Enum ConfigLayer 

pub enum ConfigLayer {
    File(PathBuf),
    EnvPrefix(String),
    Overrides(BTreeMap<String, Value>),
}

One named source of configuration values.

Layers are applied by ConfigBuilder::layer in the order they are added. A later layer’s keys replace earlier ones, while tables merge key-by-key (deep merge), so a late layer can override a single nested field without clobbering its siblings. Driven in the documented order this yields precedence overrides > env > file.

Variants

File(PathBuf)

A configuration file, parsed at load time by extension: .json (feature json), .yaml/.yml (feature yaml), and anything else — including no extension — as TOML.

EnvPrefix(String)

All environment variables sharing a prefix. The prefix is stripped and the remainder lowercased to form the top-level key; values are typed by inference (see the crate root for the exact rules).

Overrides(BTreeMap<String, Value>)

In-process values, typically assembled by a supervisor or test. Applied last in the documented order, hence highest precedence.

Implementations

impl ConfigLayer

pub fn file(path: impl AsRef<Path>) -> Self

A file-backed layer parsed by extension (TOML core; JSON and YAML behind the matching features).

pub fn env_prefix(prefix: impl Into<String>) -> Self

An environment layer matching every variable that starts with prefix (case-sensitive).

pub fn overrides(overrides: BTreeMap<String, Value>) -> Self

An in-process override layer keyed by top-level field name.

Trait Implementations

impl Clone for ConfigLayer

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ConfigLayer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.