MM-27744 disable Zap for unit tests. (#15398)

MM-27744 disable Zap for unit tests.

Zap has no concept of shutdown or close. Zap is only shutdown when the app exits. Not a problem for console logging, but when creating a new Zap logger that outputs to files on every unit test, that leaves no easy way to clean up until process exit. Depending on what else is running this can exhaust all file handles and cause unit tests to fail.

Zap is now disabled unit tests and uses Logr instead, regardless of config settings. `make test-server` peak file handle usage dropped from ~5K to less than 100.

mlog/global.go

@@ -5,6 +5,8 @@ package mlog
 
 import (
 	"context"
+	"log"
+	"sync/atomic"
 
 	"github.com/mattermost/logr"
 	"go.uber.org/zap"
@@ -32,11 +34,29 @@ func InitGlobalLogger(logger *Logger) {
 	ConfigAdvancedLogging = globalLogger.ConfigAdvancedLogging
 	ShutdownAdvancedLogging = globalLogger.ShutdownAdvancedLogging
 	AddTarget = globalLogger.AddTarget
+	RemoveTargets = globalLogger.RemoveTargets
 	EnableMetrics = globalLogger.EnableMetrics
 }
 
+// logWriterFunc provides access to mlog via io.Writer, so the standard logger
+// can be redirected to use mlog and whatever targets are defined.
+type logWriterFunc func([]byte) (int, error)
+
+func (lw logWriterFunc) Write(p []byte) (int, error) {
+	return lw(p)
+}
+
 func RedirectStdLog(logger *Logger) {
-	zap.RedirectStdLogAt(logger.zap.With(zap.String("source", "stdlog")).WithOptions(zap.AddCallerSkip(-2)), zapcore.ErrorLevel)
+	if atomic.LoadInt32(&disableZap) == 0 {
+		zap.RedirectStdLogAt(logger.zap.With(zap.String("source", "stdlog")).WithOptions(zap.AddCallerSkip(-2)), zapcore.ErrorLevel)
+		return
+	}
+
+	writer := func(p []byte) (int, error) {
+		Log(LvlStdLog, string(p))
+		return len(p), nil
+	}
+	log.SetOutput(logWriterFunc(writer))
 }
 
 type LogFunc func(string, ...Field)
@@ -45,7 +65,8 @@ 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
+type AddTargetFunc func(...logr.Target) error
+type RemoveTargetsFunc func(context.Context, func(TargetInfo) bool) error
 type EnableMetricsFunc func(logr.MetricsCollector) error
 
 // DON'T USE THIS Modify the level on the app logger
@@ -70,4 +91,5 @@ var Flush FlushFunc = defaultFlush
 var ConfigAdvancedLogging ConfigFunc = defaultAdvancedConfig
 var ShutdownAdvancedLogging ShutdownFunc = defaultAdvancedShutdown
 var AddTarget AddTargetFunc = defaultAddTarget
+var RemoveTargets RemoveTargetsFunc = defaultRemoveTargets
 var EnableMetrics EnableMetricsFunc = defaultEnableMetrics