DotEnv-Conf

The dotenv_conf (.env configuration reader) crate is a .env reader that allows you to get strongly typed configuration information from a .env file, the process' environment, or from command-line args.

It comprises of two structs. The first (ConfReader) is configured with which sources to read from, and the second (ConfVal) is a builder that for configuring options of what keys to use to get values and methods to parse the data retrieved to strongly typed values.

The ConfVal methods for retrieving strongly typed data all return a Result of either the requested type of a String containing a reason why this key could not be provided. Reasons include:

• The key was not found in the configured sources.
• No value was provided for the requested key.
• The value could not be parsed to the requested type.

Example

use dotenv_conf::{ConfReader, ConfVal, ConfSource};

struct Config {
    db_url: String,
    db_port: u16,
    db_uid: Option<String>,
    db_pwd: Option<String>,
}

fn read_config() -> Result<Config, String> {
  let rdr = ConfReader::default();

  let config = Config {
    db_url: ConfVal::new("DB_URL").as_string(&rdr)?,
    db_port: ConfVal::new("PORT").cmd_line_key("db-port").as_u16(&rdr)?,
    db_uid: ConfVal::new("DB_USER_NAME")
      .cmd_line_key("user")
      .cmd_line_short_arg("u")
      .as_string_option(&rdr),
    db_pwd: ConfVal::new("DB_PASSWORD").cmd_line_key("pwd").as_string_option(&rdr),
  };

  Ok(config)
}

Notice

• The return type of the read_config method.
• The use of command line argument names, both long and short, and without their preceding dashes.
• The as_* methods that convert the found value to a strongly typed value or an option of that value.