Custom Subdomains from Models in Rails & Rspec testing too

app-lib-subdomain_constraint.rb

class SubdomainConstraint
  # used in routes to generate subdomains

  # note there is a cache buster in company.rb in case the subdomain is updated - `reload_routes`
  # update it if we write any additional cache entries here
  RESERVED_SUB_DOMAINS = %w[
    www app admin test staging help support wwww cdn owner media intercom mail r _domainkey blog webhooks webhook
    hooks api api-test api-staging referral outbound mail webmail w3 mailboxes io heroku inbound google search 
  ].freeze

  def initialize
    generate_subdomains
  end

  def generate_subdomains
    dynamic_subdomains = Company.where.not(subdomain: nil).pluck(:subdomain)
    @domains = dynamic_subdomains - RESERVED_SUB_DOMAINS

    set_timestamp

    # done to allow codeship to run assets:precompile in prod mode without touching the DB
  rescue ActiveRecord::StatementInvalid
  end

  def set_timestamp
    Rails.cache.write('rails_routes_ts', Digest::MD5.hexdigest(@domains.inspect), expires_in: 1.day)
  rescue StandardError
    warn "WARNING - Error in set_timestamp method, maybe cache host is down? (method:#{__method__} in #{__FILE__}"
  end

  def matches?(request)
    check_if_expired_routes?
    # In development/staging allow multiple subdomains like http://company-614.lvh.me:3000/
    subdomain_to_check = !Rails.env.production? ? request.subdomains.first : request.subdomain
    @domains.include?(subdomain_to_check)
  rescue StandardError
    warn "WARNING - Error detecting Route auth for current domain #{request.host} (method:#{__method__} in #{__FILE__}"
    false
  end

  def check_if_expired_routes?
    generate_subdomains if Rails.cache.fetch('rails_routes_ts') != Digest::MD5.hexdigest(@domains.inspect)
  rescue StandardError
    warn "WARNING - Error in check_if_expired_routes? method, maybe cache host is down? (method:#{__method__} in #{__FILE__}"
  end
end

app-models-company.rb

class Company < ApplicationRecord
  SUBDOMAIN_REGEX = /\A^[a-z\d]+(-[a-z\d]+)*\z/i # I normally put this in application_record.rb or somewhere else but this is easier for a gist
  # associations
  has_many :users

  # validations
  validates :subdomain, length: 3..64, allow_nil: true, uniqueness: true,
                        format: { with: SUBDOMAIN_REGEX, message: 'Valid subdomain characters only' }

  private

  # related to subdomain_constraint.rb
  def reload_routes
    return unless saved_change_to_subdomain?
    Rails.cache.delete('rails_routes_ts')
  end
end

config-routes.rb

Rails.application.routes.draw do
  # keep this above other routes otherwise it will be overridden
  namespace :subdomain, constraints: SubdomainConstraint.new, path: nil do
    # whatever subdomain routes you want served - note the namespace - you can change it of course
  end

  # ... generic routes
end

spec-rails_helper.rb

# Add additional requires below this line. Rails is not loaded until this point!
# ...
require 'support/subdomain_support' # After any SSL - but up top by the rest of your requires
# ...

spec-support-subdomain_support.rb

# Support for Rspec / Capybara subdomain integration testing
# https://gist.github.com/turadg/5399790

def switch_to_subdomain(subdomain)
  # lvh.me always resolves to 127.0.0.1
  hostname = subdomain ? "#{subdomain}.lvh.me" : 'localhost'
  Capybara.app_host = "http://#{hostname}:#{Capybara.server_port}"
end

def switch_to_main_domain
  switch_to_subdomain nil
end

Capybara.configure do |config|
  config.always_include_port = true
end

useage.md

rspec usage is something like:

before(:each) do
  switch_to_subdomain("#{test_company.subdomain}")
end

after(:each) do
  switch_to_main_domain # keeps everything working fine with random test order
end

and then whatever you want to test on the subdomains

accessing in dev

lvh.me and other services redirect to localhost or 127.0.0.1 for testing - work great for testing subdomains. if you aren't working directly on machine (I work on a VM sometimes.) Then just add the subdomains you work with to your hosts file.

subdomain.lvh.me:3000

You should also add whatever loopback service you use to your CI server's host file so any outages don't cause CI problems

notes:

models and attributes aren't magic, use whatever you like.

files are named with dashes in place of slashes just in case you're super fresh. The first time I picked up subdomains from railscast I was two weeks in to rails and not familiar - hopefully that helps someone.