Resolver interpolation

Node interpolation references another value in the config. Resolver interpolation uses ${name:arguments} to call a named resolver, a Python callable that computes a value. OmegaConf resolves the interpolation when you access its value.

For example, the built-in oc.env resolver reads an environment variable:

>>> import os
>>> from omegaconf import OmegaConf
>>> os.environ["OC_DOCS_COLOR"] = "blue"
>>> cfg = OmegaConf.create({"color": "${oc.env:OC_DOCS_COLOR}"})
>>> cfg.color
'blue'
>>> del os.environ["OC_DOCS_COLOR"]

Resolver arguments can themselves contain interpolations. Read the built-in resolver reference for available names and argument rules. To register your own Python function, see Write a custom resolver. Both node references and resolver interpolations can be resolved in place with OmegaConf.resolve().

Next, learn how structured configs validate values.