Pass redirect field in login page to get a proper redirect

controllers/nginx/pkg/template/template.go

@@ -22,6 +22,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net"
+	"net/url"
 	"os"
 	"os/exec"
 	"strconv"
@@ -153,6 +154,7 @@ var (
 		"buildForwardedFor":           buildForwardedFor,
 		"trustHTTPHeaders":            trustHTTPHeaders,
 		"trustProxyProtocol":          trustProxyProtocol,
+		"buildAuthSignURL":            buildAuthSignURL,
 	}
 )
 
@@ -690,3 +692,23 @@ func trustProxyProtocol(input interface{}) bool {
 	return conf.Cfg.RealClientFrom == "tcp-proxy" ||
 		(conf.Cfg.RealClientFrom == "auto" && conf.Cfg.UseProxyProtocol)
 }
+
+func buildAuthSignURL(input interface{}) string {
+	s, ok := input.(string)
+	if !ok {
+		glog.Errorf("expected an 'string' type but %T was returned", input)
+		return ""
+	}
+
+	u, _ := url.Parse(s)
+	q := u.Query()
+	if len(q) == 0 {
+		return fmt.Sprintf("%v?rd=$request_uri", s)
+	}
+
+	if q.Get("rd") != "" {
+		return s
+	}
+
+	return fmt.Sprintf("%v&rd=$request_uri", s)
+}