def init_app(self, app):
        """Configures the specified Flask app to enforce SSL."""
        app.config.setdefault("SSLIFY_SUBDOMAINS", False)
        app.config.setdefault("SSLIFY_PERMANENT", False)
        app.config.setdefault("SSLIFY_SKIPS", None)

        self.hsts_include_subdomains = (
            self.hsts_include_subdomains or app.config["SSLIFY_SUBDOMAINS"]
        )
        self.permanent = self.permanent or self.app.config["SSLIFY_PERMANENT"]
        self.skip_list = self.skip_list or self.app.config["SSLIFY_SKIPS"]

        app.before_request(self.redirect_to_ssl)
        app.after_request(self.set_hsts_header)