Start Docker,

Have you heard about Docker? It is a kind virtual box but seems pretty lighter than real Virtual box. This article will be outlined what I like to do with docker open source. Especially, I am into embedded docker but get to know basic things of docker before jumping into embedded docker. 

# What Docker is,

If you want to know exact meaning of docker, you can visit to the page(https://www.docker.com/what-docker). Everything you can find what you want to know. But, It's official version. I don't think you don't want to get that kind of knowledge here. I will let you know key factors of docker in my view.

• Containerization Linux based but every OS is fine. 
• Multi functions for solutions not only server, but also embedded.
• Endless evolution and extend their area.

I would like to summarize the main key factors of docker. Of course the site also narrate an explanation like me. I felt when I used and want to express real benefit. In terms of management for a certain service now or in the future you can make it simpler than now. Let's break down in each key statement.

 

## Containerization Linux kernel based but every OS is fine

 

Linux kernel is the representation of open source which mean, we don't pay for that and able to sell it after adapting. The purpose of open source is for contribution to the world. Therefore we don't pay for using docker as well. So, docker is working based on linux and what is containerization?. container which means just a empty box. We can put something into a container and it is possible to run based on kernel. Kernel provides functionalities to work properly in the container side. Yes we know virtual box. What is differentiation between container and virtual box? It is quite different. Virtual box has guest os and separated from host os. Between guest os and host os, hypervisor will be communicated and managed to work. As well as, based on guest os, we need apps and binary to run. Even though host os has the same library, it needs in guest os side too. But container doesn't need to install guest os because it uses kernel functionalities and only it needs library and bin for running apps in container side. This is every one knows the differentiation between virtual box and container. As a container platform, docker is providing mac, windows and other os based. Docker machine is fundamental technology to be a success. Let's visit to the page(https://docs.docker.com/machine/overview/). You can better understand basic knowledge of docker machine. But one thing that I want to mention, docker is not only linux based, also other os based. We can make use cases docker for our solutions.

## Multi functions for solutions not only server, but also embedded.

As far as we know, docker has been focusing to use in server side which means setup environment of development like CI, DevOps and so on. These are the much easier and show it's functionalities. However IoT era which requires to use in embedded side and attracted into it. Tons of IoT devices has been spreading around us and the need will take over the portion of mobile devices. IoT device will make more convenient to live. However how to handle IoT devices. A supervisor will inspect the devices and update when it needs to update. But how? and What?. Docker image will be made by Dockerfile and it will stack up every changing. The image is consisted of a few layers and we can add it on top of the layer when we change or add. Also, embedded devices like to have limited functionalities. Therefore we can make docker image and run into embedded devices like Raspberrypi3.

https://www.raspberrypi.org/blog/docker-comes-to-raspberry-pi/

Basically, we used to control peripheral devices like LED, sensors etc based on RaspberryPI. Once install raspberian or ubuntu into raspberry and use it as like PC. I think it does not different. We can use the same use case. The only thing of differentiation is architecture like arm. If you visit to the site of the below, node app you can install as docker images 

https://blog.alexellis.io/getting-started-with-docker-on-raspberry-pi/

In container of raspberry, node js app will be run and controlled to turn led or not.

## Endless evolution and extend their area.

Every year docker is being held their conference which implies it evolves every day. Docker hub, store, swarmkit, linuxkit moby etc. From tons of developers involved in this projects and have been developing to extend and be stronger than before.

I am not able to expect how much it will be extended in entire world. Definitely, as a open source and container platform, it has various opportunities, I believe. 

Okay, now it's time to see practical skill how to use in embedded side. I will focus on embedded docker how it goes in this category.