This document discusses Docker containers and how they compare to virtual machines. It explains that Docker containers are lightweight software packages that bundle code and dependencies and allow applications to run in isolation on a shared operating system kernel. Containers take up less space than virtual machines and start almost instantly. The document provides examples of Dockerfiles used to build container images and Docker commands to build, run, and execute commands inside containers.

1. Docker Container
Presented by Naveen Kumar Auvusali 02-06-2018

3. Virtual Machines Explained
• A virtual computer system is known as a “virtual machine” (VM): a
tightly isolated software container with an operating system and
application inside.
• Each self-contained VM is completely independent. Putting multiple
VMs on a single computer enables several operating systems and
applications to run on just one physical server, or “host.”
• A thin layer of software called a “hypervisor” decouples the virtual
machines from the host and dynamically allocates computing
resources to each virtual machine as needed.

4. Docker

6. Size
• The following image explains how Virtual Machine and Docker Container utilizes the resources
allocated to them.
Size

7. Start-Up

8. Integration

9. What is
Docker?
• Docker is a tool that allows developers, sys-admins
etc. to easily deploy their applications in a sandbox
(called containers) to run on the host operating
system i.e. Linux. The key benefit of Docker is that it
allows users to package an application with all of its
dependencies into a standardized unit for software
development
• Docker containers are lightweight alternatives to
virtual machines and it uses the host OS.
• You don’t have to pre-allocate any RAM in
containers.

11. CONTAINERS ?

12. Containers
Containers are an abstraction at the app layer
that packages code and dependencies together.
Multiple containers can run on the same machine
and share the OS kernel with other containers,
each running as isolated processes in user space.
Containers take up less space than VMs
(container images are typically tens of MBs in
size), and start almost instantly.

13. Containers

16. Sample Docker file
• FROM node:9.11.1-alpine // Base image alpine
• WORKDIR /app
• ADD . /app
• CMD["node","server.js"] // Entry point

17. server.js
• var http = require('http');
• http.createServer(function (req, res) {
• res.writeHead(200, {'Content-Type': 'text/plain'});
• res.end('Hello Pervacians !');
• }).listen(8080);

18. Commands
• #build image
• docker build -t testbuild .
• #run image
• docker run -it -p 8182:8080 testbuild
• #run command in container
• docker exec -it <container id > command

19. References
• https://github.com/docker/labs/tree/master/beginner/
• https://examples.javacodegeeks.com/devops/docker/docker-hello-
world-example/
• https://rominirani.com/docker-tutorial-series-writing-a-dockerfile-
ce5746617cd