Add support to reading password from stdin

auth.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"errors"
+	"io/ioutil"
 	"net/url"
+	"os"
 	"strings"
 
 	"github.com/reconquest/karma-go"
@@ -47,6 +49,17 @@ func GetCredentials(
 		}
 	}
 
+	if password == "-" {
+		b, err := ioutil.ReadAll(os.Stdin)
+		if err != nil {
+			return nil, karma.Format(
+				err,
+				"unable to read password from stdin",
+			)
+		}
+		password = string(b)
+	}
+
 	url, err := url.Parse(targetURL)
 	if err != nil {
 		return nil, karma.Format(