Building a Scalable REST API with Elixir and Phoenix: A Step-by-Step Guide

Building a Scalable REST API with Elixir and Phoenix

Elixir and the Phoenix framework are a powerful combination for building scalable and maintainable applications. In this article, we will explore the benefits of using Elixir and Phoenix, and provide a step-by-step guide on how to build a REST API.

What is Elixir?

Elixir is a functional, dynamically-typed language that is built on top of Erlang. It was created by Jose Valim, who worked on the Ruby on Rails team, and was designed to solve performance bottlenecks with Ruby on Rails and Erlang. Elixir is mainly used to create highly scalable applications that are fault-tolerant and easily maintainable.

Benefits of Elixir

Elixir has several key characteristics that make it an ideal choice for building great apps:

• Concurrency: Elixir uses process threads for execution, which are isolated, CPU-based, and communicate through messages.
• Scalability: Scaling an Elixir application is simple, as it uses lightweight threads that can run with few processes.
• Reliability: Building fault-tolerant applications is one of the main features of Elixir. When an Elixir application fails in production, the supervisor system restarts the lightweight process quickly, reducing downtime.

What is Phoenix?

Phoenix is a web framework in the Elixir ecosystem that comes with modules out-of-the-box to help build highly scalable and fault-tolerant applications. It is a Model-View-Controller (MVC) framework similar to Ruby on Rails and Django. One of the killer features of Phoenix is LiveView, a library that helps build real-time applications without writing client-side JavaScript.

How Phoenix Works

Phoenix receives an incoming request and converts it into a Conn data structure, which is then passed through several plugs to complete the functionality and return a response. The lifecycle of a Phoenix request is as follows:

1. Receives a request
2. Converts it to Conn
3. Passes through several plugs
4. Returns a response

Building a REST API with Elixir and Phoenix

Now that we have explored the benefits of Elixir and Phoenix, let’s build a REST API that delivers user information to a Postgres database. We will create a CRUD (Create, Read, Update, Delete) API with endpoints for users.

Prerequisites

Before you proceed, ensure you have the following prerequisites:

• Basic understanding of Elixir syntax
• Install Elixir on your machine
• Have Postgres installed on your machine
• Have the Postman client or an alternative to test APIs

Getting Started

First, install Elixir on your machine. For macOS, use Homebrew package manager:


brew update
brew install elixir


Next, install the Elixir package manager Hex:


mix local.hex


Verify the installation by checking the version:


elixir --version


Installing Phoenix

Install Phoenix using the following command:


mix archive.install https://github.com/phoenixframework/archives/raw/master/phx_new.ez


Create a new project using the Phoenix framework:


mix phx.new users_api --no-html --no-webpack --binary-id


This will create a users_api directory with the boilerplate for a Phoenix application.

Configuring the Database

Configure the database in the config/dev.exs file with Postgres database credentials:


config :users_api, UsersApi.Repo,
username: "postgres",
password: "postgres",
database: "users_api_dev",
hostname: "localhost",
show_sensitive_data_on_connection_error: true,
pool_size: 10


Create a database for the development environment:


mix ecto.create


Drop the database using:


mix ecto.drop


Defining the Schema

Define the schema for the users table using the following command:


mix phx.gen.schema Admin.User users \
id:uuid \
name:string \
email:string \
role:string \
address:string


This will create a lib/admin/user.ex file with the schema definition.

Running Migrations

Run the migration for the defined schema:


mix ecto.migrate


Scaffolding Controller and View

Generate the controller and view for the users module:


mix phx.gen.json Admin User users \
id:uuid \
name:string \
email:string \
role:string \
address:string --no-context --no-schema


This will create a lib/users_api_web/controllers/users_controller.ex file and a lib/users_api_web/views/users_view.ex file.

Adding Routes

Add routes for the users module in the lib/users_api_web/router.ex file:

“`
defmodule UsersApiWeb.Router do
use UsersApiWeb, :router

scope “/api”, UsersApiWeb do
pipe_through :api

resources "/users", UserController, except: [:new, :edit]

end
end
“`

Running the Application

Run the application using:


mix phx.server


Test the API using Postman or an alternative.

In this article, we have explored the benefits of using Elixir and Phoenix, and provided a step-by-step guide on how to build a REST API. With Elixir and Phoenix, you can build scalable and maintainable applications with ease.