This is a Keycloak Plugin that adds a required action during login. The required action is activated if a user has more than one attribute of the configured attribute name, and the user is then required to choose under which attribute value they wish to log in.
The plugin is build as a Docker container containing only a single jar file named /module/keycloak-auth-multi-value.jar.
To install the plugin copy the file to /opt/keycloak/providers/keycloak-auth-multi-value.jar in your Keycloak installation.
After installation a new required action REQUIRED_ACTION_CHOOSE is installed in Keycloak. This should be enabled in
the Keycloak realm under Authentication.
Further, the Keycloak installation should be given the environment variable
required_action_choose_attribute_attribute_name: The name of the attribute the user should choose from. This should match the attribute name received from the IdP.