Adjust settings functions

cfg/cfg.go

@@ -2,58 +2,44 @@ package cfg
 
 import (
 	"fmt"
-	"os"
 
 	"github.com/alecthomas/kong"
 )
 
 type AppSettings struct {
-	ServerAddress string
-	DataFile      string
-	DataURL       string
-}
-
-var cliStruct struct {
 	ServerAddress string `name:"listen-address" env:"GEOIP_LISTEN_ADDRESS" help:"Address to use for the metrics server" default:"${default_address}"`
 	DataFile      string `name:"data-file" env:"GEOIP_DATA_FILE" help:"path to data file" default:"${default_file_path}"`
-	DataURL       string `name:"data-url" env:"GEOIP_DATA_URL" help:"url to data file" default:"${default_file_url}"`
+	DataURL       string `name:"data-url" env:"GEOIP_DATA_URL" help:"url to data file"`
 }
 
-func Parse() *AppSettings {
+func NewAppSettings() *AppSettings {
+	return &AppSettings{}
+}
+
+func (s *AppSettings) Parse() error {
 	ctx := kong.Parse(
-		&cliStruct,
+		s,
 		kong.Vars{
 			"default_address":   ":8080",
 			"default_file_path": "./data.csv",
-			"default_file_url":  "https://data.example.com/test.csv",
 		},
 		kong.Name("country_geo_locations"),
 		kong.Description("🚀 Start a simple web server for GeoIP data"),
 		kong.UsageOnError(),
 	)
 
-	validateFlags(ctx)
-	settings := &AppSettings{
-		ServerAddress: cliStruct.ServerAddress,
-		DataFile:      cliStruct.DataFile,
-		DataURL:       cliStruct.DataURL,
+	err := validateFlags(*s)
+	if err != nil {
+		ctx.PrintUsage(false)
+		fmt.Println()
+		return err
 	}
-	return settings
+	return nil
 }
 
-func validateFlags(cliCtx *kong.Context) {
-	var flagsValid = true
-	var messages = []string{}
-	if cliStruct.ServerAddress == "" {
-		messages = append(messages, "error: invalid server address, must not be blank")
-		flagsValid = false
-	}
-	if !flagsValid {
-		cliCtx.PrintUsage(false)
-		fmt.Println()
-		for i := 0; i < len(messages); i++ {
-			fmt.Println(messages[i])
-		}
-		os.Exit(1)
+func validateFlags(settings AppSettings) error {
+	if settings.DataURL == "" {
+		return fmt.Errorf("error: invalid data url, must not be blank")
 	}
+	return nil
 }

main.go

@@ -18,7 +18,11 @@ import (
 )
 
 func main() {
-	appSettings := cfg.Parse()
+	appSettings := cfg.NewAppSettings()
+	if err := appSettings.Parse(); err != nil {
+		panic(err)
+	}
+
 	handleGracefulShutdown()
 	if !downloader.FileExists(appSettings.DataFile) {
 		downloader.DownloadFile(appSettings.DataFile, appSettings.DataURL)