How to Make a Ruby Gem – A Developer's DevOps Perspective
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Fion L

Fion L @fionl

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How to Make a Ruby Gem – A Developer's DevOps Perspective

Publish Date: Jul 8
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Learn how to create and publish your own Ruby gem, from skeleton generation to deploying on RubyGems.org, with a focus on the DevOps approach.

As a software developer, it's easy to find ourselves constantly building apps—web apps, mobile apps, admin dashboards—but creating a Ruby gem is a whole different game.

It’s not just an exercise in programming, but also a challenge in packaging, documentation, testing, and deployment. In this post, I’ll walk you through how I started developing a Ruby gem, with a special focus on the DevOps pipeline and publishing to RubyGems.org. This guide will grow with time, as the gem matures, so feel free to comment and contribute!

Why Build a Ruby Gem?

This project is both personal and professional. It’s a chance to step beyond app development into the world of software tooling and libraries—creating code that can be reused and extended by other developers in the Ruby community.

Building a gem is also a fantastic way to understand how Ruby projects are structured, versioned, tested, and published, which is a core skill for any serious backend or full-stack developer.

Whether you want to open-source your gem, use it across multiple projects, or simply understand how bundler, versioning, and packaging work in Ruby, this is a great learning journey.

Step 1: Prepare Your Development Environment

Before diving in, you need to have Ruby and Bundler installed on your system.

Install bundler (if not already installed):

gem install bundler
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This installs the Bundler CLI globally, so you can now use it to generate new gems and manage dependencies.

Step 2: Generate the Gem Skeleton

You can now generate your gem’s scaffold using Bundler:

bundle gem your_gem_name
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This command sets up a project structure including:

  • A lib/ folder where your main code goes
  • A .gemspec file which describes your gem
  • A Gemfile to manage development dependencies
  • A README.md, a Rakefile, and test setup (RSpec or Minitest)

Keep it organized—your main file should live in lib/your_gem_name.rb.

Step 3: Create a GitHub Repository

Now it’s time to version control your project. Start by creating a new GitHub repository and then connect your local gem folder:

git init
git remote add origin https://github.com/your_username/your_gem_name_gem.git
git add .
git commit -m "Initial commit"
git push -u origin main
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This gives your gem a public home and enables collaboration, issue tracking, and documentation hosting.

Step 4: Set Up Your RubyGems.org Account

To publish your gem, you’ll need an account on RubyGems.org.

After signing up, RubyGems will provide a command like this:

curl -u your_username https://rubygems.org/api/v1/api_key.yaml > ~/.gem/credentials
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Run this in your terminal. It will save your RubyGems credentials securely.

Set proper permissions:

chmod 0600 ~/.gem/credentials
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Step 5: Understand the .gemspec File

Your gem’s .gemspec file is its identity card. It defines metadata such as:

  • name
  • version
  • authors
  • summary and description
  • files to include
  • Any required dependencies

Here’s a simplified snippet:

spec.name          = "your_gem_name"
spec.version       = YourGemName::VERSION
spec.summary       = "A simple tool to do XYZ"
spec.description   = "This gem helps developers do XYZ in a clean and efficient way."
spec.authors       = ["Your Name"]
spec.files         = Dir["lib/**/*.rb"]
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Make sure spec.files includes all the files needed for your gem to work properly.

Step 6: Build the Gem Locally

Once your code is ready and the .gemspec file is filled out, build the gem locally:

gem build your_gem_name.gemspec
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This will create a .gem file, which is a packaged version of your code.

Step 7: Push the Gem to RubyGems.org

Time to publish:

gem push your_gem_name-x.y.z.gem
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Once pushed, your gem will be available at:

https://rubygems.org/gems/your_gem_name
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Anyone can now install it using:

gem install your_gem_name
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Or include it in their Gemfile:

gem 'your_gem_name'
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Step 8: Gemfile vs. Gemfile.lock

Let’s clarify these two files:

  • Gemfile — declares your project’s gem dependencies
  • Gemfile.lock — freezes those dependencies to specific versions

When you run:

bundle install
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It creates or updates the Gemfile.lock. You can think of it like a balance sheet snapshot of your gem’s dependencies.

⚠️ Do not edit Gemfile.lock manually. Use bundle update to manage locked versions.

Bonus: Development Best Practices

  • ✅ Write tests (RSpec or Minitest) from the beginning
  • ✅ Use semantic versioning
  • ✅ Keep your README and inline documentation updated
  • ✅ Use rake release to automate tagging and gem publishing
  • ✅ Treat your gem like a product: maintain it well

Conclusion & What’s Next

This guide focused on the DevOps essentials for building and deploying a Ruby gem. You’ve learned how to:

  • Set up a gem project
  • Publish it to RubyGems
  • Understand its structure and versioning
  • Use Git and GitHub for open-source development

In the next blog post, I’ll cover the actual purpose of the gem, how I’m implementing its functionality, and how I plan to test and maintain it long-term.

Want to contribute or share your gem journey? Leave a comment or open a GitHub issue. Let’s build better Ruby tools—together. 🚀

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