https://github.com/iboard/exconfig

A configuration cache for Elixir, reading from `Application.get_env` and `System.get_env`
https://github.com/iboard/exconfig

configuration elixir elixir-lang

Last synced: 2 months ago
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A configuration cache for Elixir, reading from `Application.get_env` and `System.get_env`

• Host: GitHub
• URL: https://github.com/iboard/exconfig
• Owner: iboard
• License: mit
• Created: 2019-04-28T10:26:28.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2021-08-17T09:26:46.000Z (over 3 years ago)
• Last Synced: 2024-10-15T17:16:48.498Z (3 months ago)
• Topics: configuration, elixir, elixir-lang
• Language: Elixir
• Homepage: https://hexdocs.pm/exconfig
• Size: 110 KB
• Stars: 5
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE.md

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README

        
# Exconfig

[![Documentation](https://img.shields.io/badge/docs-hexpm-blue.svg)](http://hexdocs.pm/exconfig/)

[![Documentation](https://travis-ci.com/iboard/data_source.svg?branch=master)](https://travis-ci.com/iboard/exconfig)

- [At Github](https://github.com/iboard/exconfig)

- [Hex](https://hex.pm/packages/exconfig)

## Context

Don't use ENV-settings for compile-time configuration. (Because it is

hard to maintain your environment-settings for different deployments.

Imagine you want to build a Docker-image for your Phoenix-application

and you use something like

```elixir

   plug SomePlug, config_value: System.get_env("SOME_KEY")

```

`plug` is a macro and therefore, `SOME_KEY` gets evaluated at

compile time. If `SOME_KEY` is customer-related, this setting

get's burned into the image and may surprisingly pop up at the

wrong customer's server.

The `Exconfig`-package will help you not to make this mistake.

Just use `Exconfig.get` instead of all your `Application.get_env`

and `System.get_env` calls. Because the cache-server of `Exconfig`

will not run at compile-time you'll get a compile-error if you

try to use System-envs from your busines-logic.

## Usage

The application starts a GenServer and caches configuration at run time.

Loading configuration happens in two steps where each step overwrites

eventually existing values from previous steps.

  - Application.get_env(:app, :key) default

  - System.get_env(:key) default

Once the value is cached it will be returned from the GenServer state

rather than re-reading it from the environment again.

Using `Exconfig.clear_cache!/0` will drop the cache and values will be

loaded again if being accessed later.

### Example:

    iex> value = Exconfig.get(:my_app, :foo, "bar" )

    "bar"

    iex> value = Exconfig.get(:env, :some_secret )

    nil

`Exconfig.get/3` will first lookup for :myapp/:foo in the Exconfig.Cache 

(a GenServer) and if not found load from `Application`, `System`, or

returns the default. The second example will read from env-var SOME_SECRET.

Because no default value is given, it will return `nil`

## configuration.log

`Exconfig.get/3` is a macro. At compile-time in any environment but `:prod`,

it will capture it's usage in a file. The file can be configured in `config.ex`

and defaults to `configuration.log`.

The File can be used as a template for a shell-script.

## Installation

[Available in Hex](https://hex.pm/packages/exconfig). The package can be installed

by adding `Exconfig` to your list of dependencies in `mix.exs`:

```elixir

def deps do

  [

    {:exconfig, "~> 0.2.0"}

  ]

end

```

Documentation can be generated with `mix docs` ([ExDoc](https://github.com/elixir-lang/ex_doc))

and is published at [https://hexdocs.pm/exconfig](https://hexdocs.pm/exconfig).