feat(config): загрузка env-конфига (DSN, ENC-ключ, listen)

internal/config/config.go

@@ -0,0 +1,36 @@
+package config
+
+import (
+	"encoding/base64"
+	"fmt"
+	"os"
+)
+
+type Config struct {
+	DBDSN      string
+	EncKey     []byte
+	ListenAddr string
+}
+
+func Load() (*Config, error) {
+	dsn := os.Getenv("DNS_AR_DB_DSN")
+	if dsn == "" {
+		return nil, fmt.Errorf("config: DNS_AR_DB_DSN is required")
+	}
+	rawKey := os.Getenv("DNS_AR_ENC_KEY")
+	if rawKey == "" {
+		return nil, fmt.Errorf("config: DNS_AR_ENC_KEY is required")
+	}
+	key, err := base64.StdEncoding.DecodeString(rawKey)
+	if err != nil {
+		return nil, fmt.Errorf("config: DNS_AR_ENC_KEY must be base64: %w", err)
+	}
+	if len(key) != 32 {
+		return nil, fmt.Errorf("config: DNS_AR_ENC_KEY must decode to 32 bytes, got %d", len(key))
+	}
+	listen := os.Getenv("DNS_AR_LISTEN")
+	if listen == "" {
+		listen = ":8080"
+	}
+	return &Config{DBDSN: dsn, EncKey: key, ListenAddr: listen}, nil
+}