Docker ~01 Docker and Raspberry Pi

Today I tried to install Docker on my Raspberry Pi 3 board to check how it will work, just for testing purpose. And you know what? It works very nice. First of all, I install Raspbinan Jessie Lite on SD card. For this point, I log in on a fresh installation and make the system update. After update list of repositories, I made the update of the whole raspberry:

Next step is to install Docker directly from the Docker website for ARM architecture.

This process will take a few minutes. After installation finished we will see the latest installation of Docker and that is running on ARM architecture:

Installation process suggests us to use user pi and add them to docker group. This will allow us to run docker command without using the sudo command.

To check that Docker demons are running we can use: sudo docker info

As you can see docker demons are running. After running classic: sudo docker run hello-world docker can’t find hello version:

The container didn’t start. This problem appears due to incompatible between two architectures: ARM and x86. To solve this problem the best way is to find Docker image that can be run on ARM architecture. So how can we find this image?

The best way is to find an image on Docker Hub. Searching for: ARM or RPI.

Another way is use Docker build to build our own Docker images for Raspberry. To create simple Dockerfile we must create the build directory, and in this folder placed Dockerfile that in my case contains:

To run Docker build: sudo docker build -t /rpi-java8 .
The build will take a while. After finish, we can check by using: sudo docker images. This will list:

To run created Docker image we can use: sudo docker run -it /rpi-java8. But this displayed all options for java because I didn’t specify anything. After adding some variables like: java -version we can see:

What is Docker?

Docker is a tool designed to make it easier to create, deploy, and run applications by using containers. Containers allow developers to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package.

Docker is something like a virtual machine, but Docker allows application use the same Linux kernel without unnecessary dependencies that may be on the host computer.  This allows for some performance and reduces the size of the application.

The huge advantage of Docker is that is open source. That means that anyone can contribute as a volunteer too.

Who is Docker for?

Docker is a tool that’s designed for developers, administrators and software testers. For developers, it means that they can focus on writing code not maintain the environment. Reduce the number of dependencies, and also quick start with setting up initial development. Administrators get flexible and fast way to create and get running environments on easy way.  Software testers get the same environment that developer get to write feature. The last part is very important for two points: there is no misunderstanding in environment dependencies, and if there is a bug in software is easy to track and reproduce as well.

Getting started

On the Internet, there are a lot of information about Docker and why is so sexy thous days. Beginners guides for Docker, command-link simulators, a lot of images that are ready to use.  But I want to create my own tutorial that will be available on youtube channel. Starting with some basics to some advanced setup as well.

Docker and security

As a lot of tools, Docker brings some security too for the applications that are running in this environment, however, containers are not the thing that we can speak about security.  For example, there is something like kernel exploits, DDOS attacks, breakouts, poisoned images and secrets that can be compromised.


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