Configuration

Reserved keys

_type (str): Fully-qualified dotted path to a class to instantiate.
_func (str): Fully-qualified dotted path to a callable. The callable is returned, not invoked.
_args (list): Positional arguments for the constructor.
_instance (str): Instance tag used to disambiguate cache entries. If omitted, caching is keyed by the constructor spec hash instead.
_ref (str): Reference to a top-level entry (optionally with dotted attributes).
_deep (bool): If false, the resolver returns the dict as-is without recursion. The _deep key itself is stripped from the returned mapping.
_include (list): Include other config files at load time.
_entries (list): Use to define dict keys that are dynamically resolved.
_call (dict): Default method and arguments for the CLI. Contains optional keys method (str) and args (list). See Command-line interface.

Rules

_type and _func are mutually exclusive.
_ref must be the only key in its mapping.
_func must be the only key in its mapping.
_instance only applies to _type.
Non-reserved keys on a _type mapping are treated as kwargs.

YAML example

service:
  _type: "myapp.services.UserService"
  _args: ["primary"]
  db:
    _type: "myapp.db.Database"
    host: "localhost"
    port: 5432
  cache:
    _type: "myapp.cache.RedisCache"
    url: "redis://localhost:6379"

TOML example

[service]
_type = "myapp.services.UserService"
_args = ["primary"]

[service.db]
_type = "myapp.db.Database"
host = "localhost"
port = 5432

[service.cache]
_type = "myapp.cache.RedisCache"
url = "redis://localhost:6379"

References

database:
  _type: "myapp.db.Database"
  host: "localhost"

user_service:
  _type: "myapp.services.UserService"
  db: { _ref: "database" }

Dotted refs access attributes on the referenced object:

pool_size:
  _ref: "database.connection_pool.size"

Entries for non-string keys

If a dict key needs to be resolved (including references), use _entries:

map:
  _entries:
    - _key: { _ref: "some.key" }
      _value: 123