External database lookup in TF serving or part of the TF graph
I'd say that you could wrap the TF server in something like a flask app, which takes in a REST request, applies the additional logic (the DB lookup), and populates and sends a request to the TF server (either via HTTP or gRPC). I don't think it would be possible to do it as 'part of the TF graph'.
I have an tensorflow model that I'm planning to deploy using tensorflow serving for model inference. 
Just wondering if there is a way to add some custom logic after the service receives the request and before it goes to the tensorflow model. Specifically, I need a lookup step from an external database, that would enrich the data the application receives through the REST call. 
Alternatively, is that possible as part of the tensorflow graph?
It sounds like an overkill to create a separate service just for that, if it can be bundled in the serving layer.