Overriding a default for config group from the command line, when the value is also defined in the config file.

[ysavtchouk-pf]

Hi all!

We have the following structure

config.yaml file - our root file
Contents:

defaults:
  - _self_
  - experiment: null

Experiment files:
configs/experiment/stage-one.yaml

Contents:

defaults:
  - /configuration_source: base

configuration_source:
  vmec_file_path: starfinder/inputs/input.nfp2_QA

Configuration source file:
configs/configuration_source/configuration1.yaml:

vmec_file_path: starfinder/inputs/input.nfp2_QA

I am trying to override the configuration_source with the command line

my-binary experiment=stage-one configuration_source=configuration1

However, this does not work, since vmec_file_path: starfinder/inputs/input.nfp2_QA has a priority.

If I instead define in configs/experiment/stage-one.yaml

defaults:
  - _self_
  - /configuration_source: base

configuration_source:
  vmec_file_path: starfinder/inputs/input.nfp2_QA

Then vmec_file_path: starfinder/inputs/input.nfp2_QA will always be overridden. E.g. running my-binary experiment=stage-one will take values from base.

I feel like I am missing something here. Is there a proper way to achieve that the user input takes precedence, still using config groups?

thank you in advance!

[odelalleau]

If I understand correctly, what you're trying to do is somewhat unusual, since the configuration_source=configuration1 that you want to provide on the command line should not behave the same as the configuration_source: ... in your config (because the latter is supposed to get overridden by the content of stage-one.yaml)

I'm not sure if there's a better way, but one workaround is to treat them as different config groups (since they are behaving differently). Something like this (not tested with your specific configs):

defaults:
  - /configuration_source: base
  - _self_
  - optional /configuration_source_override@configuration_source: null

configuration_source:
  vmec_file_path: starfinder/inputs/input.nfp2_QA

and then use on the command line configuration_source_override=configuration1.

You can do a ln -s configuration_source configuration_source_override to be able to re-use the exact same configs.

[ysavtchouk-pf]

This, unfortunately, still does not work:
hydra.errors.ConfigCompositionException: Could not override 'configuration_source_override'.

My goal is to provide have a way to pass config group name from the command line, but if nothing is passed on the command line, then use configuration_source from the experiment file.

If I don't include /configuration_source into defaults, then I can't do configuration_source=configuration1

[odelalleau]

I tried to replicate your exact setup, which seems to be like this:

.
├── conf
│   ├── config.yaml
│   ├── configuration_source
│   │   ├── base.yaml
│   │   └── configuration1.yaml
│   └── experiment
│       └── stage-one.yaml
├── my_app.py

but running

python my_app.py experiment=stage-one  configuration_source=configuration1

crashes, you need to use

python my_app.py experiment=stage-one  [email protected]_source=configuration1

and then as far as I can tell my suggestion works, it just becomes

python my_app.py experiment=stage-one  [email protected]_source=configuration1

(NB: the syntax would probably be a bit simpler if you moved configuration_source within experiment, I'm not sure exactly why you wanted to have it at the top-level config)

[ysavtchouk-pf]

Thanks! I actually think there is a better way to achieve what I want:
it seems that if there is no - /configuration_source: base in defaults, I can just pass

python my_app.py experiment=stage-one +configuration_source=configuration1

And it has priority over the value in config.

[odelalleau]

Yes indeed -- I had assumed you needed this configuration_source for your code to work as expected without a command-line override.