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//! # Overview
//! This crate allows you to load .env files in your compilation step.
//! It is built to be used in your **[build.rs](https://doc.rust-lang.org/cargo/reference/build-scripts.html)** file.
//!
//! # Usage
//!
//! 1. Ensure you have build scripts enabled via the `build` configuration in your `Cargo.toml`
//! 1. Add `dotenv-build` as a build dependency
//! 1. Create a `build.rs` file that uses `dotenv-build` to generate `cargo:` instructions.
//! 1. Use the [`env!`](std::env!) or [`option_env!`](std::option_env!) macro in your code
//!
//! ### Cargo.toml
//! ```toml
//! [package]
//! #..
//! build = "build.rs"
//!
//! [dependencies]
//! #..
//!
//! [build-dependencies]
//! dotenv-build = "0.1"
//! ```
//!
//! ### build.rs
//! ```
//! // in build.rs
//! fn main() {
//! dotenv_build::output(dotenv_build::Config::default()).unwrap();
//! }
//! ```
//!
//! ### Use in code
//! ```ignore
//! println!("Your environment variable in .env: {}", env!("TEST_VARIABLE"));
//! ```
//!
//! [build scripts]: https://doc.rust-lang.org/cargo/reference/build-scripts.html
//! [cargo:rustc-env]: https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-env
//! [cargo:rerun-if-changed]: https://doc.rust-lang.org/cargo/reference/build-scripts.html#rerun-if-changed
//!
//! ### Configuration
//!
//! Read more about the available options here: [`Config`]
//! ```
//! let config = dotenv_build::Config {
//! filename: std::path::Path::new(".env.other"),
//! recursive_search: false,
//! fail_if_missing_dotenv: false,
//! ..Default::default()
//! };
//!
//! dotenv_build::output(config).unwrap();
//! ```
//!
//! ## Multiple files
//! Use [`output_multiple`] for this:
//!
//! ```
//! use std::path::Path;
//!
//! use dotenv_build::Config;
//!
//! let configs = vec![
//! // load .env.base
//! Config {
//! filename: Path::new(".env.base"),
//! // fail_if_missing_dotenv: true,
//! ..Default::default()
//! },
//! // load .env.staging
//! Config {
//! filename: Path::new(".env.staging"),
//! ..Default::default()
//! },
//! // load .env
//! Config::default(),
//! ];
//!
//! dotenv_build::output_multiple(configs).unwrap();
//! ```
mod errors;
mod find;
mod iter;
mod parse;
use std::io;
use std::io::Write;
use std::path::Path;
use crate::errors::*;
/// Config for [`output`]
pub struct Config<'a> {
/// The filename that is getting read for the environment variables. Defaults to `.env`
pub filename: &'a Path,
/// This specifies if we should search for the file recursively upwards in the file tree.
/// Defaults to `true`.
pub recursive_search: bool,
/// This specifies if we should return an error if we don't find the file. Defaults to `false`.
pub fail_if_missing_dotenv: bool,
}
impl<'a> Default for Config<'a> {
fn default() -> Self {
Config {
filename: Path::new(".env"),
recursive_search: true,
fail_if_missing_dotenv: false,
}
}
}
/// Outputs the necessary [build.rs](https://doc.rust-lang.org/cargo/reference/build-scripts.html) instructions.
///
/// ## Example
///
/// ```
/// dotenv_build::output(dotenv_build::Config::default()).unwrap();
/// ```
///
/// _.env_:
/// ```text
/// RUST_LOG=debug
/// RUST_BACKTRACE=1
///
/// ## comment
/// TEST="hello world!"
/// ANOTHER_ONE=test
/// ```
///
/// _output_:
/// ```text
/// cargo:rustc-env=RUST_LOG=debug
/// cargo:rustc-env=RUST_BACKTRACE=1
/// cargo:rustc-env=TEST=hello world!
/// cargo:rustc-env=ANOTHER_ONE=test
/// cargo:rerun-if-changed=$PATH_TO_YOUR_FILE/.env
/// ```
pub fn output(config: Config) -> Result<()> {
output_write_to(config, &mut io::stdout())
}
/// Same as [`output`] but to read multiple files
///
/// ## Example
///
/// ```
/// use std::path::Path;
///
/// use dotenv_build::Config;
///
/// let configs = vec![
/// // load .env.base
/// Config {
/// filename: Path::new(".env.base"),
/// // fail_if_missing_dotenv: true,
/// ..Default::default()
/// },
/// // load .env.staging
/// Config {
/// filename: Path::new(".env.staging"),
/// ..Default::default()
/// },
/// // load .env
/// Config::default(),
/// ];
///
/// dotenv_build::output_multiple(configs).unwrap();
/// ```
pub fn output_multiple(configs: Vec<Config>) -> Result<()> {
for config in configs {
output_write_to(config, &mut io::stdout())?;
}
Ok(())
}
fn output_write_to<T>(config: Config, stdout: &mut T) -> Result<()>
where
T: Write,
{
let (path, lines) = match find::find(&config) {
Ok(res) => res,
Err(err) if err.not_found() => {
return if config.fail_if_missing_dotenv {
eprintln!("[dotenv-build] .env file not found, err: {}", err);
Err(err)
} else {
Ok(())
};
}
Err(err) => return Err(err),
};
for line in lines {
let (key, value) = match line {
Ok(l) => l,
Err(err) => {
eprintln!("[dotenv-build] {}", err);
return Err(err);
}
};
writeln!(stdout, "cargo:rustc-env={}={}", key, value)?;
}
writeln!(stdout, "cargo:rerun-if-changed={}", path.to_str().unwrap())?;
Ok(())
}