frostfs-s3-lifecycler/cmd/s3-lifecycler/logger.go

package main

import (
	"fmt"
	"strings"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/metrics"
	"git.frostfs.info/TrueCloudLab/zapjournald"
	"github.com/nspcc-dev/neo-go/cli/options"
	"github.com/spf13/viper"
	"github.com/ssgreg/journald"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

const (
	destinationStdout   string = "stdout"
	destinationJournald string = "journald"
)

type Logger struct {
	logger *zap.Logger
	lvl    zap.AtomicLevel
}

func pickLogger(v *viper.Viper, appMetrics *metrics.AppMetrics) *Logger {
	switch dest := v.GetString(cfgLoggerDestination); dest {
	case destinationStdout:
		return newStdoutLogger(v, appMetrics)
	case destinationJournald:
		return newJournaldLogger(v, appMetrics)
	default:
		panic(fmt.Sprintf("wrong destination for logger: %s", dest))
	}
}

func newStdoutLogger(v *viper.Viper, appMetrics *metrics.AppMetrics) *Logger {
	c := newZapLogConfig(v)

	out, errSink, err := openZapSinks(c)
	if err != nil {
		panic(fmt.Sprintf("open zap sinks: %v", err.Error()))
	}

	core := zapcore.NewCore(zapcore.NewConsoleEncoder(c.EncoderConfig), out, c.Level)
	core = applyZapCoreMiddlewares(core, v, appMetrics)
	l := zap.New(core, zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)), zap.ErrorOutput(errSink))

	return &Logger{logger: l, lvl: c.Level}
}

func newJournaldLogger(v *viper.Viper, appMetrics *metrics.AppMetrics) *Logger {
	c := newZapLogConfig(v)

	// We can use NewJSONEncoder instead if, say, frontend
	// would like to access journald logs and parse them easily.
	encoder := zapjournald.NewPartialEncoder(zapcore.NewConsoleEncoder(c.EncoderConfig), zapjournald.SyslogFields)

	journalCore := zapjournald.NewCore(c.Level, encoder, &journald.Journal{}, zapjournald.SyslogFields)
	core := journalCore.With([]zapcore.Field{
		zapjournald.SyslogFacility(zapjournald.LogDaemon),
		zapjournald.SyslogIdentifier(),
		zapjournald.SyslogPid(),
	})
	core = applyZapCoreMiddlewares(core, v, appMetrics)
	l := zap.New(core, zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)))
	return &Logger{logger: l, lvl: c.Level}
}

func openZapSinks(cfg zap.Config) (zapcore.WriteSyncer, zapcore.WriteSyncer, error) {
	sink, closeOut, err := zap.Open(cfg.OutputPaths...)
	if err != nil {
		return nil, nil, err
	}
	errSink, _, err := zap.Open(cfg.ErrorOutputPaths...)
	if err != nil {
		closeOut()
		return nil, nil, err
	}
	return sink, errSink, nil
}

func applyZapCoreMiddlewares(core zapcore.Core, v *viper.Viper, appMetrics *metrics.AppMetrics) zapcore.Core {
	core = options.NewFilteringCore(core, filteringLogOption(v))

	if v.GetBool(cfgLoggerSamplingEnabled) {
		core = zapcore.NewSamplerWithOptions(core,
			v.GetDuration(cfgLoggerSamplingInterval),
			v.GetInt(cfgLoggerSamplingInitial),
			v.GetInt(cfgLoggerSamplingThereafter),
			zapcore.SamplerHook(func(_ zapcore.Entry, dec zapcore.SamplingDecision) {
				if dec&zapcore.LogDropped > 0 {
					appMetrics.DroppedLogsInc()
				}
			}))
	}

	return core
}

func newZapLogConfig(v *viper.Viper) zap.Config {
	lvl, err := getLogLevel(v.GetString(cfgLoggerLevel))
	if err != nil {
		panic(err)
	}

	c := zap.Config{
		Level:            zap.NewAtomicLevelAt(lvl),
		EncoderConfig:    zap.NewProductionEncoderConfig(),
		OutputPaths:      []string{"stderr"},
		ErrorOutputPaths: []string{"stderr"},
	}
	c.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder

	return c
}

func filteringLogOption(v *viper.Viper) options.FilterFunc {
	tags := v.GetStringSlice(cfgLoggerTags)

	return func(entry zapcore.Entry) bool {
		if !strings.HasPrefix(entry.Message, "tag:") {
			return true
		}

		msg := entry.Message[4:] // len("tag:")
		for _, tag := range tags {
			if strings.HasPrefix(msg, tag) {
				return true
			}
		}

		return false
	}
}

func getLogLevel(lvlStr string) (zapcore.Level, error) {
	var lvl zapcore.Level
	err := lvl.UnmarshalText([]byte(lvlStr))
	if err != nil {
		return lvl, fmt.Errorf("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,
		})
	}
	return lvl, nil
}