Installing Rails

In this project, we're going to build a fully functional Rails application.


If you went through the Ruby course you will have already installed Ruby. But if you haven't done that, then now is the time to install it as you will need Ruby installed before we tackle installing Rails.

With Ruby installed, you're all set to install Rails and create our first Rails app to ensure everything went smoothly.

Before continuing, let's review a few best practices to keep in mind:

  • Follow the directions closely, and don't skip over any sections.

  • Do NOT use sudo. Failing to follow this advice can cause a lot of headaches. In some instances, you might see a message in the terminal telling you to use sudo and/or to install something with apt. Ignore what the terminal says and follow the instructions below.

  • Copy and paste the commands to avoid typos.

  • If you stop working on this project partway through and come back to it later, be sure to use cd to move back inside your project directory so that the commands will work.

In this project, we're going to build a fully functional Rails application. The entire point of this exercise is to make sure that you have everything installed and working correctly on your computer. Do not worry if you don't fully understand what you're doing. You'll learn exactly what all of these commands are doing later on in the course. For now, go slowly, and be sure to follow each and every step closely.

Reminder: In this lesson you'll see shaded boxes that contain text like the one below.


Those are terminal commands and you'll need to enter them on the terminal in your operating system. Forgot how to open your terminal? Try googling "how to open terminal in [your operating system]".

Step 1: Create your first Ruby on Rails web application

Don't worry if you don't totally understand what you are doing in these next steps. You will learn what all of this does later in the curriculum. As long as the commands complete successfully, just keep going. The main reason we're doing this is to ensure everything is properly installed and configured.

Step 1.1: Install Rails

We've previously installed Ruby, and now it's time to install Ruby on Rails. It's as simple as running one command!

gem install rails

Once the installation finishes, you can check if everything went well by restarting your terminal and running the following command:

rails -v

This should display the version of Rails installed on your system indicating the installation went smoothly.

Step 1.2: Install yarn

With Rails 6 came Webpacker, a Ruby Gem that integrates Webpack, the Javascript module bundler, with Rails.

Javascript libraries used to be managed through the asset pipeline in Rails but as Javascript progressed it became a little dated and made it hard to integrate the latest Javascript libraries and frameworks.

Yarn is a Javascript package manager, much like Bundler for Ruby and allows you to easily manage your Javascript libraries.

Visit The Yarn Download Page and from the dropdown box choose the operating system you are using. It will then present you with instructions on how to install Yarn. Follow the instructions step by step.

You can verify the install by running the following command

yarn --version

If you don't get a version number drop by the chatrooms for some assistance.

You won't need to use Yarn for this tutorial but you do need it installed for Rails to set up Webpack correctly.

Step 1.3: Lay the groundwork

Next, if you haven't already done it, we need to create a directory that will house our project. You can name it anything you like!

mkdir im_on_rails

Then, move into the new directory:

cd im_on_rails

Step 1.4: Create the application

This is where things might start to be difficult to follow just what is happening. If you don't understand what's going on, just double check that you're typing in the correct commands and keep going. This section is meant to expose you to the process and to verify that everything is working. Again, it's OK to not understand what's going on at this point.

We're going to start by telling Rails to initialize the application for us. Then, we'll tell Rails to create a template for us so that we can get up and running.

rails new my_first_rails_app

This will do a bunch of things, and you'll see a lot of output in the terminal. If everything worked, you should see something similar to this in the last few lines of output:

Bundle complete! 18 Gemfile dependencies, 79 gems now installed.
Use `bundle info <gem name>` to see where a bundled gem is installed.

In the above process, Rails created a new directory for us. Let's cd into it now:

cd my_first_rails_app

Now, we're going to tell Rails to generate some templates for us. This will get us up and running in no time at all. If you are using Ruby 2.7 or higher then you may see some deprecation warnings that look like errors in the console. Ruby made some changes in version 2.7 to deprecate using hashes as the last argument of a method call. You can read more about it here. It will take time for gems to update their codebases to deal with this deprecation, especially if they are as large as Rails. If you do see any deprecation warnings then don't worry, they will get fixed eventually. The warnings will look something like:

warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call

Run the following in the terminal:

rails generate scaffold car make:string model:string year:integer

After generating the scaffolds, we need to migrate the database.

rails db:migrate

Step 1.5: Start up your app

Now that you have created a Rails application, you can start it up and see if it works!

In the terminal, type

rails server

Now, open a browser and visit http://localhost:3000/cars to see your application! Note: If you're using a VM, you will need to open the browser inside of your VM in order for this to work.

Go ahead and create a new car, and then refresh the page to verify it is working. Add as many cars as you'd like! When you're satisfied, go back to the terminal where the Rails server is running, and type Ctrl + C to close the server.

Step 2: Initialize Git and Push to GitHub

To push our app to GitHub and Heroku, we need to use Git.

Step 2.1: Initialize git

To tell Git we want to use version control on the directory we are in, we need to initialize it.

Verify you're in the my_first_rails_app directory by using the pwd (print working directory) command.

$ pwd

Then, initialize the Git repo (short for "repository"):

git init

Step 2.2: Commit changes

Now that Git is initialized, we need to tell Git to save all the files we have. First, we add our files to the staging area, which temporarily holds files before committing them. Don't worry if you don't understand all of this right now.

