Struct EnvVarSource

pub struct EnvVarSource { /* private fields */ }

A config value source that fetches values from environment variables

The source can be supplied with a prefix for environment variables by using with_prefix.

Environment variable names, are thus then constructed as PREFIX_COMPONENT_COMPONENT_COMPONENT

If there is no prefix then it’s just COMPONENT_COMPONENT_COMPONENT

i.e. If the source has a prefix of MYCONFIG and you requested a value with the key database::connection_string. The environment variable that is looked up would be MYCONFIG_DATABASE_CONNECTION_STRING

It is worth noting, however, that this scheme may cause conflicts as the key database::connection_string and database::connection::string would result in the same environment variable DATABASE_CONNECTION_STRING.

Implementations

impl EnvVarSource

pub fn new() -> Self

Creates an environment variable source

pub fn with_prefix<T: Into<String>>(prefix: T) -> Self

Creates an environment source with a given prefix to the environment variables name.

Trait Implementations

impl Source for EnvVarSource

type Error = VarError

The error type used by this Source

fn get_value(&self, key: &Key) -> Result<Option<Value>, Self::Error>

Gets a value from the source with the given key