Book Image

Mastering Elixir

By : André Albuquerque, Daniel Caixinha
Book Image

Mastering Elixir

By: André Albuquerque, Daniel Caixinha

Overview of this book

Running concurrent, fault-tolerant applications that scale is a very demanding responsibility. After learning the abstractions that Elixir gives us, developers are able to build such applications with inconceivable low effort. There is a big gap between playing around with Elixir and running it in production, serving live requests. This book will help you fll this gap by going into detail on several aspects of how Elixir works and showing concrete examples of how to apply the concepts learned to a fully ?edged application. In this book, you will learn how to build a rock-solid application, beginning by using Mix to create a new project. Then you will learn how the use of Erlang's OTP, along with the Elixir abstractions that run on top of it (such as GenServer and GenStage), that allow you to build applications that are easy to parallelize and distribute. You will also master supervisors (and supervision trees), and comprehend how they are the basis for building fault-tolerant applications. Then you will use Phoenix to create a web interface for your application. Upon fnishing implementation, you will learn how to take your application to the cloud, using Kubernetes to automatically deploy, scale, and manage it. Last, but not least, you will keep your peace of mind by learning how to thoroughly test and then monitor your application.
Table of Contents (18 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
5
Demand-Driven Processing
Index

Connecting to the database


In the introduction, we hinted at how we'll use Ecto to store our application data in a PostgreSQL database. Ecto is able to connect to many databases, but for each database it needs the respective driver to establish the connection, support queries, and so on.

 

In our case we'll use the postgrex library, which provides the PostgreSQL Elixir driver. But don't think Ecto is tied to PostgreSQL in any way, because Ecto supports other databases like MySQL, DynamoDB, and SQLite, among others.

Let's start by adding the ecto and postgrex libraries to our elixir_drip umbrella app dependencies:

$ cat apps/elixir_drip/mix.exs
defmodule ElixirDrip.Mixfile do
  use Mix.Project

  defp deps do
    [
      {:postgrex, "~> 0.13"},
      {:ecto, "~> 2.1"},
      # ...
    ]
  end
end

These two dependencies will be fetched by mix as soon as we run mix deps.get. The next step consists of defining and configuring the Ecto repository. Every database operation passes through it,...