Docker

1. What is docker?

A platform for building, running, and shipping applications.

Problem: Code work in your laptop -> didn't work somewhere

Reasons:

• One or more files missing

• Software version mismatch

• Difference configuration settings

With docker you can do it.

• Package Your machine

• Remove machine and code in 1 line code

docker-compose up
docker-compose down

Consistency

2. Virtual Machines vs Containers

Container : An isolated environment for running an application.

Virtual Machines: An abstraction of a machine. You can run many machine like window, linux in mac devices by using a tool called hypervisor.

Hypervisor

• VirtualBox

• VMware

• Hyper-V (window only)

Problems

• Each VM needs a full-blown OS

• Slow to start

• Resource intensive

Containers

• Allow running multiple apps in isolation

• Are lightweight

• Use OS of the host

• Start quickly

• Need less hardware resources

You want to use container to contribute your package to users.

3. Architecture of Docker

• Client - Server Architecture

Kernel is machine of the car.

4. Installing Docker

• Installing docker Hub from https://docs.docker.com

  • Requirements

  • Error W2L installation incomplete -> Download Linux kernel

docker version  -> Client + Server

5. Development Workflow

Application (Docker file) --> Image --> Container

Image

• A cut-down OS

• A runtime environment (eg Node)

• Application files

• Third-party libraries

• Environment variables

Dev -> Registry -> Test

6. Docker in Action

Code:

mkdir hello-docker

cd hello-docker

Edit in VS code

https://app.jsapp.js

Create Dockerfile -> install extension

FROM linux or node // Go to hub.docker.com search node Image
FROM node:aplpine
COPY . /app
WORKDIR /app
CMD node /app/app.js 

docker build -t hello-docker . //Store Image
docker images or docker image ls
docker run hello-docker

Play with docker

• Login docker

• Add new instance

• node -> not found

• docker version

• docker pull codewithmosh/hello-docker

• docker image ls

• docker run hello-docker

7. The linux command line

Because Docker is built on basic Linux concepts

8. Linux distributions

Open source

Distros

• Ubuntu

• Debian

• Alpine

• Fedora

• CentOS

--> Same command

9. Running Linux

hub.docker.com --> search ubuntu -> download image

docker pull ubuntu // docker run ubuntu

docker ps - a

docker run -it ubuntu

Shell prompt :

echo $0 // location of program
echo hello / whoami
history

10. Managing your packages

Package Managers

• npm

• yaml

• pip ...

apt //advance package tools
apt-get

//Install nano
nano // Package
apt install nano
apt list
apt update nano
apt list
apt install nano
nano
apt remove nano


//Install python

11. Linux File system

Tree systems

• /

  • bin

  • root

  • home

  • etc //editable text configuration

12. Navigating the File System

pwd //
ls //list
ls -1
ls -l
cd etc/a
cd etc/apt
cd ../../ //out
ls /bin


cd ~ 

13. Manipulating Files and Directories

cd ~
mkdir test
ls
mv test docker
ls
cd docker/
touch hello.txt
touch file1.txt file2.txt file3.txt
ls
ls -1
mv hello.txt hello-docker.txt
mv hello.txt /etc
rm file1.txt file2.txt file3.txt
rm file*

rm -r docker //remove directories

14. Viewing and Editing file

//Editing
nano // text editor for linux
apt install nano
nano file1.txt


//Viewing
cat file1.txt //viewing file
more file1.txt

//less
apt install less
less 

//head
head -n 5 file1.text

//tail 
tail -n 5 file1.txt

15. Redirection

cat file1.txt > file2.txt