Struct smart_config::ConfigRepository

pub struct ConfigRepository<'a> { /* private fields */ }

Configuration repository containing zero or more configuration sources. Sources are preprocessed and merged according to the provided ConfigSchema.

Merging sources

Self::with() merges a new source into this repo. The new source has higher priority and will overwrite values defined in old sources, including via parameter aliases.

Type coercion

When processing ConfigSources, values can be coerced depending on the expected type at the corresponding location as indicated by the param deserializer. Currently, coercion only happens if the original value is a string.

• If the expected type is BasicTypes::INTEGER, BasicTypes::FLOAT, or BasicTypes::BOOL, the number / Boolean is parsed from the string. If parsing succeeds, the value is replaced.

Coercion is not performed if the param deserializer doesn’t specify an expected type.

This means that it’s possible to supply values for structured params from env vars without much hassle:

use smart_config::{testing, DescribeConfig, DeserializeConfig, Environment};

#[derive(Debug, DescribeConfig, DeserializeConfig)]
struct CoercingConfig {
    flag: bool,
    ints: Vec<u64>,
    map: HashMap<String, u32>,
}

let mut env = Environment::from_iter("APP_", [
    ("APP_FLAG", "true"),
    ("APP_INTS__JSON", "[2, 3, 5]"),
    ("APP_MAP__JSON", r#"{ "value": 5 }"#),
]);
// Coerce `__json`-suffixed env vars to JSON
env.coerce_json()?;
// `testing` functions create a repository internally
let config: CoercingConfig = testing::test(env)?;
assert!(config.flag);
assert_eq!(config.ints, [2, 3, 5]);
assert_eq!(config.map, HashMap::from([("value".into(), 5)]));

Other preprocessing

Besides type coercion, sources undergo a couple of additional transforms:

• Garbage collection: All values not corresponding to params or their ancestor objects are removed.
• Hiding secrets: Values corresponding to secret params are wrapped in opaque, zero-on-drop wrappers.

Implementations

impl<'a> ConfigRepository<'a>

pub fn new(schema: &'a ConfigSchema) -> Self

Creates an empty config repo based on the provided schema.

pub fn schema(&self) -> &'a ConfigSchema

Returns the wrapped configuration schema.

pub fn deserializer_options(&mut self) -> &mut DeserializerOptions

Accesses options used during serde-powered deserialization.

pub fn with<S: ConfigSource>(self, source: S) -> Self

Extends this environment with a new configuration source.

pub fn with_all(self, sources: ConfigSources) -> Self

Extends this environment with a multiple configuration sources.

pub fn sources(&self) -> &[SourceInfo]

Provides information about sources merged in this repository.

pub fn iter(&self) -> impl Iterator<Item = ConfigParser<'_, ()>> + '_

Iterates over parsers for all configs in the schema.

pub fn single<C: DeserializeConfig>(&self) -> Result<ConfigParser<'_, C>>

Returns a parser for the single configuration of the specified type.

Errors

Errors if the config is not a part of the schema or is mounted to multiple locations.

pub fn get<'s, C: DeserializeConfig>( &'s self, prefix: &'s str, ) -> Option<ConfigParser<'s, C>>

Gets a parser for a configuration of the specified type mounted at the canonical prefix. If the config is not present at prefix, returns None.

Trait Implementations

impl<'a> Clone for ConfigRepository<'a>

fn clone(&self) -> ConfigRepository<'a>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'a> Debug for ConfigRepository<'a>

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

Formats the value using the given formatter.