[Feature Request] Override loaded config file through a command line flag

🚀 Feature Request

I want to pass yaml file instead of parameters like foo.bar=1 ... to override default configuration:

$ python app.py --yaml foo.yaml

[jbohnslav]

Hi there,

I just wanted to +1 for this feature request. My use case is as follows. I have a complex configuration file with lots of details the user will not need to interact with, e.g. optimizers. There are elements, particularly regarding the data and augmentations, that all users will have to customize.

Default conf/config.yaml:

train
  lr: 0.0001
  optimizer: adam
dataset
  name: imagenet
  classes: 
    - tench
    - goldfish
    - great white shark
    - ... etc
augs
  resize: 224
  flip_lr: true
  flip_ud: false

user_config.yaml:

dataset
  name: not hotdog
  classes:
    - hotdog
    - not hotdog
augs
  resize: 64
  flip_lr: true
  flip_ud: true

What I want is to be able to use the following syntax and have Hydra load the default configuration file first, and optionally override with the user’s supplied config file: python train.py --config user_config.yaml

Ideally, the user could also supply command line arguments which would take precedence over all. I’m not sure if this is too unique to my use case. I want the priority to be command line args > user defaults from user_config.yaml > conf/config.yaml.

Is there a way to do this currently with hydra?

[SunQpark]

I’m currently using a workaround for a similar case.

Default conf/config.yaml:

user_config: # path to config file to update.
train:
  lr: 0.0001
  optimizer: adam
dataset:
  name: imagenet
  classes: 
    - tench
    ...

Then, in the train.py you can override hydra config object with OmegaConf.merge function when user_config is given.

if config.user_config is not None:
    user_config = OmegaConf.load(config.user_config)
    config = OmegaConf.merge(config, user_config)

Now, you can use python train.py user_config=user_config.yaml