Old Guy New Trick

An old guys journey to learn how to code.

Pour Some Subdomains On Me

Author: John on July 20, 2016

SUMMARY:  This post will cover one possible solution for working with subdomains in a rails development environment.  The solution will use lvh.me and comes with an example Rails 5 application, in a very basic form, to assist with demonstrating why one would need to use this type of solution.

Recently I began working on a new Rails application.  The goal of this application is to be a SAAS (Software As A Service) solution.  This solution would be account based where an account will have an owner.  There will also be users, and those users can be associated with more than one account.  

For our solution, we want to host all of the different accounts on one server with the domain name and url of  http://demoapp.dev.  Each account would be a subdomain.  For example, say we have an account named demon-strings.  When our users would log in and access their content, they would navigate to:  http://demon-strings.demoapp.dev.

I have created a basic Rails 5 application that you can clone if you would like to get some hands on experience.  You can find the application here.   Follow the steps provided in the README.md file to setup the demo application on your computer.

Here is a brief summary of those steps (please see README.md for full details):

cd ~/path/to/where/your/projects-go/
git clone git@github.com:hogihung/demo-app.git
cd demo-app
bundle install
rails db:setup
rails db:seed

Let's fire up the rails server the normal way using:  rails s

Next, visit our applications home page by pointing your browser to:  http://localhost:3000.  If all went well you should see the typical basic Bootstrap Jumbotron with a 'Create Account' button.  Feel free to create an account.  If you ran the rails db:seed command from above, two accounts were created for you:

Subdomain      User                   Password
root           sysadmin@demo-app.com  pw
demon-strings  sconner@skynet.com     pw

Next we will try to log in.  Let's try visitng http://localhost.:3000/users/sign_in.  Hmmm, we get an error - "The page you were looking for doesn't exist."

In order to support subdomains, I made an update to the config/routes.rb file:

class SubdomainPresent
  def self.matches?(request)
    request.subdomain.present? && !EXCLUDED_SUBDOMAINS.include?(request.subdomain)

Rails.application.routes.draw do
  constraints(SubdomainPresent) do
    devise_for :users

  root to: "welcome#index"
  resources :accounts

  get '*unmatched_route', to: 'application#raise_not_found'

So, how can we use a subdomain in our development environment?  If we try to use a subdomain with localhost (http://demon-strings.localhost:3000/users/sign_in) we will get an error.  Go ahead and try it, I'll wait.

In the past I have used Pow which you can learn more about here.  But I learned about a new method while at my last job and came across the topic again recently - lvh.me.  Let's try it out.  Visit the url of: http://lvh.me:3000.

Looks just like when we go to localhost:3000.   Now let's try using our subdomain with lvh and visit:  http://demon-strings.lvh.me:3000 and http://demon-strings.lvh.me:3000/users/sign_in.  You should now be able to log in.  Pretty neat, eh?

The keen observer, or tinkerer will notice that at this point it doesn't matter what the subdomin is.  That topic will be saved for another day.


Learn Something New Everyday

Last Edited by: John on July 22, 2016