feat(input): add FDB input class

[frazane]

Description

This PR introduces a new class to get input fields from FDB. For using it, one must specify some keys of the request as kwargs in the configuration, which are then completed/overridden by the keys (date, time, param, etc.) of the mars request for the data as specified in the checkpoint (just like in MarsInput). The FDB configuration can either be provided as additional key-value pairs, or as environment variables.

Example config

input:
    fdb:
      expver: 0001
      number: 0
      step: 0
      class: od
      levtype: sfc
      model: ICON-CH1-EPS
      stream: enfo
      type: ememb

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Issue Number

Code Compatibility

• I have performed a self-review of my code

Code Performance and Testing

• I have added tests that prove my fix is effective or that my feature works
• I ran the complete Pytest test suite locally, and they pass

Dependencies

• I have ensured that the code is still pip-installable after the changes and runs
• I have tested that new dependencies themselves are pip-installable.

Documentation

• My code follows the style guidelines of this project
• I have updated the documentation and docstrings to reflect the changes
• I have added comments to my code, particularly in hard-to-understand areas

Additional Notes

[b8raoult]

You do not need the "request_template" part. This will be more inline with the other inputs and datasets sources

[frazane]

You do not need the "request_template" part. This will be more inline with the other inputs and datasets sources

Hi @b8raoult, my understanding is that fdb requests must be fully specified (is that correct? this seems to be the case at least with our fdb setup). However, we do not get a fully specified request from the checkpoint alone, and some missing keys need to be completed somehow. A request template seemed like the most straightforward approach but if there is a better way we should discuss it.

[frazane]

Removed the request_template - now additional keys are passed as kwargs.

[HCookie]

Thanks, looks good.
@frazane Happy for this to be merged?

[frazane]

Yes. Thanks for the support!