry.WithField("op", op).Fatal(err.Error())
+}