[#200] Reload config level and metrics on SIGHUP

Signed-off-by: Denis Kirillov <denis@nspcc.ru>

main.go

@@ -2,65 +2,16 @@ package main
 
 import (
 	"context"
-	"fmt"
 	"os/signal"
 	"syscall"
-
-	"github.com/spf13/viper"
-	"go.uber.org/zap"
-	"go.uber.org/zap/zapcore"
 )
 
 func main() {
-	var (
-		v = settings()
-		l = newLogger(v)
-	)
-	globalContext, _ := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
-	app := newApp(globalContext, WithLogger(l), WithConfig(v))
-	go app.Serve(globalContext)
-	app.Wait()
-}
-
-// newLogger constructs a zap.Logger instance for current application.
-// Panics on failure.
-//
-// Logger is built from zap's production logging configuration with:
-//   - parameterized level (debug by default)
-//   - console encoding
-//   - ISO8601 time encoding
-//
-// Logger records a stack trace for all messages at or above fatal level.
-//
-// See also zapcore.Level, zap.NewProductionConfig, zap.AddStacktrace.
-func newLogger(v *viper.Viper) *zap.Logger {
-	var lvl zapcore.Level
-	lvlStr := v.GetString(cfgLoggerLevel)
-	err := lvl.UnmarshalText([]byte(lvlStr))
-	if err != nil {
-		panic(fmt.Sprintf("incorrect logger level configuration %s (%v), "+
-			"value should be one of %v", lvlStr, err, [...]zapcore.Level{
-			zapcore.DebugLevel,
-			zapcore.InfoLevel,
-			zapcore.WarnLevel,
-			zapcore.ErrorLevel,
-			zapcore.DPanicLevel,
-			zapcore.PanicLevel,
-			zapcore.FatalLevel,
-		}))
-	}
-
-	c := zap.NewProductionConfig()
-	c.Level = zap.NewAtomicLevelAt(lvl)
-	c.Encoding = "console"
-	c.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
-
-	l, err := c.Build(
-		zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)),
-	)
-	if err != nil {
-		panic(fmt.Sprintf("build zap logger instance: %v", err))
-	}
-
-	return l
+	globalContext, _ := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	v := settings()
+	logger, atomicLevel := newLogger(v)
+
+	application := newApp(globalContext, WithLogger(logger, atomicLevel), WithConfig(v))
+	go application.Serve(globalContext)
+	application.Wait()
 }