Crate config

Config organizes hierarchical or layered configurations for Rust applications.

Config lets you set a set of default parameters and then extend them via merging in configuration from a variety of sources:

• Environment variables
• String literals in well-known formats
• Another Config instance
• Files in well known formats and custom ones defined with Format trait
• Manual, programmatic overrides

Additionally, Config supports:

• Live watching and re-reading of configuration files
• Deep access into the merged configuration via a path syntax
• Deserialization via serde of the configuration or any subset defined via a path

Example

use std::collections::HashMap;

use config::Config;

fn main() {
    let settings = Config::builder()
        // Add in `./Settings.toml`
        .add_source(config::File::with_name("examples/simple/Settings"))
        // Add in settings from the environment (with a prefix of APP)
        // Eg.. `APP_DEBUG=1 ./target/app` would set the `debug` key
        .add_source(config::Environment::with_prefix("APP"))
        .build()
        .unwrap();

    // Print out our settings (as a HashMap)
    println!(
        "{:?}",
        settings
            .try_deserialize::<HashMap<String, String>>()
            .unwrap()
    );
}

See more examples for general usage information.

Re-exports

pub use crate::builder::ConfigBuilder;

Modules

builder

Structs

Config

A prioritized configuration repository.

Environment

An environment source collects a dictionary of environment variables values into a hierarchical config Value type. We have to be aware how the config tree is created from the environment dictionary, therefore we are mindful about prefixes for the environment keys, level separators, encoding form (kebab, snake case) etc.

File

A configuration source backed up by a file.

FileSourceFile

Describes a file sourced from a file

FileSourceString

Describes a file sourced from a string

Value

A configuration value.

Enums

Case

Defines the type of casing a string can be.

ConfigError

Represents all possible errors that can occur when working with configuration.

FileFormat

File formats provided by the library.

ValueKind

Underlying kind of the configuration value.

Traits

AsyncSource

Describes a generic source of configuration properties capable of using an async runtime.

FileSource

Describes where the File is sourced

FileStoredFormat

An extension of Format trait.

Format

Describes a format of configuration source data

Source

Describes a generic source of configuration properties.

Type Aliases

Map

The backing store for Config