How to access Guest's port 3000 from Host?

Question

Here's my Vagrantfile:

# -*- mode: ruby -*-
# vi: set ft=ruby :

Vagrant.configure(2) do |config|
config.vm.box = "ubuntu-14.04-x64"

# Sync'd folders
config.vm.synced_folder ".",           "/vagrant",  disabled: true
config.vm.synced_folder "~/work",      "/home/vagrant/work", create: true
config.vm.synced_folder "~/apt-archives", "/var/cache/apt/archives/", create: true

# Ubuntu VM
config.vm.define "ubuntu" do |ubuntu|
ubuntu.vm.provision "shell", path: "provision.sh", privileged: false
ubuntu.vm.network "forwarded_port", guest: 3000, host: 8080   # http
ubuntu.vm.network "private_network", ip: "10.20.30.100"
ubuntu.vm.hostname = "ubuntu"

# VirtualBox Specific Stuff
# https://www.virtualbox.org/manual/ch08.html
config.vm.provider "virtualbox" do |vb|

  # Set more RAM
  vb.customize ["modifyvm", :id, "--memory", "2048"]

  # More CPU Cores
  vb.customize ["modifyvm", :id, "--cpus", "2"]

end # End config.vm.provider virtualbox
end # End config.vm.define ubuntu
end

For example, when I run rails app using port 3000, from the guest machine I would accessing http://localhost:3000.

But I'm trying to access the app via host's browser.

None of below worked:

http://10.20.30.100:8080

https://10.20.30.100:8080

http://10.20.30.100:3000

https://10.20.30.100:3000

Browser on the host's showing: ERR_CONNECTION_REFUSED

Answer 1

For security reasons, Rails 4.2 limits remote access while in development mode. This is done by binding the server to 'localhost' rather than '0.0.0.0' ....

To access Rails working on a VM (such as one created by Vagrant), you need to change the default Rails IP binding back to '0.0.0.0'.

See the answers on the following StackOverflow Question, there are a number of different approaches suggested.

The idea is to get Rails running either by forcing the following command:

rails s -b 0.0.0.0

Or by hardcoding the binding into the Rails app (which I found less desirable):

# add this to config/boot.rb
require 'rails/commands/server'
module Rails
  class Server
    def default_options
      super.merge(Host:  '0.0.0.0')
    end
  end
end

Personally, I would have probably gone with the suggestion to use foreman and a Procfile:

# Procfile in Rails application root
web:     bundle exec rails s -b 0.0.0.0

This would allow, I believe, for better easier deployment synchronicity.