CONSOLE-2535: Internationalize login page

go.mod

@@ -20,6 +20,7 @@ require (
 	github.com/spf13/pflag v1.0.5
 	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
 	golang.org/x/oauth2 v0.0.0-20191202225959-858c2ad4c8b6
+	golang.org/x/text v0.3.3
 	gopkg.in/ldap.v2 v2.5.1
 	k8s.io/api v0.19.2
 	k8s.io/apimachinery v0.19.2

pkg/server/login/locales.go

@@ -0,0 +1,53 @@
+package login
+
+import "golang.org/x/text/language"
+
+func getLocale(langBase string) map[string]string {
+	switch langBase {
+	case language.English.String():
+		return locale_en
+	case language.Chinese.String():
+		return locale_zh
+	case language.Japanese.String():
+		return locale_jp
+	case language.Korean.String():
+		return locale_ko
+	default:
+		return locale_en
+	}
+}
+
+func getPrefferedLang(acceptLangHeader string) string {
+	matcher := language.NewMatcher(supportedLangs)
+	userPrefs, _, err := language.ParseAcceptLanguage(acceptLangHeader)
+	if err != nil {
+		// if error occurs, fallback to English
+		return language.English.String()
+	}
+	tag, _, _ := matcher.Match(userPrefs...)
+	base, _ := tag.Base()
+	return base.String()
+}
+
+var supportedLangs = []language.Tag{
+	language.English,  // en - first language is fallback
+	language.Chinese,  // zh
+	language.Japanese, // jp
+	language.Korean,   // ko
+}
+
+var locale_en = map[string]string{
+	"": "",
+}
+
+var locale_zh = map[string]string{
+	"": "",
+}
+
+var locale_jp = map[string]string{
+	"": "",
+}
+
+var locale_ko = map[string]string{
+	"": "",
+}

pkg/server/login/login.go

@@ -63,6 +63,8 @@ type LoginForm struct {
 
 	Names  LoginFormFields
 	Values LoginFormFields
+
+	Locale map[string]string
 }
 
 type LoginFormFields struct {
@@ -128,6 +130,8 @@ func (l *Login) handleLoginForm(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
+	form.Locale = getLocale(getPrefferedLang(req.Header.Get("Accept-Language")))
+
 	form.ErrorCode = req.URL.Query().Get(reasonParam)
 	if len(form.ErrorCode) > 0 {
 		if msg, hasMsg := errorMessages[form.ErrorCode]; hasMsg {