Hiring guide for Elixir Releases Engineers

Elixir Releases Developer Hiring Guide

Elixir is a functional programming language designed by José Valim and first released in 2012. It is built on the Erlang VM and shares many of its features, including concurrency and fault tolerance. Elixir is designed to be a modern, flexible, and fun language that is easy to learn and use. Sources: * [Elixir Language Documentation](https://elixir-lang.org/docs/) * [Elixir Wikipedia Page](https://en.wikipedia.org/wiki/Elixir_(programming_language))

Ask the right questions secure the right Elixir Releases talent among an increasingly shrinking pool of talent.

First 20 minutes

General Elixir Releases app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Elixir Releases application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you describe the concept of Elixir Releases?
Elixir Releases is a mechanism to package Elixir applications into a self-contained directory that includes your application code, all of its dependencies, plus the whole Erlang Virtual Machine (VM) and runtime. Therefore, you have everything you need to run the application.
What are the main advantages of Elixir Releases?
Elixir Releases provide several benefits including simplified deployment, self-contained packages, configuration and application start-up simplification, and improved performance.
Describe the difference between hot and cold deployments in Elixir Releases.
Hot deployments allow you to deploy changes to your application without downtime, while cold deployments require stopping and starting the application. Hot deployments are more complex and require a deep understanding of Erlang/OTP.
How would you configure an Elixir Release?
You can configure an Elixir Release through mix.exs, in the project function, by defining a releases key. It accepts the version of the release and any runtime configuration.
What are the steps to generate a release in Elixir?
To generate a release, you need to increment the version number in your mix.exs file, then run mix release. This will compile and generate a release in the _build/dev/rel directory.
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What you’re looking for early on

Does the candidate have a deep understanding of Elixir and its ecosystem?
Is the candidate familiar with the process of creating Elixir releases?
Can the candidate effectively troubleshoot and debug Elixir applications?
How well does the candidate understand OTP (Open Telecom Platform)?

Next 20 minutes

Specific Elixir Releases development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you deploy an Elixir Release?
You can deploy an Elixir Release by copying the release to the target host and starting it there. You can also use tools like Docker or deployment platforms like Gigalixir or Heroku.
How would you handle database migrations in Elixir Releases?
You can handle database migrations by creating a module with a function that can be called from the command line. This function will use Ecto.Migrator to run the migrations.
What are some common challenges when working with Elixir Releases?
Some common challenges include handling configuration changes, managing dependencies, understanding how to upgrade releases, and ensuring compatibility with the Erlang runtime.
How would you handle configuration changes in a release?
You can handle configuration changes by using config providers, which are modules that expose a function for loading configuration. This allows you to modify the configuration at runtime.
Describe the difference between compile-time and runtime configuration in Elixir Releases.
Compile-time configuration is done at the time of compiling the release, while runtime configuration is done when the release is actually running. Runtime configuration is more flexible as it allows changes without recompiling.
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The ideal back-end app developer

What you’re looking to see on the Elixir Releases engineer at this point.

At this point, a skilled Elixir Releases engineer should demonstrate strong problem-solving abilities, proficiency in Elixir Releases programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Elixir Releases.

What does this simple Elixir code do?
IO.puts "Hello, World!"
This code prints the string 'Hello, World!' to the console.
What does this Elixir code do?
defmodule Math do
  def add(a, b) do
    a + b
This code defines a module named 'Math' with a function 'add' that takes two parameters and returns their sum.
What does this Elixir code do?
list = [1, 2, 3, 4, 5]
Enum.map(list, fn x -> x * 2 end)
This code creates a list of numbers and then uses the 'Enum.map' function to create a new list where each element is twice the value of the corresponding element in the original list.
What does this Elixir code do?
spawn(fn -> 1 + 2 end)
This code creates a new process that executes the function 'fn -> 1 + 2 end'. The 'spawn' function is used for creating new processes in Elixir, which is a way of achieving concurrency.

Wrap-up questions

Final candidate for Elixir Releases Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Elixir Releases application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you perform a hot upgrade of an Elixir Release?
To perform a hot upgrade, you need to generate an upgrade release with mix release --upgrade, and then use the release_handler in Erlang to unpack and apply the upgrade.
What are some best practices for working with Elixir Releases?
Some best practices include keeping configuration minimal, managing your dependencies carefully, understanding the deployment process, and testing your releases thoroughly before deployment.
How would you manage dependencies in an Elixir Release?
Dependencies are managed by the mix tool. They are defined in the mix.exs file and are bundled into the release when it is built.

Elixir Releases application related

Product Perfect's Elixir Releases development capabilities

Beyond hiring for your Elixir Releases engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Elixir Releases projects, and can engage in multiple capacities.