Config containers

OmegaConf.create() with no argument makes an empty DictConfig. A dictionary also becomes a DictConfig, while a list becomes a ListConfig. These containers can be nested. Each key or list position is a node, but reading it gives you its value. For example:

>>> from omegaconf import OmegaConf
>>> cfg = OmegaConf.create({
...     "server": {
...         "host": "localhost",
...         "port": 80,
...     },
...     "users": ["a", "b"],
... })
>>> cfg.server.port
80
>>> cfg["server"]["port"]
80
>>> cfg.users[0]
'a'

Use attribute access for keys that work as Python attributes. Item access also works for other keys and for list positions. You can change a value or add a key to a DictConfig created from a plain dictionary:

>>> cfg.server.port = 8080
>>> cfg.server["public-host"] = "example.org"
>>> cfg.server["public-host"]
'example.org'

Use .get("key", default) when a mapping key may not exist. To pass a config to code expecting plain Python containers, use OmegaConf.to_container().

Dictionary keys may be str, int, bool, float, bytes, or Enum members.

Sequence containers

Lists become mutable ListConfig values. In 2.3, native tuples also become mutable ListConfig values. This changes in OmegaConf 2.4.

Next, learn how to mark a value as missing when it must be provided later.