[nspcc-dev#1770] node: Support runtime re-configuration of the logger

There is a need to re-configure storage node's logging on the
fly.

Provide `SubscribeConfigChanges` function to listen to changes of the
storage node config. Create dynamically configured `logger.Logger` in
`neofs-node` app and use it to log notifications about new Sidechain
blocks. Update `logger.Level` parameter on each `syscall.SIGHUP` signal.

Signed-off-by: Leonard Lyubich <ctulhurider@gmail.com>

cmd/neofs-node/config.go

@@ -81,7 +81,9 @@ type cfg struct {
 
 	internalErr chan error // channel for internal application errors at runtime
 
-	log *zap.Logger
+	log *logger.Logger
+
+	logN *logger.Logger
 
 	wg *sync.WaitGroup
 

cmd/neofs-node/config/config.go

@@ -2,7 +2,10 @@ package config
 
 import (
 	"fmt"
+	"os"
+	"os/signal"
 	"strings"
+	"syscall"
 
 	"github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/internal"
 	"github.com/spf13/viper"
@@ -52,7 +55,32 @@ func New(_ Prm, opts ...Option) *Config {
 		}
 	}
 
-	return &Config{
+	c := &Config{
 		v: v,
 	}
+
+	if len(o.reloadSubs) > 0 {
+		ch := make(chan os.Signal)
+		signal.Notify(ch, syscall.SIGHUP)
+
+		go func() {
+			for {
+				select {
+				case <-ch:
+					if o.path != "" {
+						err := v.ReadInConfig()
+						if err != nil {
+							panic(fmt.Errorf("failed to read config: %w", err))
+						}
+					}
+
+					for i := range o.reloadSubs {
+						o.reloadSubs[i](c)
+					}
+				}
+			}
+		}()
+	}
+
+	return c
 }

cmd/neofs-node/config/opts.go

@@ -2,6 +2,8 @@ package config
 
 type opts struct {
 	path string
+
+	reloadSubs []func(*Config)
 }
 
 func defaultOpts() *opts {
@@ -18,3 +20,11 @@ func WithConfigFile(path string) Option {
 		o.path = path
 	}
 }
+
+// SubscribeConfigChanges adds Config callback which will be invoked on each
+// syscall.SIGHUP signal.
+func SubscribeConfigChanges(f func(*Config)) Option {
+	return func(o *opts) {
+		o.reloadSubs = append(o.reloadSubs, f)
+	}
+}

cmd/neofs-node/main.go

@@ -10,9 +10,12 @@ import (
 	"syscall"
 
 	"github.com/nspcc-dev/neofs-node/cmd/neofs-node/config"
+	loggerconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/logger"
 	"github.com/nspcc-dev/neofs-node/misc"
 	"github.com/nspcc-dev/neofs-node/pkg/services/control"
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
 	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
 )
 
 const (
@@ -46,16 +49,52 @@ func main() {
 		os.Exit(SuccessReturnCode)
 	}
 
-	appCfg := config.New(config.Prm{}, config.WithConfigFile(*configFile))
+	var cfgLog logger.Config
 
-	err := validateConfig(appCfg)
+	logN, err := logger.NewConfigurable(&cfgLog)
+	fatalOnErr(err)
+
+	var appCfg *config.Config
+
+	appCfg = config.New(config.Prm{}, config.WithConfigFile(*configFile), config.SubscribeConfigChanges(func(c *config.Config) {
+		var lvl zapcore.Level
+
+		err = lvl.UnmarshalText([]byte(loggerconfig.Level(c)))
+		if err != nil {
+			logN.Write(logger.LevelError, "decode logging level",
+				logger.FieldError(err),
+			)
+			return
+		}
+
+		log.Println("decoded new level", lvl)
+
+		switch lvl {
+		default:
+			logN.Write(logger.LevelError, "unsupported logging level",
+				logger.FieldStringer("value", lvl),
+			)
+			return
+		case zapcore.DebugLevel:
+			cfgLog.SetLevel(logger.LevelDebug)
+		case zapcore.InfoLevel:
+			cfgLog.SetLevel(logger.LevelInfo)
+		case zapcore.WarnLevel:
+			cfgLog.SetLevel(logger.LevelWarn)
+		case zapcore.ErrorLevel:
+			cfgLog.SetLevel(logger.LevelError)
+		}
+	}))
+
+	err = validateConfig(appCfg)
 	fatalOnErr(err)
 
 	if *dryRunFlag {
 		return
 	}
 
 	c := initCfg(appCfg)
+	c.logN = logN
 
 	initApp(c)
 
@@ -79,7 +118,7 @@ func initAndLog(c *cfg, name string, initializer func(*cfg)) {
 }
 
 func initApp(c *cfg) {
-	c.ctx, c.ctxCancel = signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
+	c.ctx, c.ctxCancel = signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 
 	initAndLog(c, "storage engine", func(c *cfg) {
 		fatalOnErr(c.cfgObject.cfgLocalStorage.localStorage.Open())