I have a frontend instance (Angular app on nginx), which proxies calls to backend under a specific domain (let's say backend-app). Everything's easy when there is only one instance of both backend and frontend - I name the Service backend-app and DNS resolves to the correct backend Deployment.

Let's say I have another version of backend which I would like to test before merging to master. As nginx configuration of frontend instance is hardcoded to proxy to backend-api, creating another Service under the same name for a newer version of backend doesn't work.

I considered these options:

1. Making an environment variable and substituting domain name in nginx proxy configuration during runtime. This way I could be flexible about where do I want to route frontend calls to. Cons of this solution, as far as I have investigated, is that this approach beats the purpose of self-containment, that is, it becomes ambiguous what is the frontend's backend client and this type of configuration is prone to errors.
2. Creating different namespace every time I want to test things. While this allows spinning the whole stack without any problem or conflict, it seems to me that it's a huge overhead to create namespaces just for testing something once.
3. Having some fancy configurations combining labels and selectors. I couldn't think or find how to do it.

Any other opinions/suggestions you might have?