Ubuntu fstab mounting

I recently discovered a good way to automount an external hard drive to my server. Automounting basically is the mounting of the drive when the system starts up. Pretty self explanatory. Once it’s mounted it’s good to go until the system is restarted. The issue I was having with my external hard drive as it wasn’t mounting automatically. I was manually mounting it after the system was up. Which really sucks having to do that each time the server is rebooted. The first solution I tried was usbmount. Usbmount seems to be the go to solutuion for most people. For some reason I couldn’t get that to work. It would properly install it but then would not automount the drive at all. Then I ran into a solution that works great called fstab. In order to get it to work I added the following configuration to the /etc/fstab file. Then saved and exited the file.

/dev/sdb1 /media/usb auto utf8 0 0

Now on reboot it’s able to auto mount my external hard drive without any issues.

Git Tags

List

git tag -l

Delete

git tag -d 0.1.0

Delete From Remote

git push origin :refs/tags/0.1.0

Add

git tag -a 0.1.0 -m"0.1.0"

Push Tags To Remote

git push -u origin --tags

All Together

git tag -d 0.1.0 && git push origin :refs/tags/0.1.0 && git tag -a 0.1.0 -m"0.1.0" && git push -u origin --tags

CanCan (CanCanCan)

CanCan was written by Ryan Bates to make role based security simple and fast for Ruby on Rails applications. It was first published in late 2009 and was the go to role based security gem for rails applications. There were several reasons why so many developers wanted to use it. Some of those reasons were because it was fast, easy to setup and worked well. Support for the original CanCan gem ended in mid 2013. Ryan Bates decided to take a break from development all together so the gem was forked by Bryan Rite and is being maintained by him today. This allowed the gem to work with the latest version of rails and is able to keep working when new versions of rails are released. As one of the developers that use’s CanCanCan I can say that it’s just as stable as it’s ever been. It’s a mature gem by this point in time so you won’t see too many breaking changes if any.

Features

One thing that I really love about CanCan is that it gives you an ability class that allows you to define all of your roles and what they can do in one place. You can define as many roles as you want and have them share operations with little effort. Also you are able to assign multiple roles to a user. This will give you the flexibility to only have one role for one purpose. Instead of mixing roles together to fit some custom role you need. You are able to just give the user two roles instead. Another thing that I found really useful is you can pass in a set of criteria that can be applied to the role check. For example a user creates a new record. That record belongs to that user and should only be able to be viewed or edited by that user. With CanCan you can simply pass in a scope like can :edit, ModelName, user_id: user.id. This will apply this scope to the check so only the user who created the record will be able to view or change it. This is really powerful because you can do it all in one place. If you want to setup multiple roles per user simply following this guide (Role-Based-Authorization). Here is how I implemented it based on that how to.


class User < ActiveRecord::Base
  ROLES = %i[role_1 role_2 role_3]

  attr_accessor :roles

  def ability
    @ability ||= Ability.new(self)
  end
  delegate :can?, :cannot?, to: :ability

  def roles=(roles)
    roles = [*roles].map { |r| r.to_sym }
    self.roles_mask = (roles & ROLES).map { |r| 2**ROLES.index(r) }.inject(0, :+)
  end

  def roles
    ROLES.reject do |r|
      ((roles_mask.to_i || 0) & 2**ROLES.index(r)).zero?
    end
  end

  def has_role?(role)
    roles.include?(role)
  end
end

Lessons Learned

One thing I learned while working on my project using CanCan is you need to setup the scopes for the can statements. Originally when I had developed this project I did not add these scopes on. This gave any user the ability to edit any record they had access to. So for example a user was able to view and edit a record that they did not create. This would have caused major issues if it wouldn’t have been caught before going live. Here is an example on how you can provide a scope to your can statement.


can :show, Vehicle, id: user.vehicles.map { |vehicle| vehicle.id }

This will allow a user who’s user_id is in the vehicle table and only that user to view that record. So if a user decided to change the id in the url they will get the access denied error message. You can do this with any active record call as long as it ties back to a user.

