rust-dotenv

Achtung! This is an alpha version! Expect bugs and issues all around. Submitting pull requests and issues is highly encouraged!

Quoting bkeepers/dotenv:

Storing configuration in the environment is one of the tenets of a twelve-factor app. Anything that is likely to change between deployment environments–such as resource handles for databases or credentials for external services–should be extracted from the code into environment variables.

This library is meant to be used on development or testing environments in which setting environment variables is not practical. It loads environment variables from a .env file, if available, and mashes those with the actual environment variables provided by the operative system.

Usage

The aim of this project is to be as close as possible to a drop-in replacement for std::os::env. Because of this, the API exposed by the standard library is imitated. The methods provided by a Dotenv struct, env, env_as_bytes, getenv and getenv_as_bytes, carry the same signatures as their standard library counterparts.

Dotenv implements the dotenv static method, returning a Dotenv struct using the contents of the file named .env at the path of your application binary, if it exists. If you need finer control about the source of the environment variables, Dotenv exposes the static methods from_path, from_file, from_filename, from_bytes and from_str.

Examples

A .env file looks like this:

REDIS_ADDRESS=localhost:6379
MEANING_OF_LIFE=42

A sample project using Dotenv would look like this:

extern crate dotenv;

use dotenv::Dotenv;

fn main() {
    let dotenv = Dotenv::dotenv();
    for (key, value) in dotenv.env().into_iter() {
        println!("key: {}, value: {}", key, value)
    }
}

Dotenv also implements the Default trait, which returns a Dotenv struct without any content of its own; that is, containing only the environment variables exported by the system. This makes it easy to ignore IO failures if the environment variable file can't be found:

let dotenv = Dotenv::from_filename("nonexisting.env").ok().unwrap_or_default();