Add stdlog interpreter. (#8691)

3 files changed, 117 insertions, 1 deletions

diff --git a/mlog/log.go b/mlog/log.go
index 801030c6c..22db0c7b1 100644
--- a/mlog/log.go
+++ b/mlog/log.go
@@ -119,7 +119,7 @@ func (l *Logger) With(fields ...Field) *Logger {
 }
 
 func (l *Logger) StdLog(fields ...Field) *log.Logger {
-	return zap.NewStdLog(l.With(fields...).zap)
+	return zap.NewStdLog(l.With(fields...).zap.WithOptions(getStdLogOption()))
 }
 
 func (l *Logger) Debug(message string, fields ...Field) {
diff --git a/mlog/stdlog.go b/mlog/stdlog.go
new file mode 100644
index 000000000..a875b2e32
--- /dev/null
+++ b/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}
+		},
+	)
+}
diff --git a/mlog/stdlog_test.go b/mlog/stdlog_test.go
new file mode 100644
index 000000000..e924b406b
--- /dev/null
+++ b/mlog/stdlog_test.go
@@ -0,0 +1,42 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package mlog
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.uber.org/zap/zapcore"
+)
+
+func TestStdLogInterpretZapEntry(t *testing.T) {
+	for _, tc := range []struct {
+		testname        string
+		message         string
+		expectedMessage string
+		expectedLevel   zapcore.Level
+	}{
+		{"Debug Basic", "[DEBUG]My message", "My message", zapcore.DebugLevel},
+		{"Debug Basic2", "[DEBG]My message", "My message", zapcore.DebugLevel},
+		{"Warn Basic", "[WARN]My message", "My message", zapcore.WarnLevel},
+		{"Error Basic", "[ERROR]My message", "My message", zapcore.ErrorLevel},
+		{"Error Basic2", "[EROR]My message", "My message", zapcore.ErrorLevel},
+		{"Error Basic3", "[ERR]My message", "My message", zapcore.ErrorLevel},
+		{"Info Basic", "[INFO]My message", "My message", zapcore.InfoLevel},
+		{"Unknown level", "[UNKNOWN]My message", "[UNKNOWN]My message", zapcore.PanicLevel},
+		{"No level", "My message", "My message", zapcore.PanicLevel},
+		{"Empty message", "", "", zapcore.PanicLevel},
+		{"Malformed level", "INFO]My message", "INFO]My message", zapcore.PanicLevel},
+	} {
+		t.Run(tc.testname, func(t *testing.T) {
+			inEntry := zapcore.Entry{
+				Level:   zapcore.PanicLevel,
+				Message: tc.message,
+			}
+			resultEntry := stdLogInterpretZapEntry(inEntry)
+			assert.Equal(t, tc.expectedMessage, resultEntry.Message)
+			assert.Equal(t, tc.expectedLevel, resultEntry.Level)
+		})
+	}
+}