Structured logging (#8673)

* Implementing structured logging

* Changes to en.json to allow refactor to run.

* Fixing global logger

* Structured logger initalization.

* Add caller.

* Do some log redirection.

* Auto refactor

* Cleaning up l4g reference and removing dependancy.

* Removing junk.

* Copyright headers.

* Fixing tests

* Revert "Changes to en.json to allow refactor to run."

This reverts commit fd8249e99bcad0231e6ea65cd77c32aae9a54026.

* Fixing some auto refactor strangeness and typo.

* Making keys more human readable.

2 files changed, 185 insertions, 0 deletions

diff --git a/mlog/global.go b/mlog/global.go
new file mode 100644
index 000000000..91d5858a4
--- /dev/null
+++ b/mlog/global.go
@@ -0,0 +1,42 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package mlog
+
+import (
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+var globalLogger *Logger
+
+func InitGlobalLogger(logger *Logger) {
+	globalLogger = logger
+	Debug = globalLogger.Debug
+	Info = globalLogger.Info
+	Warn = globalLogger.Warn
+	Error = globalLogger.Error
+	Critical = globalLogger.Critical
+}
+
+func RedirectStdLog(logger *Logger) {
+	zap.RedirectStdLogAt(logger.zap.With(zap.String("source", "stdlog")), zapcore.ErrorLevel)
+}
+
+type LogFunc func(string, ...Field)
+
+// DON'T USE THIS Modify the level on the app logger
+func GloballyDisableDebugLogForTest() {
+	globalLogger.consoleLevel.SetLevel(zapcore.ErrorLevel)
+}
+
+// DON'T USE THIS Modify the level on the app logger
+func GloballyEnableDebugLogForTest() {
+	globalLogger.consoleLevel.SetLevel(zapcore.DebugLevel)
+}
+
+var Debug LogFunc
+var Info LogFunc
+var Warn LogFunc
+var Error LogFunc
+var Critical LogFunc
diff --git a/mlog/log.go b/mlog/log.go
new file mode 100644
index 000000000..801030c6c
--- /dev/null
+++ b/mlog/log.go
@@ -0,0 +1,143 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package mlog
+
+import (
+	"log"
+	"os"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	"gopkg.in/natefinch/lumberjack.v2"
+)
+
+const (
+	// Very verbose messages for debugging specific issues
+	LevelDebug = "debug"
+	// Default log level, informational
+	LevelInfo = "info"
+	// Warnings are messages about possible issues
+	LevelWarn = "warn"
+	// Errors are messages about things we know are problems
+	LevelError = "error"
+)
+
+// Type and function aliases from zap to limit the libraries scope into MM code
+type Field = zapcore.Field
+
+var Int64 = zap.Int64
+var Int = zap.Int
+var String = zap.String
+
+type LoggerConfiguration struct {
+	EnableConsole bool
+	ConsoleJson   bool
+	ConsoleLevel  string
+	EnableFile    bool
+	FileJson      bool
+	FileLevel     string
+	FileLocation  string
+}
+
+type Logger struct {
+	zap          *zap.Logger
+	consoleLevel zap.AtomicLevel
+	fileLevel    zap.AtomicLevel
+}
+
+func getZapLevel(level string) zapcore.Level {
+	switch level {
+	case LevelInfo:
+		return zapcore.InfoLevel
+	case LevelWarn:
+		return zapcore.WarnLevel
+	case LevelDebug:
+		return zapcore.DebugLevel
+	case LevelError:
+		return zapcore.ErrorLevel
+	default:
+		return zapcore.InfoLevel
+	}
+}
+
+func NewLogger(config *LoggerConfiguration) *Logger {
+	cores := []zapcore.Core{}
+	logger := &Logger{
+		consoleLevel: zap.NewAtomicLevelAt(getZapLevel(config.ConsoleLevel)),
+		fileLevel:    zap.NewAtomicLevelAt(getZapLevel(config.FileLevel)),
+	}
+
+	encoderConfig := zap.NewProductionEncoderConfig()
+	var encoder zapcore.Encoder
+	if config.ConsoleJson {
+		encoder = zapcore.NewJSONEncoder(encoderConfig)
+	} else {
+		encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+		encoder = zapcore.NewConsoleEncoder(encoderConfig)
+	}
+
+	if config.EnableConsole {
+		writer := zapcore.Lock(os.Stdout)
+		core := zapcore.NewCore(encoder, writer, logger.consoleLevel)
+		cores = append(cores, core)
+	}
+
+	if config.EnableFile {
+		writer := zapcore.AddSync(&lumberjack.Logger{
+			Filename: config.FileLocation,
+			MaxSize:  100,
+			Compress: true,
+		})
+		core := zapcore.NewCore(encoder, writer, logger.fileLevel)
+		cores = append(cores, core)
+	}
+
+	combinedCore := zapcore.NewTee(cores...)
+
+	logger.zap = zap.New(combinedCore,
+		zap.AddCallerSkip(2),
+		zap.AddCaller(),
+	)
+
+	return logger
+}
+
+func (l *Logger) ChangeLevels(config *LoggerConfiguration) {
+	l.consoleLevel.SetLevel(getZapLevel(config.ConsoleLevel))
+	l.fileLevel.SetLevel(getZapLevel(config.FileLevel))
+}
+
+func (l *Logger) SetConsoleLevel(level string) {
+	l.consoleLevel.SetLevel(getZapLevel(level))
+}
+
+func (l *Logger) With(fields ...Field) *Logger {
+	newlogger := *l
+	newlogger.zap = newlogger.zap.With(fields...)
+	return &newlogger
+}
+
+func (l *Logger) StdLog(fields ...Field) *log.Logger {
+	return zap.NewStdLog(l.With(fields...).zap)
+}
+
+func (l *Logger) Debug(message string, fields ...Field) {
+	l.zap.Debug(message, fields...)
+}
+
+func (l *Logger) Info(message string, fields ...Field) {
+	l.zap.Info(message, fields...)
+}
+
+func (l *Logger) Warn(message string, fields ...Field) {
+	l.zap.Warn(message, fields...)
+}
+
+func (l *Logger) Error(message string, fields ...Field) {
+	l.zap.Error(message, fields...)
+}
+
+func (l *Logger) Critical(message string, fields ...Field) {
+	l.zap.Error(message, fields...)
+}