Alternatives

When originally choosing CanCan I took the time to look into a couple of alternatives. One of the major players today in rails is Pundit. When Ryan decided to take a leave from the development world a lot of people started looking for an alternative to CanCan. Since it was no longer going to be maintained. A lot of people chose Pundit. I have never used or setup Pundit fully but while doing my research I couldn’t figure out a good way to assign multiple roles to one user. Leave a comment if this is actually simple and I just missed it in the Pundit documentation. I’m sure this is possible but I didn’t want to invest the time digging through the code to find out. CanCan had good documentation in how to do so. At the end of the day I encourage everybody to do their research and determine the solution that best fits their application. I’ve seen CanCan used in multiple applications and so far it’s been able to handle everything thrown at it.

Wallproductions on Rails

Wallproductions is a portal like site that will contain many applications. Currently it contains a couple of applications Gas Tracker and Budget Tracker. Both of these projects are live and are in production use. Over the years it’s gone through a couple of transformations. When it was first created it was a side project. It was something to work on during the weekends to see what was possible outside of what I was doing at work. The reason why the project started was due to a lack of existing applications that did what I wanted. So I set out to create my own.

When it was originally written it was done using PHP. It started out without an off the shel framework. This was a pretty good solution for a while until the project started to get larger. The larger it got the more I thought about it. I was thinking that a framework would be needed. Unless I wanted to spend all my weekends doing tedious things that were already done in the various frameworks. As the only developer working on the project it was important to be able to complete tasks with speed. So instead of creating everything myself I could use some shared code from the framework to handle all of the standard things. Things like ActiveRecord and Routing. So I looked around and I found a couple of frameworks. At the time the Yii framework seemed the most appropriate for my situation. The reason why I choose Yii instead of the other frameworks was simply because I was more familiar with how their ActiveRecord implementation worked. Also it had a pretty good extensions library so I could reuse code shared by others in the community. So I went with that and build the second version of Wallproductions off of it. This worked well and it stayed in the Yii framework for about two years.

During this period of time I change directions in my career and instead of doing PHP development I started doing Ruby development. Specifically working with Ruby on Rails. I did not know much about Ruby or Rails when I started. But after working with it for a short amount of time I was able to be more productive than ever before. Over the course of the next year Wallproductions stayed in the Yii framework. Making additional features and fixing existing bugs. Then the Yii framework introduced their new framework Yii 2. This was a complete rewrite of the framework. So I had a decision to make. Do I want to stay on the first version of Yii for a long time, do I want to rewrite the majority of my PHP code or just move to Ruby on Rails. Seeing that I work on Ruby on Rails on a daily basis it was an option. After carefully considering it I decided that I wanted to go with Ruby on Rails. So I set off on the path of rewriting my entire site using Ruby on Rails.

The first step was to gather all of the old requirements for the system. Then I needed to make sure that I met them. This was not very hard as I was the only developer on this project. Also since I wrote the entire application myself I didn’t need much documentation to understand it. Also I needed to set milestones for myself so I knew I was progressing. I didn’t want to get stuck and then have to go back. But I also didn’t want to keep spinning my wheels if it wasn’t going to work out. As I am sure you realize we all have had side projects that we start and then never finished. I decided early on that if I was going to put a ton of effort into converting Wallproductions I would finish.

The conversion itself actually went faster than I expected. I knew Ruby was very powerful and Rails added even more power to it. What I did not realize is how much power it added. I was able to convert something that I worked up for over three years in under three months. This was not your typical conversion either since it was going cross languages. Also I was not working on this conversion process full time. I was doing so like always on the weekends or nights after regular working hours. Now that I am on Ruby on Rails I am able to complete new tasks at greater speeds. At the end of the day I am glad that it’s on Ruby on Rails. I am a huge fan of the framework and the language. Also the community around it is really good.

Build your Vagrant box using Chef

What is Chef

The goal of Chef is to give you the ability to have an immutable infrastructure. This could be for your stand alone project or for an entire business. The purpose of Chef is to be able to create cookbooks that build your servers automatically. These cookbooks enable you to build your infrastructure in a logical and object oriented way. You don’t have to come from a server administration background to create them either. Chef was built using Ruby scripts. So as long as you have programmed in the past and know a little bit about Ruby you should be all set. For server knowledge all you really have to have is a basic understanding of how servers work. You will also have to have an understanding of what components you need. After that you can browse around for cookbooks and find what you are looking to install. After you build your initial cookbook or download an existing one you will start seeing how simple it can be. I would suggest that you start out with an existing cookbook. You will start finding out that the majority if not all cookbooks you need were already built by the community. Most developers give you full access to their cookbooks Github page. If for some reason you cannot find an existing cookbook you should be able to reference others for how to do it. When I setup my Chef infrastructure all cookbooks were already created. I simply had to modify a couple of them to fit my needs.

