new post: Load your config into your environment

_posts/2016-03-04-load-your-config-into-your-environment.mdv

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+---
+layout: post
+title: Load your config into your environment
+date: 04.03.2016 12:30
+---
+
+It became quite popular to store certain configuration variables in your environment, to be later loaded by your aplication.
+This way of [having all configuration](config) available is part of the [twelve-factor app definition][12factor].
+
+The idea is to place your variables in a `.env` file and load this as environment variables to be accessed by your application.
+Most of the time you can just plug in one of the dozens of libraries that load this config from a file and your application can fetch the values as normal from the environment.
+
+But sometimes you might want to have this config loaded into your shell or some other interactive tool.
+That's where you can use `dotenv-shell`, a small tool, written in Rust.
+It wraps around [rust-dotenv][dotenv] and allows to load the config and then execute a program (your shell by default).
+
+First install the tool:
+
+~~~
+cargo install dotenv-shell
+~~~
+
+Create a `.env` file with your config:
+
+~~~
+echo "REDIS_URL=redis://localhost:6379" > .env
+~~~
+
+Then start a shell and you can access the configuration as environment variables:
+
+~~~
+$ dotenv-shell
+$ echo $REDIS_URL
+redis://localhost:6379
+~~~
+
+Of course you can launch whatever tool you want:
+
+~~~
+$ dotenv-shell /usr/bin/irb
+irb(main):001:0> ENV['REDIS_URL']
+=> "redis://localhost:6379"
+~~~
+
+[Available on GitHub][repo] and [as a Crate][crate].
+
+[12factor]: http://12factor.net/
+[config]: http://12factor.net/config
+[dotenv]: https://github.com/slapresta/rust-dotenv
+[repo]: https://github.com/badboy/dotenv-shell
+[crate]: https://crates.io/crates/dotenv-shell