`InterpolationKeyError`: Cannot use basic variable interpolation

🐛 Bug

Description

Running into an issue trying to use variable interpolation in the most basic case.

Checklist

• I checked on the latest version of Hydra
• I created a minimal repro (See this for tips).

To reproduce

### dataset.yaml ###
dataset:
    cwd: ${hydra:runtime.cwd}
    data_dir: ../${cwd}/data

### From testing_configs.py ###
print(cfg['dataset'].data_dir)

which produces the following:

...
raise InterpolationKeyError(f"Interpolation key '{inter_key}' not found")
omegaconf.errors.InterpolationKeyError: Interpolation key 'cwd' not found

Expected Behavior

I expect the path to be correctly printed:

/path/to/cwd/data/

System information

• Hydra Version : 1.2.0 / omegaconf==2.2.3
• Python version : 3.8.13
• Virtual environment type and version : conda (used pip install hydra-core —upgrade)
• Operating system : macOS 12.6

Additional context

I’m using a dataclass spec file with a ConfigStore instance.

Side note:

Why do I need the import statement from folder.file import Dataset in testing_configs.py file? I get a NameError otherwise.

[Jasha10]

You’ll probably need ${.cwd}/../.. to get two levels up, not ../${.cwd}.

If ${.cwd} is /foo/bar/baz then ${.cwd}/../.. will be equivalent to /foo/bar/baz/../.. while ../${.cwd} is equivalent to ..//foo/bar/baz (which is probably not what you want).

import os

from omegaconf import OmegaConf

OmegaConf.register_new_resolver(
    "abspath", lambda relative_path: os.path.abspath(relative_path)
)

yaml_data = """
### dataset.yaml ###
dataset:
    cwd: /foo/bar/baz
    data_dir_relative: ${.cwd}/../../data
    data_dir_absolute: ${abspath:${.cwd}/../../data}
"""

cfg = OmegaConf.create(yaml_data)
assert cfg.dataset.data_dir_relative == "/foo/bar/baz/../../data"
assert cfg.dataset.data_dir_absolute == "/foo/data"

[jonathanloganmoran]

That’s awesome! Thanks so much for helping me understand this — everything works perfectly!