Why use Chef

Chef has many use cases. The main one of course is the ability to have an immutable infrastructure. These days with virtualization being so hot it’s important to be able to create a new instance of your infrastructure without having to thinking about. Traditionally before Chef server administrators would write their own shell scripts. After creating these shell script’s they would run them manually after installing the fresh OS. Not only was it time consuming to run these scripts on each server but they also had to be updated all the time. For example if a new version of the application came out. So they tended to get out dated faster. So a tool came out called Puppet. The purpose of Puppet was to take all of these shell scripts and to put them into a tool. This tool would provide some infrastructure so it was easier to manage the scripts. It also allowed you to create generic scripts so when an update came out the process was easier to upgrade. Puppet allows you to define a series of scripts to run. It was definitely a step up from running all of those shell scripts manually. It was a better way to manage these scripts and keep them organized.

After Puppet was out for a while Chef came out. Chef took a lot of the ideas from Puppet and made them better and even easier to use. Chef is the tool that allows a developer to create the infrastructure. It takes infrastructure out of the hands of server administrator’s and into the hands of developers. The reason why Chef is so friendly and powerful is because it was written in Ruby. Ruby is a very elegant language and is very human friendly. Also it’s an object oriented language so it’s very easy to abstract your cookbooks.

Another advantage to Chef is it has great enterprise support. If you sign up for Chef enterprise you can configure which cookbooks run and when. Then you can run a simple knife command and it will interact with the Chef enterprise server. It will look for your cookbooks defined per server and run them in the order you put them in. You can set a different order per server. You can also set it to run different cookbooks per server. Chef enterprise is actually free up to five nodes. If you are at all interested in it it’s a great place to start. So you can create up to five different configurations for free.

How do you use Chef with Vagrant

Vagrant ships with Chef Solo integrated. It’s very easy to get Vagrant started with Chef. The first thing you need to do is get Vagrant installed and setup. You can follow the following instructions on how to do that. After you get that installed you need to setup your Vagrant file with all of your chef configurations.

The following shows some of the configuration needed to get it up and running. The first line is the operating system you want to use. For my case it was ubuntu 14.04 but you can use whatever you like. This even includes Redhat. The next line is even more important. This will tell it to use the latest omnibus version. This line tells Vagrant to install chef on the server before anything else. When you put in :latest in it will take whatever the latest version of Chef available at the given time.

 

  config.vm.box = "chef/ubuntu-14.04"
  config.omnibus.chef_version = :latest

This next set of code is the configuration for Chef to use. These configuration settings are what Chef Enterprise allows you to do through their nice GUI interface. In Vagrant of chef solo you have to define these in the Vagrant file. In turn for Chef Enterprise you define them using their tool.

  config.vm.provision "chef_solo" do |chef|
    chef.cookbooks_path = "cookbooks" # path to your cookbooks
    chef.data_bags_path = "data_bags" # path to your data_bags
    chef_gem_path    = "/opt/chef/embedded/lib/ruby/gems/1.9.1"
    chef.binary_env  = "GEM_PATH=#{chef_gem_path} GEM_HOME=#{chef_gem_path}"
    chef.binary_path = "/opt/chef/bin"

    chef.add_recipe "apt"
    chef.add_recipe "build-essential"
    chef.add_recipe "oh-my-zsh"

    chef.json = {
      oh_my_zsh: {
        users: [
          {
            login: 'vagrant',
            theme: 'af-magic',
            plugins: [
              'git',
              'vi-mode',
              'rails',
              'ruby',
              'bundler',
              'virtualenv',
            ]
          },
        ],
      },
    }
  end

You can also run Chef solo by itself. If you use it standalone without Vagrant you have to tie everything together. I am not familiar with that and cannot speak to how that would work. I hope that this overview helps you learn a little bit more about Chef. I hope that it at least sparks your interest enough to play around with it. Vagrant is a great place to start if you do not have a server to work with.

For a working sample visit my vagrant-chef repo.