Support time.Duration config parameters

config.go

@@ -10,6 +10,7 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/spf13/pflag"
 )
@@ -100,6 +101,29 @@ func execTags(in interface{}, fs *pflag.FlagSet) error {
 		value = envDefault(typeField.Tag.Get("env"), value)
 		parts := strings.Split(typeField.Tag.Get("flag"), ",")
 
+		switch typeField.Type {
+		case reflect.TypeOf(time.Duration(0)):
+			v, err := time.ParseDuration(value)
+			if err != nil {
+				if value == "" {
+					v = time.Duration(0)
+				} else {
+					return err
+				}
+			}
+
+			if typeField.Tag.Get("flag") != "" {
+				if len(parts) == 1 {
+					fs.DurationVar(valField.Addr().Interface().(*time.Duration), parts[0], v, typeField.Tag.Get("description"))
+				} else {
+					fs.DurationVarP(valField.Addr().Interface().(*time.Duration), parts[0], parts[1], v, typeField.Tag.Get("description"))
+				}
+			} else {
+				valField.Set(reflect.ValueOf(v))
+			}
+			continue
+		}
+
 		switch typeField.Type.Kind() {
 		case reflect.String:
 			if typeField.Tag.Get("flag") != "" {

duration_test.go

@@ -0,0 +1,41 @@
+package rconfig
+
+import (
+	"time"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Duration", func() {
+	type t struct {
+		Test    time.Duration `flag:"duration"`
+		TestS   time.Duration `flag:"other-duration,o"`
+		TestDef time.Duration `default:"30h"`
+	}
+
+	var (
+		err  error
+		args []string
+		cfg  t
+	)
+
+	BeforeEach(func() {
+		cfg = t{}
+		args = []string{
+			"--duration=23s", "-o", "45m",
+		}
+	})
+
+	JustBeforeEach(func() {
+		err = parse(&cfg, args)
+	})
+
+	It("should not have errored", func() { Expect(err).NotTo(HaveOccurred()) })
+	It("should have the expected values", func() {
+		Expect(cfg.Test).To(Equal(23 * time.Second))
+		Expect(cfg.TestS).To(Equal(45 * time.Minute))
+
+		Expect(cfg.TestDef).To(Equal(30 * time.Hour))
+	})
+})