config.go

package logger

import (
	"os"

	"github.com/pkg/errors"
	"github.com/samber/lo"
	"github.com/spf13/pflag"
)

// Format defines the format of log output.
type Format string

const (
	// FormatConsole causes logs to be printed in console format delivered by zap.
	FormatConsole Format = "console"

	// FormatJSON causes logs to be printed in JSON format delivered by zap.
	FormatJSON Format = "json"

	// FormatYAML causes logs to be printed in YAML.
	FormatYAML Format = "yaml"
)

// Config stores configuration of the logger.
type Config struct {
	// Format defines the format of log output.
	Format Format

	// Verbose turns on verbose logging.
	Verbose bool
}

// DefaultConfig stores handy default configuration.
var DefaultConfig = Config{
	Format:  FormatYAML,
	Verbose: false,
}

var validFormats = map[Format]bool{
	FormatConsole: true,
	FormatJSON:    true,
	FormatYAML:    true,
}

// ConfigureWithCLI configures logger based on CLI flags.
func ConfigureWithCLI(defaultConfig Config) Config {
	flags := pflag.NewFlagSet("logger", pflag.ContinueOnError)
	flags.ParseErrorsWhitelist.UnknownFlags = true
	AddFlags(defaultConfig, flags)
	// Dummy flag to turn off printing usage of this flag set
	flags.BoolP("help", "h", false, "")

	_ = flags.Parse(os.Args[1:])

	defaultConfig.Format = Format(lo.Must(flags.GetString("log-format")))
	defaultConfig.Verbose = lo.Must(flags.GetBool("verbose"))
	if !validFormats[defaultConfig.Format] {
		panic(errors.Errorf("incorrect logging format %s", defaultConfig.Format))
	}

	return defaultConfig
}

// Flags returns new flag set preconfigured with logger-specific options.
func Flags(defaultConfig Config, name string) *pflag.FlagSet {
	flags := pflag.NewFlagSet(name, pflag.ContinueOnError)
	AddFlags(defaultConfig, flags)
	return flags
}

// AddFlags adds flags defined by logger.
func AddFlags(defaultConfig Config, flags *pflag.FlagSet) {
	flags.String("log-format", string(defaultConfig.Format), "Format of log output: console | json")
	flags.BoolP("verbose", "v", defaultConfig.Verbose, "Turns on verbose logging")
}