simplify logger creation (move logic into a function in main packages)

Ensure logger creation is consistent between Web and Collector
Create logger in main, pass down to downstream functions (like gin)
In debug mode, print a copy of AppConfig
Better debugging for logger.

webapp/backend/cmd/scrutiny/scrutiny.go

@@ -1,12 +1,15 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"github.com/analogj/scrutiny/webapp/backend/pkg/config"
 	"github.com/analogj/scrutiny/webapp/backend/pkg/errors"
 	"github.com/analogj/scrutiny/webapp/backend/pkg/version"
 	"github.com/analogj/scrutiny/webapp/backend/pkg/web"
-	log "github.com/sirupsen/logrus"
+	"github.com/sirupsen/logrus"
+	"io"
+	"log"
 	"os"
 	"time"
 
@@ -107,7 +110,18 @@ OPTIONS:
 						config.Set("log.file", c.String("log-file"))
 					}
 
-					webServer := web.AppEngine{Config: config}
+					webLogger, logFile, err := CreateLogger(config)
+					if logFile != nil {
+						defer logFile.Close()
+					}
+					if err != nil {
+						return err
+					}
+
+					settingsData, err := json.Marshal(config.AllSettings())
+					webLogger.Debug(string(settingsData), err)
+
+					webServer := web.AppEngine{Config: config, Logger: webLogger}
 
 					return webServer.Start()
 				},
@@ -140,3 +154,27 @@ OPTIONS:
 	}
 
 }
+
+func CreateLogger(appConfig config.Interface) (*logrus.Entry, *os.File, error) {
+	logger := logrus.WithFields(logrus.Fields{
+		"type": "web",
+	})
+	//set default log level
+	if level, err := logrus.ParseLevel(appConfig.GetString("log.level")); err == nil {
+		logger.Logger.SetLevel(level)
+	} else {
+		logger.Logger.SetLevel(logrus.InfoLevel)
+	}
+
+	var logFile *os.File
+	var err error
+	if appConfig.IsSet("log.file") && len(appConfig.GetString("log.file")) > 0 {
+		logFile, err = os.OpenFile(appConfig.GetString("log.file"), os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			logger.Logger.Errorf("Failed to open log file %s for output: %s", appConfig.GetString("log.file"), err)
+			return nil, logFile, err
+		}
+		logger.Logger.SetOutput(io.MultiWriter(os.Stderr, logFile))
+	}
+	return logger, logFile, nil
+}