3.8. Locale Selector
By default, the locale is selected using the DefaultLocaleSelectorProvider which implements the LocaleSelectorProvider interface. English is the default language when internationalization is disabled. With internationalization enabled, the locale is resolved in the following priority:
-
kc_localequery parameter -
KEYCLOAK_LOCALEcookie value - User’s preferred locale if a user instance is available
-
ui_localesquery parameter -
Accept-Languagerequest header - Realm’s default language
This behaviour can be changed through the LocaleSelectorSPI by implementing the LocaleSelectorProvider and LocaleSelectorProviderFactory.
The LocaleSelectorProvider interface has a single method, resolveLocale, which must return a locale given a RealmModel and a nullable UserModel. The actual request is available from the KeycloakSession#getContext method.
Custom implementations can extend the DefaultLocaleSelectorProvider in order to reuse parts of the default behaviour. For example to ignore the Accept-Language request header, a custom implementation could extend the default provider, override it’s getAcceptLanguageHeaderLocale, and return a null value. As a result the locale selection will fall back on the realms’s default language.
Follow the steps in Service Provider Interfaces for more details on how to create and deploy a custom provider.
