Скачать или смотреть Setting Your Environment Variable in Phoenix: A Step-by-Step Guide to configure Your Application

Discover how to effectively set an environment variable in Phoenix, ensuring your application works seamlessly in both `dev` and `prod` modes.
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Setting Your Environment Variable in Phoenix: A Step-by-Step Guide

When developing a web application with the Phoenix framework, you might find yourself needing to set environment variables that differ between your development (dev) and production (prod) environments. This is especially important when dealing with URLs or APIs that your application interacts with. In this guide, we’ll walk you through how to set these environment variables in Phoenix and how to ensure your code utilizes them effectively.

The Problem: Configuring URLs for Different Environments

Imagine you have a specific URL that you need your application to use, but this URL varies based on the environment:

In the development environment, the URL should be http://localhost:3000

In the production environment, it should change to https://www.foobar.com

To achieve this, you need to configure your application to access the correct URL based on the environment it's running in. Here are the steps to accomplish that.

Step 1: Setting the Environment Variable

Compile-Time Configuration

If you know that your URL is static and will not change often, you can set this environment variable in the configuration files. Here’s how you can do it:

Open your configuration files located in the config folder:

config/dev.exs for development

config/test.exs for testing

config/prod.exs for production

Add the URL configuration to each environment file:

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Runtime Configuration

If you want a more dynamic solution that allows you to adjust the variable at runtime, you will use runtime.exs. This method is useful if you need to change settings after building your application release.

Open or create the runtime.exs file in your config directory.

Set up the environment variable using System.get_env/1. For example:

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Make sure to set the EXTERNAL_SUPPORT_SITE environment variable in your hosting platform or local environment.

Step 2: Accessing the Environment Variable in Your Code

Now that we have our environment variable set up, we will learn how to utilize it in your application.

Updating the Controller

Here’s an example of how to redirect using the environment variable in your controller:

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In this snippet, the Application.get_env function retrieves the value of :external_support_site that we configured earlier. If for some reason it’s not set, it will fallback to a default URL of https://some-default.example.com.

Conclusion

Setting environment variables in your Phoenix application allows you to easily switch between different configurations for development and production. By following the above steps, you can ensure that your application redirects users to the correct URL based on the environment it is running in.

Key Takeaways

Use the config/*.exs files for compile-time configurations.

Opt for runtime.exs to set variables that may change after building a release.

Access these variables in your application using Application.get_env/3.

Now you’re all set to handle environment variables effortlessly in your Phoenix applications. Happy coding!