MM-25731 Advanced Logging (#14888)

Adds Advanced Logging to server. Advanced Logging is an optional logging capability that allows customers to send log records to any number of destinations.

Supported destinations:
- file
- syslog (with out without TLS)
- raw TCP socket (with out without TLS)

Allows developers to specify discrete log levels as well as the standard trace, debug, info, ... panic. Existing code and logging API usage is unchanged.

Log records are emitted asynchronously to reduce latency to the caller. Supports hot-reloading of logger config, including adding removing targets.

Advanced Logging is configured within config.json via "LogSettings.AdvancedLoggingConfig" which can contain a filespec to another config file, a database DSN, or JSON.

mlog/global.go

@@ -4,6 +4,9 @@
 package mlog
 
 import (
+	"context"
+
+	"github.com/mattermost/logr"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )
@@ -11,6 +14,10 @@ import (
 var globalLogger *Logger
 
 func InitGlobalLogger(logger *Logger) {
+	// Clean up previous instance.
+	if globalLogger != nil && globalLogger.logrLogger != nil {
+		globalLogger.logrLogger.Logr().Shutdown()
+	}
 	glob := *logger
 	glob.zap = glob.zap.WithOptions(zap.AddCallerSkip(1))
 	globalLogger = &glob
@@ -19,6 +26,12 @@ func InitGlobalLogger(logger *Logger) {
 	Warn = globalLogger.Warn
 	Error = globalLogger.Error
 	Critical = globalLogger.Critical
+	Log = globalLogger.Log
+	LogM = globalLogger.LogM
+	Flush = globalLogger.Flush
+	ConfigAdvancedLogging = globalLogger.ConfigAdvancedLogging
+	ShutdownAdvancedLogging = globalLogger.ShutdownAdvancedLogging
+	AddTarget = globalLogger.AddTarget
 }
 
 func RedirectStdLog(logger *Logger) {
@@ -26,6 +39,12 @@ func RedirectStdLog(logger *Logger) {
 }
 
 type LogFunc func(string, ...Field)
+type LogFuncCustom func(LogLevel, string, ...Field)
+type LogFuncCustomMulti func([]LogLevel, string, ...Field)
+type FlushFunc func(context.Context) error
+type ConfigFunc func(cfg LogTargetCfg) error
+type ShutdownFunc func(context.Context) error
+type AddTargetFunc func(logr.Target) error
 
 // DON'T USE THIS Modify the level on the app logger
 func GloballyDisableDebugLogForTest() {
@@ -42,3 +61,10 @@ var Info LogFunc = defaultInfoLog
 var Warn LogFunc = defaultWarnLog
 var Error LogFunc = defaultErrorLog
 var Critical LogFunc = defaultCriticalLog
+var Log LogFuncCustom = defaultCustomLog
+var LogM LogFuncCustomMulti = defaultCustomMultiLog
+var Flush FlushFunc = defaultFlush
+
+var ConfigAdvancedLogging ConfigFunc = defaultAdvancedConfig
+var ShutdownAdvancedLogging ShutdownFunc = defaultAdvancedShutdown
+var AddTarget AddTargetFunc = defaultAddTarget