flagger/pkg/logging/logger.go

package logging

import (
	"fmt"
	"os"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

// NewLogger returns a zap sugared logger configured with json format and caller id
func NewLogger(logLevel string) (*zap.SugaredLogger, error) {
	level := zap.NewAtomicLevelAt(zapcore.InfoLevel)
	switch logLevel {
	case "debug":
		level = zap.NewAtomicLevelAt(zapcore.DebugLevel)
	case "info":
		level = zap.NewAtomicLevelAt(zapcore.InfoLevel)
	case "warn":
		level = zap.NewAtomicLevelAt(zapcore.WarnLevel)
	case "error":
		level = zap.NewAtomicLevelAt(zapcore.ErrorLevel)
	case "fatal":
		level = zap.NewAtomicLevelAt(zapcore.FatalLevel)
	case "panic":
		level = zap.NewAtomicLevelAt(zapcore.PanicLevel)
	}

	zapEncoderConfig := zapcore.EncoderConfig{
		TimeKey:        "ts",
		LevelKey:       "level",
		NameKey:        "logger",
		CallerKey:      "caller",
		MessageKey:     "msg",
		StacktraceKey:  "stacktrace",
		LineEnding:     zapcore.DefaultLineEnding,
		EncodeLevel:    zapcore.LowercaseLevelEncoder,
		EncodeTime:     zapcore.ISO8601TimeEncoder,
		EncodeDuration: zapcore.SecondsDurationEncoder,
		EncodeCaller:   zapcore.ShortCallerEncoder,
	}

	zapConfig := zap.Config{
		Level:       level,
		Development: false,
		Sampling: &zap.SamplingConfig{
			Initial:    100,
			Thereafter: 100,
		},
		Encoding:         "json",
		EncoderConfig:    zapEncoderConfig,
		OutputPaths:      []string{"stderr"},
		ErrorOutputPaths: []string{"stderr"},
	}

	logger, err := zapConfig.Build()
	if err != nil {
		return nil, err
	}
	return logger.Sugar(), nil
}

// Console writes to stdout if the console env var exists
func Console(a ...interface{}) (n int, err error) {
	if os.Getenv("console") != "" {
		return fmt.Fprintln(os.Stdout, a...)
	}

	return 0, nil
}