Include YAML config file

[fissoreg]

We need a configuration file where to specify the Huggingface/JinaHub model and other parameters (e.g. the directory where to store the embeddings, currently hardcoded).

There's already a backend_config.py file for the purpose. It works and the intent is clear, but it's maybe not the most orthodox way to deal with configurations. As Jina does, we could add a YAML file for configurations. @georgeamccarthy ?

[georgeamccarthy]

Good idea, relevant links:

• https://jina.ai/2021/03/09/yaml-intellisense-in-jina-app-development.html
• https://github.com/jina-ai/jina/blob/master/.github/2.0/cookbooks/Executor.md#with-yaml

[georgeamccarthy]

This would work well if we use Executors from the Hub.

[Rubix982]

Where would we like to integrate the YAML file configurations? Sadly not possible with Dockerfiles at this moment, but what configurations from the backend can we put into a YAML file?

[fissoreg]

Basically the backend_config.py can be turned into a backend_config.yml and moved out of src into backend.

[georgeamccarthy]

@Rubix982 here's some depreciated (Jina 1.0) docs on YAML https://docs1.jina.ai/chapters/yaml/. I believe somewhat similar concepts still apply.