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 2.3 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.

OmegaConf 2.4 adds | to create a merged dictionary config and |= to merge into an existing one. These operators are unavailable in 2.3; see Merge configs in 2.4.

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