Set Hydra enviroment with uvicorn/fastapi

Question

I have a FastAPI application that is going to production soon, however i am facing some problems with hydra integration.

First i could not run the @hydra.main() decorator on fastAPI endpoints. This was overcome with using the Hydra Compose API. Here is my implementation for it:

def load_config(config_path, config_name):
    """Loads specified hydra config.

    This method is used because, fastapi and hydra did not
    wanna work together.
    """
    core.global_hydra.GlobalHydra.instance().clear()
    initialize(version_base=None, config_path=config_path)
    cfg = compose(config_name=config_name)

    return cfg

This was fine until now, while I only used one config, but now I need to separate test and production configurations.
My configuration dircetory structure looks like this:

├── config
│   ├── config.yaml
│   ├── env
│   │   ├── prod.yaml
│   │   └── test.yaml
│   ├── prod
│   │   └── prod1.yaml
│   └── test
│       └── test1.yaml

The directory structure and file contents are based on this post: Python Hydra configuration for different environments. The default environment is set to test.

My application runs with this command: uvicorn my.api:app and this successfully loads the test config. However when I try to run it with: uvicorn env=prod my.api:app the test config still loads instead of production. Here i want to load the prod configuration. How can I achieve this? I have found this related github issue, but the solution was not clear from it: https://github.com/facebookresearch/hydra/issues/204

To be clear, i am willing to make fundamental changes if the problem lies within not using @hydra.main()

score 2 · Answer 1 · answered Jan 26 '23 at 18:44

The Compose API does not integrate with the command line. You need to pass the overrides yourself on the call site. Check the example in the Compose API page again, in particular the overrides parameter.

from hydra import compose, initialize
from omegaconf import OmegaConf

if __name__ == "__main__":
    # context initialization
    with initialize(version_base=None, config_path="conf", job_name="test_app"):
        cfg = compose(config_name="config", overrides=["db=mysql", "db.user=me"])
        print(OmegaConf.to_yaml(cfg))

Set Hydra enviroment with uvicorn/fastapi

1 Answers1