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Category: Virtualization

VirtualBox is a virtualization tool that allows you to run virtual machines within your computer and its available for free.

It is commonly used by developers to create virtual environments along with Vagrant for their development projects.

To install VirtualBox first go to the downloads page here and choose de appropriate downloadable file.

For MS Windows and macOS, just download and run the installer.

Here you can review Oracle's VirtualBox manual.

For Linux distributions:

Ubuntu / Debian:

sudo -s -H
apt-get clean
rm /var/lib/apt/lists/*
rm /var/lib/apt/lists/partial/*
apt-get clean
apt-get update

sudo apt-get install virtualbox-6.1

 Replacevirtualbox-6.1 by virtualbox-6.0 or virtualbox-5.2 to install the latest VirtualBox 6.0 or 5.2 build.

 

Oracle Linux / Red Hat / Centos:

sudo yum -y update
sudo yum install –y patch gcc kernel-headers kernel-devel make perl wget
sudo wget http://download.virtualbox.org/virtualbox/rpm/el/virtualbox.repo -P /etc/yum.repos.d
sudo yum install VirtualBox-6.1

replace VirtualBox-6.1 by the most current version.

 

Once done, make sure the installation was successful:

sudo systemctl status vboxdrv

You will see something like this:

 

Now you are ready to create virtual machines and the most recommended way is to use Vagrant.

 How to install Vagrant in easy steps.

 

 

Details
Category: Virtualization

Vagrant is a great and popular tool for building virtual machines in any computer.

It is widely used for building a virtual machine for development purposes with the exact same environment as in the production server.

This virtual machine can be replicated to as many other computers as you want, ensuring all developers will be working in the same environment, providing great consistency to the project.

Prerequisites: Have installed Oracle VirtualBox.

 

Download Vagrant from here.

You need to choose based on the OS of the host computer. Most popular installations are:

macOS

brew install vagrant

MS Windows x64

https://releases.hashicorp.com/vagrant/2.3.4/vagrant_2.3.4_windows_amd64.msi

Ubuntu / Debian

wget -O- https://apt.releases.hashicorp.com/gpg | gpg --dearmor | sudo tee /usr/share/keyrings/hashicorp-archive-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
sudo apt update && sudo apt install vagrant

 

 

Once installed, open and ssh console (power shell in Windows and verify the installation):

$ vagrant
Usage: vagrant [options] <command> [<args>]

    -v, --version                    Print the version and exit.
    -h, --help                       Print this help.

 ...

 

If you get and error, try log out and login you user.

 

Once done you are ready to install a Virtual Machine.

create a project directory:

mkdir cool_vagrant_project

 cd into it, then execute:

vagrant init

 this will place a Vagrantfile in this directory with basic conf for up and running your virtual machine

If you open with a text editor the Vagrantfile

you will see something like this:

 

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

# All Vagrant configuration is done below. The "2" in Vagrant.configure
# configures the configuration version (we support older styles for
# backwards compatibility). Please don't change it unless you know what
# you're doing.
Vagrant.configure("2") do |config|
  # The most common configuration options are documented and commented below.
  # For a complete reference, please see the online documentation at
  # https://docs.vagrantup.com.

  # Every Vagrant development environment requires a box. You can search for
  # boxes at https://vagrantcloud.com/search.
  config.vm.box = "base"

  # Disable automatic box update checking. If you disable this, then
  # boxes will only be checked for updates when the user runs
  # `vagrant box outdated`. This is not recommended.
  # config.vm.box_check_update = false

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine. In the example below,
  # accessing "localhost:8080" will access port 80 on the guest machine.
  # NOTE: This will enable public access to the opened port
  # config.vm.network "forwarded_port", guest: 80, host: 8080

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine and only allow access
  # via 127.0.0.1 to disable public access
  # config.vm.network "forwarded_port", guest: 80, host: 8080, host_ip: "127.0.0.1"

  # Create a private network, which allows host-only access to the machine
  # using a specific IP.
  # config.vm.network "private_network", ip: "192.168.33.10"

  # Create a public network, which generally matched to bridged network.
  # Bridged networks make the machine appear as another physical device on
  # your network.
  # config.vm.network "public_network"

  # Share an additional folder to the guest VM. The first argument is
  # the path on the host to the actual folder. The second argument is
  # the path on the guest to mount the folder. And the optional third
  # argument is a set of non-required options.
  # config.vm.synced_folder "../data", "/vagrant_data"

  # Provider-specific configuration so you can fine-tune various
  # backing providers for Vagrant. These expose provider-specific options.
  # Example for VirtualBox:
  #
  # config.vm.provider "virtualbox" do |vb|
  #   # Display the VirtualBox GUI when booting the machine
  #   vb.gui = true
  #
  #   # Customize the amount of memory on the VM:
  #   vb.memory = "1024"
  # end
  #
  # View the documentation for the provider you are using for more
  # information on available options.

