Extending hydra configs from multiple directories with hydra.searchpath

[dorotat-nv]

Hi! In my use cases, we have some dependencies between hydra configs for training different models - different config groups.

However, the configs may be located in different directories. I am wondering how to tackle it without the limitation of hydra.searchpath being allowed only in the primary config. Ie an example

config /A/conf/A.yaml - some base config
config /B/conf/B.yaml that uses as a default /A/conf/A.yaml with hydra.search.path = "/A/conf"
config /B/conf/B1.yaml that uses as a default /B/conf/B.yaml from the same folder
config /C/conf/C.yaml that uses as a default /B/conf/B.yaml with hydra.search.path = "/B/conf"
Hydra will process with no problems configs in (1) and (2) but throws errors at (3) and (4) since they contain inherited hydra.searchpath from the defaults configurations.

Ideally, I would like to come up with a solution that attaches hydra.searchpaths from the non-primary configs to the hydra.searchpath as this approach gives the most visibility to where the configs are located

[odelalleau]

I can't think of a really good solution to this problem -- besides making Hydra support setting hydra.searchpath in non-primary configs so as to dynamically update the search path during composition (but I have no idea how hard it would be to implement this).

Here are two potential workarounds:

1. Provide hydra.searchpath on the command-line (must contain all paths required to load all parent configs)
2. Create two versions of each config: one with hydra.searchpath (used when it is the primary config -- should list all search paths of parents as well) and one without (used when included from child configs)

None of these workarounds is really satisfying since they are somewhat cumbersome and require updating either the command line (option 1) or the config (option 2) for all children of a config whose search path is updated.

Edit: Note that in option 2 above you wouldn't duplicate the config, instead the config with hydra.searchpath would include the other one through the defaults list