To stage all our files, type

git add .

Then, we'll commit the files. Be sure to include the quotation marks.

git commit -m "initial commit"

Step 2.3: Connect the local repository to the remote repository

At this point, we have our files on our own computer and can track changes made to our files over time. But what if we want to share the files with another computer or have multiple people work on the same project? For this functionality, we need a GitHub repository.

First, open in your browser and sign in (if you aren't already). Next, look for your profile picture in the upper right-hand corner, click the "+" symbol next to it, and then click New repository. Give the repository a name (maybe my_first_rails_app?), and make sure you do not initialise the repository with a README and Rails created one already. Click Create Repository.

On the next page, you'll see a bunch of commands listed. We're really only interested in the SSH URL at the top, so double check that SSH has been selected and then copy the URL.

Now, switch back over to the terminal to connect the project and GitHub by running two simple commands:

NOTE: Do not enter the < or > symbols. Replace those symbols and everything between them with the URL that you copied from GitHub.

git remote add origin <SSH URL from above>
git push -u origin main

Remember to replace <SSH URL from above> with the URL that you copied.

The terminal will start its work, pausing to verify your connection to GitHub.

A message from GitHub stating, "The authenticity of host ''..." may appear during this process. You can type yes and hit Enter to continue.

After the terminal finishes its magic, return to your GitHub repository and refresh the page. You should see a lot of files, starting with a folder called "app".

This marks the start of your journey! Later on, you'll be able to look back at this repository and marvel over how far you've come!

Step 3: Deploy your Rails application

Now that you've created your first Rails application, it's time to deploy it so that you can show the whole world! This process will allow you to send a link to people so they can see your app working.

Recall, in the previous lesson we set up our Heroku account to deploy our web applications. If you have not already done so, go back and complete the lesson.

Step 3.1: Create a Heroku application

First, run

heroku create

Then, run

git remote

Verify that you see heroku in the output.

Step 3.2: Prepare Rails for Heroku Deployment

Heroku uses a slightly different setup than what we have on our machine. We need to configure the application to play nicely with both.

Step 3.2.1: Configure the Gemfile

To deploy a Rails application, we need to change some settings.

First, we need to open the Gemfile and edit it.

In your terminal, type ls and verify that you see Gemfile in the output. If you don't see it, navigate to the directory you created in Steps 2.2 and 2.3.

Then, we'll use VSCode to modify the Gemfile. Open your app in VSCode by typing code . (NOTE: The period at the end is important!)

When VSCode opens, you should see a list of files on the left side of the screen. Click on Gemfile to open it in the editor. Then, delete the line that says,

gem 'sqlite3'

Replace the line you just deleted with the following:

group :development, :test do
  gem 'sqlite3'

group :production do
  gem 'pg'

Then, save the file. You can leave VSCode open since we're going to be coming back to it, but for the next step, go back to your terminal.

Step 3.2.2: Install the new gems.

Next, we need to tell Ruby, Git, and Heroku that we've changed the Gemfile. To do this, we can simply run

bundle install --without production

We use --without production here because the pg gem relies on having the pg database installed locally. Without it the gem can't build the native extensions needed to interact with the database. That is something we would definitely recommend but not at this stage. An sqlite database is much easier to get up and running for development.

Step 3.2.3: Configure the root route

The next thing we need to edit is the routes.rb file to set our root route. We're going to do this so that we can see the application without having to append /cars at the end of the URL.

Go back to VSCode and expand the config folder in the file list at the left-hand side of the screen. One of the files inside the folder will be named routes.rb. Open routes.rb and make it match the example below:

  .draw do
    root 'cars#index'
    resources :cars

Save the file. You can close VSCode now; the rest of the steps take place in the terminal.

Step 3.3: Add Changes to Git

Now that we have made some changes, we need to tell Git. This step is also required to successfully deploy to Heroku.

First, we'll check which files have been updated by running

git status

The output should look similar to the example below:

$ git status
On branch main
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   Gemfile
    modified:   Gemfile.lock
    modified:   config/routes.rb

no changes added to commit (use "git add" and/or "git commit -a")

Great! Now, let's add the changes to staging:

git add .

Then, commit the files in staging:

git commit -m 'updates for heroku deployment'

While we're here, we might as well push our changes to GitHub too:

git push origin main

Step 3.4: Push to Heroku

Now that we've committed the files, we can push to Heroku:

git push heroku main

If you run into an error on the next command stating that you need to use Bundler 2 or greater with this lockfile, you'll need to run:

heroku buildpacks:set

and then run the git push heroku main command again.

This will send the app you created to Heroku. There will be a lot of output in your console. Wait for it to finish.

Step 3.5: Migrate the database on Heroku

Similar to what we did locally before we launched our app, we need to migrate the database on Heroku, which we can do with the Heroku CLI.

Run this command:

heroku run rails db:migrate

You might see some strange output, but as long as you do not have an error, you have successfully deployed a Rails application!

Step 3.6: Visit your new application

It's time to see your app on the web! If you are using Linux or Mac, you can quickly open your app with the command below.

heroku open

Now go and play around with it!

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