refactored for easier mainenance, add Alloc and Metrics classes

cmd/config.go

@@ -0,0 +1,98 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+
+	flag "github.com/spf13/pflag"
+
+	"github.com/knadh/koanf/providers/posflag"
+	koanf "github.com/knadh/koanf/v2"
+)
+
+const (
+	Version = `v0.0.1`
+	SLEEP   = 5
+	Usage   = `io-exporter [options] <file>
+Options:
+-t --timeout <int>          When should the operation timeout in seconds
+-l --label   <label=value>  Add label to exported metric
+-h --help                   Show help
+-v --version                Show program version`
+)
+
+// config via commandline flags
+type Config struct {
+	Showversion bool     `koanf:"version"` // -v
+	Showhelp    bool     `koanf:"help"`    // -h
+	Label       []string `koanf:"label"`   // -v
+	Timeout     int      `koanf:"timeout"` // -t
+	Port        int      `koanf:"port"`    // -p
+
+	File   string
+	Labels []Label
+}
+
+func InitConfig(output io.Writer) (*Config, error) {
+	var kloader = koanf.New(".")
+
+	// setup custom usage
+	flagset := flag.NewFlagSet("config", flag.ContinueOnError)
+	flagset.Usage = func() {
+		_, err := fmt.Fprintln(output, Usage)
+		if err != nil {
+			log.Fatalf("failed to print to output: %s", err)
+		}
+	}
+
+	// parse commandline flags
+	flagset.BoolP("version", "v", false, "show program version")
+	flagset.BoolP("help", "h", false, "show help")
+	flagset.StringArrayP("label", "l", nil, "additional labels")
+	flagset.IntP("timeout", "t", 1, "timeout for file operation in seconds")
+	flagset.IntP("port", "p", 9187, "prometheus metrics port to listen to")
+
+	if err := flagset.Parse(os.Args[1:]); err != nil {
+		return nil, fmt.Errorf("failed to parse program arguments: %w", err)
+	}
+
+	// command line setup
+	if err := kloader.Load(posflag.Provider(flagset, ".", kloader), nil); err != nil {
+		return nil, fmt.Errorf("error loading flags: %w", err)
+	}
+
+	// fetch values
+	conf := &Config{}
+	if err := kloader.Unmarshal("", &conf); err != nil {
+		return nil, fmt.Errorf("error unmarshalling: %w", err)
+	}
+
+	// arg is the file under test
+	if len(flagset.Args()) > 0 {
+		conf.File = flagset.Args()[0]
+	} else {
+		if !conf.Showversion {
+			flagset.Usage()
+			os.Exit(1)
+		}
+	}
+
+	for _, label := range conf.Label {
+		if len(label) == 0 {
+			continue
+		}
+
+		parts := strings.Split(label, "=")
+		if len(parts) != 2 {
+			return nil, errors.New("invalid label spec: " + label + ", expected label=value")
+		}
+
+		conf.Labels = append(conf.Labels, Label{Name: parts[0], Value: parts[1]})
+	}
+
+	return conf, nil
+}