Add stdlog interpreter. (#8691)

mlog/stdlog.go

@@ -0,0 +1,74 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package mlog
+
+import (
+	"strings"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// Implementation of zapcore.Core to interpret log messages from a standard logger
+// and translate the levels to zapcore levels.
+type stdLogLevelInterpreterCore struct {
+	wrappedCore zapcore.Core
+}
+
+func stdLogInterpretZapEntry(entry zapcore.Entry) zapcore.Entry {
+	message := entry.Message
+	if strings.Index(message, "[DEBUG]") == 0 {
+		entry.Level = zapcore.DebugLevel
+		entry.Message = message[7:]
+	} else if strings.Index(message, "[DEBG]") == 0 {
+		entry.Level = zapcore.DebugLevel
+		entry.Message = message[6:]
+	} else if strings.Index(message, "[WARN]") == 0 {
+		entry.Level = zapcore.WarnLevel
+		entry.Message = message[6:]
+	} else if strings.Index(message, "[ERROR]") == 0 {
+		entry.Level = zapcore.ErrorLevel
+		entry.Message = message[7:]
+	} else if strings.Index(message, "[EROR]") == 0 {
+		entry.Level = zapcore.ErrorLevel
+		entry.Message = message[6:]
+	} else if strings.Index(message, "[ERR]") == 0 {
+		entry.Level = zapcore.ErrorLevel
+		entry.Message = message[5:]
+	} else if strings.Index(message, "[INFO]") == 0 {
+		entry.Level = zapcore.InfoLevel
+		entry.Message = message[6:]
+	}
+	return entry
+}
+
+func (s *stdLogLevelInterpreterCore) Enabled(lvl zapcore.Level) bool {
+	return s.wrappedCore.Enabled(lvl)
+}
+
+func (s *stdLogLevelInterpreterCore) With(fields []zapcore.Field) zapcore.Core {
+	return s.wrappedCore.With(fields)
+}
+
+func (s *stdLogLevelInterpreterCore) Check(entry zapcore.Entry, checkedEntry *zapcore.CheckedEntry) *zapcore.CheckedEntry {
+	entry = stdLogInterpretZapEntry(entry)
+	return s.wrappedCore.Check(entry, checkedEntry)
+}
+
+func (s *stdLogLevelInterpreterCore) Write(entry zapcore.Entry, fields []zapcore.Field) error {
+	entry = stdLogInterpretZapEntry(entry)
+	return s.wrappedCore.Write(entry, fields)
+}
+
+func (s *stdLogLevelInterpreterCore) Sync() error {
+	return s.wrappedCore.Sync()
+}
+
+func getStdLogOption() zap.Option {
+	return zap.WrapCore(
+		func(core zapcore.Core) zapcore.Core {
+			return &stdLogLevelInterpreterCore{core}
+		},
+	)
+}