docker.org

Make

Docker

I hardly know her!

or:

wtf is a container??

What is it?

a program that performs operating-system level virtualization

Like a virtual machine, BUT…

All containers are run by a single operating system kernel

As opposed to one kernel for every traditional VM

This makes the docker ecosystem more lightweight

Images vs. Containers

An Image is like a template for a Container

An image might be a linux distro, or a webserver, or a database, or some sort of development environement, or even…

docker itself

About Images

Images are defined in a Dockerfile, which specifies a base image to build off of, commands to run to set things up, etc.

About Containers

Containers are the actual VM-like processes that you run on a computer

They are based on images, and you start them with

`docker run …`

Let’s try an example

Suicide Linux!

`docker run –rm -it tiagoad/suicide-linux` [https://hub.docker.com/r/tiagoad/suicide-linux/]

Let’s break that down

• docker - A runtime for containers
• run - Run a command in a new container
• –rm - Automatically remove the container when it exits
• -it - interactive tty, as in you can access the shell
• tiagoad/suicide-linux - a docker image from hub.docker.com

Here’s a teensy-bit more practical example?

NGINX - a webserver

$ docker run –rm -v ~/org/:/usr/share/nginx/html:ro -p 3000:80 -d nginx

• -v allows sharing directories from the host to the container (in this case my ~/org/ gets mounted at /usr/share/nginx/html)
• -p allow mapping a host port to a container port (so the container’s port 80 gets sent to my port 3000)

Now you can go to <my-ip>:3000/docker.html and see this page