Docker y Docker compose

When you hear people talking about Docker and / or Docker Compose, it sounds exciting but it sounds a bit like Chinese because everything is too technical.
The learning curve is not exactly smooth, although thanks to Youtubers like "Pelado Nerd" you can save yourself a lot of headaches.

I love Docker, and the more I know about this type of virtualization so close to the operating system (which has nothing to do with virtualizing machines with VirtualBox and the like), the more I virtualize things.

You can virtualize development environments, cms’s, online stores.
With Docker you can even virtualize applications (at least on Linux), you can find on the web wide world for example, how to virtualize with docker compose the famous sublime text.

¿And what is Docker?

 

Docker is a software virtualizer.
To catch it fast.
It is as if you installed a virtualbox, but without installing the operating system, only the software in question. And it doesn't matter if you use Ubuntu or Windows, they will all work exactly the same in isolation from your environment.
Docker installs images and containers, always using your operating system.

In Docker an image is software, mysql, wordpress, drupal.
In Docker a container is the instance of an image.

I explain the latter better to you.
You can install 3 different wordpress, each of those wordpress is going to be the site or domain that you will upload to your hosting, and that you will probably first prefer to create it and test it locally.

Docker Containers and Images

When you do a "docker build" or "docker up", the first thing Docker will do is create the images, and then the containers.

If your docker-compose file contains the "ingredients" for Apache, Nginx, WordPress, and Phpmyadmin, this will automatically create each of those images.

Then you will create a container for each of those images.
The container is an instance of the image. As if the image were a template and the container an extension of it.
And if we clone this environment, or create another that also uses Apache, it will use that same image.
That is to say. If we have 5 sites virtualized with Docker that use Apache, it will not install 5 apaches, but it will not install only 1 and it will be shared for all containers.

More about Docker

The magic of docker is such, that you can run php 5 environments, while your machine remains at version 7.2, or it just doesn't have php.

The way everything works in docker is by forming a network between the containers, where they are seen and understood through the ports.

For example, you install a mysql specifying as port 8090.
You install 3 different cms’s, which will need mysql. Well, you tell these that their mysql is on port 8090. And now ...

You install a software with a php 4, uuuuuuuuuuuuuuuuu, for port 9091.
In the browser you will use localhost: 9091 and it will appear that the software is on your own machine.
You can also go into the container, and work inside and run things in it, which would be the analog of being in the console of a virtualbox.

And what is docker compose?

Well, if Docker is magic, docker compose has no words.
Docker compose is a little file, where you describe the list of images and containers that you want to create, and how they interconnect between them.

It is like a cooking recipe, where you are going to declare what ingredients you use and how you mix them.

This is done with the command docker-compose.yml
And when you go to the folder of that file, you do "docker-compose up".
Then the thermo-mix acts 😀

Example of a wordpress docker-compose:

services: 
  php: 
    image: wordpress 
    restart: 'always' 
    ports: 
      - 0.0.0.0:80:80 
    depends_on: 
      - mysql 
    links:  
      - mysql 
    volumes:  
      - ./data/www:/var/www/html 
 
  mysql: 
    image: mysql 
    restart: 'always' 
    volumes:  
      - ./data/mysql:/var/lib/mysql 
    environment: 
      MYSQL_ROOT_PASSWORD: root 
      MYSQL_DATABASE: my_site 
      MYSQL_USER: root 
      MYSQL_PASSWORD: root

Where "volumes" is the volatile data.
Look at mysql, volumes. We are making mysql data to be in a shared folder with the host. ("Host" is our real machine, "container" is inside docker)

That is, when we zip the folder where the docker-compose.yml file is located, and we take it to another place, the new container will "hook" the mysql data again.

Enlaces útiles de docker y docker compose

Useful docker and docker compose links
By the way, official Docker site and its documentation
https://docs.docker.com/

If you want to install it, you will find by google how to do it from your operating system.
For example to install it from ubuntu 18 https://www.digitalocean.com/community/tutorials/como-instalar-docker-compose-en-ubuntu-18-04-es

Advantages of dockerizing an environment.

• You can "turn on" or "turn off" those cms's and robots with a single command in the console "docker-compose up" and "docker-compose down" (and with it the resources occupied by all those components that you will not need if you turn on the pc to listen to music)
• You can decide which data is volatile (mysql, plugins, images) and place it in a folder on the host
• When you take copies and clone a Docker-compose folder and its volatile data, recreating the container elsewhere you won't need to configure anything (that's one of the great things about Docker)
• Before doing a risk operation, as I mentioned in the previous point, you copy the entire folder, and bualá. You do not go through the arduous task of having to export and import the databases (if you set it right, of course)
• You can take the wordpress from the server, download it to your local, and everything is mounted with a "docker-compose up". You will only need to change the url configuration, and you will have an identical copy on your premises in a few minutes and with almost no effort.
• When a client tells me that something does not work well in their prestashop, and it is difficult for me to analyze it on their server, there will be a huge difference between whether their environment is in a Docker or not.
• Yes it is, bingo! I just have to download it, start it on my premises, and analyze and debug everything locally.
• You will be able to have your Desktop PC, with your personal things, your games, multimedia tools, without installing in it the work environments that you do not like to have on your real machine, which on many occasions can create problems for you.
• I personally don't like having an apache or an nginx in my real environment, and having to update or maintain it. Or that when it breaks it forces you to break your head or reinstall the entire operating system because of this.
• Or vice versa, that your system breaks, and when you reinstall it you have to start from scratch, and reinstall apache, mysql, postgres, import all the databases.
• If I have it in docker, I just have to install Docker, do "docker-compose up" on each site, and it's like the difference between making a coffee and having to paint the house again.

If you have never tried docker-compose, when you do it will be like eating pipes, you will not want to stop learning and using it more and more.