I am using kong 0.13.1. Is there any documentation available to integrate OAUTH Authorization Code flow in a service instead of APIs.
You only need to enable the plugin on a Service entity instead of an API entity: this is an example from the documentation using a Service:
Configure this plugin on a Service by making the following request:
$ curl -X POST http://kong:8001/services/{my_service}/plugins \
--data "name=oauth2" \
--data "config.scopes=email,phone,address" \
--data "config.mandatory_scope=true" \
--data "config.enable_authorization_code=true"
More about it here: https://docs.konghq.com/plugins/oauth2-authentication/