  # Enable provisioning with a shell script. Additional provisioners such as
  # Ansible, Chef, Docker, Puppet and Salt are also available. Please see the
  # documentation for more information about their specific syntax and use.
  # config.vm.provision "shell", inline: <<-SHELL
  #   apt-get update
  #   apt-get install -y apache2
  # SHELL
end

 

To run a virtual machine you need to execute

vagrant up

 but before doing this you need to change this config file a little bit so you can have the virtual machine provisioned, running in private network and sync'ing a project

You can find online many places where you can download a Vagrant file to get up and running your project in no time.

All of them install an Operating System in the virtual machine, most common are Ubuntu or CentOS and then provision it with all the dependencies required by an specific environment.

For the projects presented in this website you may want to check this post: Vagrant Virtual Machine with CentOS 7, Nginx, MariaDb, NodeJs and PHP 8

Details
Category: Symfony Framework

Composer is a PHP package manager with the purpose of handling all your project dependencies leveraging the great autoloading feature available in PHP.

Modern PHP Projects are developed following Object Oriented Programming Best Practices and one of this is to encapsulate the code into classes, having each class in its own file (...read more on this topics).

These files are organized in folders in such way that  the Symfony project installed here looks like:

 

 

Install composer 2 in Linux / Unix / macOS machines.

Open a SSH console to the machine where you want composer to be installed.

You need to have PHP installed first.

If you want composer 2 to be available in project/directory/path

cd /project/directory/path

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('sha384', 'composer-setup.php') === '55ce33d7678c5a611085589f1f3ddf8b3c52d662cd01d4ba75c0ee0459970c2200a51f492d557530c71c15d8dba01eae') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"

 

If you want composer 2 to be available in any directory in the machine:

sudo mv composer.phar /usr/local/bin/composer

This way you may call composer from everywhere but using sudo. If You don't want to use sudo, you may want to install composer 2 only for your user:

mv composer.phar ~/.local/bin/composer

 

 

Install composer 2 in Microsoft's Windows machines.

Just download the executable from here

Then run the .exe file. This .exe file will set the PATH for you so you can call composer 2 from everywhere in this machine.

 

Details
Category: Symfony Framework

In the Symfony Framework, a listener is a class that listens to a specific event and executes a specific code when that event occurs. Listeners are used extensively in Symfony to implement various functionalities in a decoupled and reusable way.

Listeners are part of Symfony's event-driven architecture, where events are dispatched and listeners are registered to handle those events. When an event is dispatched, all registered listeners for that event are called in the order of their priority (which can be set when registering the listener), and each listener can execute its own code to respond to the event.

Listeners can be implemented in different ways in Symfony, depending on the context and the use case. Some examples of listeners in Symfony include:

- Kernel event listeners: These listeners are used to handle events related to the Symfony kernel, such as the request, response, exception, and termination events. Kernel event listeners can be used to modify the behavior of the Symfony kernel, add custom functionality to the application, or handle errors and exceptions in a centralized way.


- Doctrine event listeners: These listeners are used to handle events related to Doctrine, such as the prePersist, postPersist, preUpdate, postUpdate, preRemove, and postRemove events. Doctrine event listeners can be used to execute custom code before or after a specific Doctrine operation, validate or transform data, or implement custom business logic.


- Form event listeners: These listeners are used to handle events related to Symfony forms, such as the preSubmit, postSubmit, preSetData, and postSetData events. Form event listeners can be used to modify the form data, validate the form input, or execute custom code before or after the form submission.


Overall, listeners are a powerful and flexible mechanism in Symfony that enable developers to implement complex functionalities in a modular and extensible way.

Further reading:

Sample Listener implementation in Symfony 5+

Symfony Events and Listeners.