feat(config): add default JWK URL for JWT validation

Author: tomondre

reana_server/config.py

@@ -302,6 +302,9 @@ def _get_rate_limit(env_variable: str, default: str) -> str:
 OAUTHCLIENT_REMOTE_APPS = dict()
 OAUTHCLIENT_REST_REMOTE_APPS = dict()
 
+# Default value for when no login providers are configured. Used for JWT validation.
+REANA_OAUTH_JWK_URL = None
+
 # Keycloak is only configured if login providers are defined
 if REANA_SSO_LOGIN_PROVIDERS:
     # Variables for the first login provider in the JSON