Your first config

Create a config from a Python dictionary, use string interpolation, and merge configs. You can run each example in a Python interpreter with OmegaConf installed.

By the end: you'll have a merged config that preserves a default, changes another value, and adds a new setting while the original stays unchanged.

1. Create a config

OmegaConf.create() turns a dictionary into a config.

>>> from omegaconf import OmegaConf
>>> config = OmegaConf.create({
...     "host": "localhost",
...     "port": 80,
...     "url": "http://${host}:${port}",
... })

2. String interpolation

The url value uses string interpolation: ${host} and ${port} reference other values in the config. OmegaConf resolves these references when you access url:

>>> config.url
'http://localhost:80'

3. Merge configs

OmegaConf.merge() takes one or more configs or dictionaries. Later values win when the same key appears more than once.

>>> # Merge a different port and a new debug setting.
>>> merged = OmegaConf.merge(config, {"port": 8080, "debug": True})
>>> # The interpolation uses the merged port.
>>> merged.url
'http://localhost:8080'
>>> # The merged config includes the new setting.
>>> merged.debug
True
>>> # The original config is unchanged.
>>> config.url
'http://localhost:80'

The merged config keeps host from the original, replaces port, and adds debug. The interpolated url automatically uses the new port, while the original config remains unchanged.

Dictionary configs also support | and |=. Use config | {"port": 8080, "debug": True} to create a merged config, or config |= {"port": 8080, "debug": True} to merge into the existing config. See Merge configs for details.

Continue with config containers to learn how to change nested values and work with sequences.