Docker Intro

Aug 23, 2018

What is Docker?

Docker is a computer program that performs operating-system-level virtualization, also known as “containerization”.
— Wikipedia

After playing with it a couple days ago, some of the important points are:

Docker is one of application that enables “containerization”. Other containerization application: Linux Containers
Docker is primarily developed for Linux environment. It use resource relocation feature in Linux Kernel. Wikipedia
To use docker in Windows, we need to run a Linux VM on Windows.
On windows 7, we will need to use Docker Toolbox
The docker toolbox includes Oracle VirtualBox to run the VM.
On newer windows machine like Windows 10, we do not need Oracle VirtualBox.

From what I’ve observed, Docker Quickstart Terminal will search and turn on the VM on Oracle Virtual Box
If the VM is not exists, it will search for boot2docker.iso inside %userprofile%.docker\machine\cache

Use Kinematic if you want to use GUI to control Docker

To test if the docker configured properly, lets start with a Docker’s Hello World. Execute below command in terminal:

docker run hello-world

In simple terms, when the command executed:

Docker client ask docker daemon to search for docker image with name hello-world in local repository or public repository of docker image.
Docker daemon create a new container from docker image that found
Docker execute command that specified on the docker image, which is to print the message

Everything starts with the Dockerfile. The Dockerfile is the source code of the Image.
Once the Dockerfile is created, we build it to create the image of the container (DockerImage). The image is just the “compiled version” of the “source code” which is the Dockerfile.
Next, we can use the image to run containers. A running container is very similar, in many aspects, to a virtual machine (but it is not a virtual machine).

Good resource to start: