Tech-COE-Docker-Basics.txt

Day1
====


1.Why Docker?

2.What is a docker ?
=====================
Docker is a container management service.
The keywords of Docker are develop, ship and run anywhere.
The whole idea of Docker is for developers to easily develop applications, ship them into containers which can then be deployed anywhere.

3.Features of Docker
====================

=>Docker has the ability to reduce the size of development by providing a smaller footprint of the operating system via containers.

=>With containers, it becomes easier for teams across different units, such as development, QA and Operations to work seamlessly across applications.

=>You can deploy Docker containers anywhere, on any physical and virtual machines and even on the cloud.

=>Since Docker containers are pretty lightweight, they are very easily scalable.




Docker Basic Commands
=====================

Basic
: docker version
: docker -v 
: docker --version 
: docker info
: docker --help
: docker login

————————————
Images
: docker images                        To list the images
: docker images -q                     To list the images
: docker pull                          To pull tha image
: docker rmi                           To remove one or more iamges
: docker rmi $(docker images -q)       To remove all images

————————————
Containers
: docker ps                                                 shows only running cotainers(use -a for show all containers))
: docker ps -a                                              shows all containers
: docker rm <container-name>                                remove one or more containers
: docker rm $(docker ps -a -q)                              remove all containers
: docker run <image-name>                                   create a container from image (first time used to container)
: docker run -d <image-name>                                create a container from image in detached mode
: docker run -it <image-name> bash                          create a container from image in interactive mode
: docker start -i <container-name>                          To start the stoped container
: docker stop <container-name>                              To stop running container
: docker logs <container-name>                              To sess logs of contianer
: docker exec -it <container-name> bash                     To interact with container
: docker run --name a-centos -it centos bash                container will not be removed on exit
: docker run --name b-centos --rm -it centos bash           container will be removed on exit
  
————————————
System
: docker stats
: docker system df
: docker system prune (to stop all stoped containers)



Online practice for docker:

https://labs.play-with-docker.com/


====================================================================
7-April-2020

============================
To create a container from image only first time
===================================================
docker run --name a-centos -it centos 

docker start a-centos
docker stop a-centos
docker rm a-centos
docker logs a-centos
docker ps
docker ps -a
docker exec -it a-centos bash
docker rm $(docker ps -a -q)


docker run --name a-centos -it centos bash

docker run --name b-centos -it centos bash

docker network inspect bridge

docker exec -it a-centos bash

# ping 172.17.0.3



docker internall uses networking concepts
==========================================
bridge
host
none



mysql
============
docker run --name p-mysql -e MYSQL_ROOT_PASSWORD=pradeep -d mysql

docker run --name p-mysql -e MYSQL_ROOT_PASSWORD=pradeep -p 3232:3306 -d mysql:5.6


docker logs p-mysql

docker exec -it p-mysql bash

#mysql -uroot -ppradeep

mysql> show databases


======================================
web servers :httpd    default port :80
            :nginx    default port :80
            :mysql    default port :3306
            :mongodb  default port :27017   


docker run --name a-nginx -p  1111:80 -d nginx
docker run --name b-nginx -p  2222:80 -d nginx
docker run --name c-nginx -p  3333:80 -d nginx


docker exec -it a-nginx bash
echo "<h1>Hello A-NgInx Server </h1>" > /usr/share/nginx/html/index.html

docker exec -it b-nginx bash
echo "<h1>Hello B-NgInx Server </h1>" > /usr/share/nginx/html/index.html

docker exec -it c-nginx bash
echo "<h1>Hello C-NgInx Server </h1>" > /usr/share/nginx/html/index.html


8-Apr-2020
===========

To create image from running container
========================================

docker run --name p-apache -d -p 9999:80 httpd

echo  "<h1>Hello Welcome To Custom Apache Image</h1>" >  /usr/local/apache2/htdocs/index.html

docker commit -m 'Index File Content Changed' -a 'Pradeep Chinchole <pradeepch82@gmail.com>' p-apache pradeepch82/apache:1.1

docker login
username :pradeepch82@gmail.com
password :password

docker push pradeepch82/apache:1.1

docker run --name b-apache -p 4545:80 -d pradeepch82/apache:1.1


Dockerfile : 
A text file with instructions to build image
Automation of Docker Image Creation

FROM           :Base Image    
MAINTAINER     :Author Name
ENV            :Environment variable
ADD            :ADD the files while buiding the image
RUN            :To install libraries/packages (executed while building the image)
ENTRYPOINT     :Executed at run time and we can not override the commands
CMD            :Executed at run time and we can override by passing command line argument


Step 1 : Create a file named Dockerfile
Step 2 : Add instructions in Dockerfile
Step 3 : Build dockerfile to create image
Step 4 : Run image to create container

Example  :Dockerfile

FROM ubuntu
MAINTAINER Pradeep Chinchole <pradeepch82@gmail.com>
RUN apt-get update

CMD ["echo", "Hello World..! from my first docker iamge1"]
CMD ["echo", "Hello World..! from my first docker iamge2"]
CMD ["echo", "Hello World..! from my first docker iamge3"]
CMD ["echo", "Hello World..! from my first docker iamge4"]

COMMANDS
: docker build directoryOfDocekrfile
: docker build -t ImageName:Tag directoryOfDocekrfile
: docker run imageid 


Docker File Spring Boot Java Application
================================================
FROM openjdk:8
ADD target/docker-spring-boot.jar docker-spring-boot.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","docker-spring-boot.jar"]


======>

docker build -t pradeepch82/spring-dokcer-demo:1.1 .

docker login

docker push pradeepch82/spring-docker-demo:1.1



Docker file for MYSQL
=======================
# Derived from official mysql image (our base image)
FROM mysql
# Add a database
ENV MYSQL_DATABASE company
ENV MYSQL_ROOT_PASSWORD admin
ENV MYSQL_USER pradeep
ENV MYSQL_PASSWORD pradeep
# Add the content of the sql-scripts/ directory to your image
# All scripts in docker-entrypoint-initdb.d/ are automatically
# executed during container startup
ADD script.sql /docker-entrypoint-initdb.d/


script.sql
===========
use company;
create table employee(id int primary key,name text,salary double);
insert into employee values(101,'RAM',10000.00);
insert into employee values(102,'RAHIM',20000.00);
insert into employee values(103,'DAVID',30000.00);
insert into employee values(104,'PRADEEP',40000.00);





Linking Docker containers with Links
===========================================
Links allow the containers to discover each other and securely transfer the information about one container to another container.


docker network create p-network

docker run --name mysql02 --network p-network -e MYSQL_ROOT_PASSWORD=Password1234 -d mysql:5.6

docker run --name wordpress02 --network p-network --link mysql02 -p 1111:80 -e WORDPRESS_DB_HOST=mysql02:3306 -e WORDPRESS_DB_USER=root -e WORDPRESS_DB_PASSWORD=Password1234 -e WORDPRESS_DB_NAME=wordpress -e WORDPRESS_TABLE_PREFIX=wp_ -d wordpress





Docker Volumes
===============
Docker Volume
===============

1. What are Volumes
2. How to create / list / delete volumes
3. How to attach volume to a container
4. How to share volume among containers
5. What are bind mounts

Volumes are the preferred mechanism for persisting data generated by and used by Docker containers


docker volume  //get information
docker volume create
docker volume ls
docker volume inspect
docker volume rm
docker volume prune



Use of Volumes
===================
Decoupling container from storage
Share volume (storage/data) among different containers
Attach volume to container
On deleting container volume does not delete



Commands
docker run --name MyJenkins1 -v myvol1:/var/jenkins_home -p 8080:8080 -p 50000:50000 jenkins


docker run --name MyJenkins2 -v myvol1:/var/jenkins_home -p 9090:8080 -p 60000:50000 jenkins

docker run --name MyJenkins3 -v /Users/raghav/Desktop/Jenkins_Home:/var/jenkins_home -p 9191:8080 -p 40000:50000 jenkins


References
https://hub.docker.com/_/jenkins/
https://docs.docker.com/storage/volumes/



NOTES

By default all files created inside a container are stored on a writable container layer

The data doesn稚 persist when that container is no longer running

A container痴 writable layer is tightly coupled to the host machine where the container is running. You can稚 easily move the data somewhere else.

Docker has two options for containers to store files in the host machine
so that the files are persisted even after the container stops

VOLUMES  and  BIND MOUNTS

Volumes are stored in a part of the host filesystem which is managed by Docker
Non-Docker processes should not modify this part of the filesystem
Bind mounts may be stored anywhere on the host system
Non-Docker processes on the Docker host or a Docker container can modify them at any time
In Bind Mounts, the file or directory is referenced by its full path on the host machine.


Volumes are the best way to persist data in Docker

volumes are managed by Docker and are isolated from the core functionality of the host machine

A given volume can be mounted into multiple containers simultaneously.

When no running container is using a volume, the volume is still available to Docker and is not removed automatically. You can remove unused volumes using docker volume prune.

When you mount a volume, it may be named or anonymous.

Anonymous volumes are not given an explicit name when they are first mounted into a container

Volumes also support the use of volume drivers, which allow you to store your data on remote hosts or cloud providers, among other possibilities.











4.Components of Docker
======================

=>Docker for Mac - It allows one to run Docker containers on the Mac OS.

=>Docker for Linux - It allows one to run Docker containers on the Linux OS.

=>Docker for Windows - It allows one to run Docker containers on the Windows OS.

=>Docker Engine - It is used for building Docker images and creating Docker containers.

=>Docker Hub - This is the registry which is used to host various Docker images.

=>Docker Compose - This is used to define applications using multiple Docker containers.


5.Installation of Docker on windows?

    Refer this site :

    https://docs.docker.com/toolbox/toolbox_install_windows/


  For windows we need to download Docker toolbox.


To Check Installation
=======================

1.docker version  :shows the version of docker

2.docker info     :gives the indormation of docker

Docker Basic Commands
=====================

Basic
: docker version
: docker --version
: docker -v
: docker info
: docker --help
: docker login
覧覧覧覧覧覧
Images
: docker images
: docker pull
: docker push
: docker rmi
覧覧覧覧覧覧
Containers
: docker ps
: docker run 
: docker start
: docker stop
: docker pause
覧覧覧覧覧覧
System
: docker stats
: docker system df
: docker system prune


To remove all multiple containers
===================================
docker rm -f c2d79dbd5581 39bff36fec4f 5cddf9344a62 152e56f4f4d1 558197ba2d6e e1672924ad4e



Downloading the Latest MongoDB Docker Image
===========================================
   Syntax : docker pull <image-name>  or docker pull <image-name>:<tag>

    Example : docker pull mongo or docker pull mongo:4.0.4


Deploying an Instance of MongoDB as a Container
====================================================
   Syntax : docker run --name <alias-name> <image-name>:tag

   Example : docker run --name mongodb mongo:4.0.4


Interacting with the MongoDB Docker Container with Basic Shell Operations
==========================================================================

  Syntax :docker exec -it <container-name> bash

  Example : docker exec -it mongodb bash

   do some modification
   and commit the changes.  


To commit the changes in container
====================================

 docker commit -m 'Pradeep has created mongodb' -a "Pradep Chinchole<PradeepCh82@gmail.com>" 055e9cfa39fc pradeep-mongodb:latest


To Tag the Image
==================
docker tag pradeep-mongodb:latest pradeepch82/pradeep-mongodb


To Push The Images
====================
docker push pradeepch82/pradeep-mongodb



short cut commands
=====================
docker run --name pradeep-mysql -it mysql:latest bash


docker commit -m "added mysql server" -a "Pradeep Chinchole" pradeep-mysql pradeepch82/pradeep-mysql:latest


docker login

docker push pradeepch82/pradeep-mysql



https://cloud.docker.com/repository/list


1. What are images
2. How to pull image
3. How to run a container using an image
4. Basic Commands

TIPS & TRICKS


What are Images ?
=================

Docker Images are templates used to create Docker containers
Container is a running instance of image

Where are Images Stored
Registries (e.g. docker hub)
Can be stored locally or remote

: docker images --help
: docker pull image
: docker images
: docker images -q
: docker images -f 電angling=false・
: docker images -f 電angling=false・-q

: docker run image
: docker rmi image
: docker rmi -f image

: docker inspect
: docker history imageName



1. What are Containers
2. How to create Containers
3. How to start / stop Containers
4. Basic Commands

TIPS & TRICKS


What are Containers:
Containers are running instances of Docker Images





COMMANDS
: docker ps
: docker run ImageName
: docker start ContainerName/ID
: docker stop ContainerName/ID

: docker pause ContainerName/ID
: docker unpause  ContainerName/ID

: docker top ContainerName/ID
: docker stats ContainerName/ID

: docker attach ContainerName/ID

: docker kill ContainerName/ID
: docker rm ContainerName/ID

: docker history ImageName/ID



What is a Container ?
=====================

A container image is a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run it: code, runtime, system tools, system libraries, settings.

Features of Containers:
======================
=>Are lightweight
=>Fewer resources are used
=>Booting of containers is very fast
=>Can start, stop, kill, remove containers easily and quickly
=>Operating System resources can be shared within Docker
=>Containers run on the same machine sharing the same Operating system Kernel, this makes it faster
=>You can use the command docker container create  to create a container in stopped state



Day2
=====


Docker File
=============

1. What is Dockerfile
2. How to create Dockerfile
3. How to build image from Dockerfile
4. Basic Commands

TIPS & TRICKS

Dockerfile :
A text file with instructions to build image
Automation of Docker Image Creation

FROM
MAINTAINER
RUN
CMD



Step 1 : Create a file named Dockerfile

Step 2 : Add instructions in Dockerfile

Step 3 : Build dockerfile to create image

Step 4 : Run image to create container


Example  :Dockerfile

FROM ubuntu
MAINTAINER Pradeep Chinchole <pradeepch82@gmail.com>
RUN apt-get update
CMD ["echo", "Hello World..! from my first docker iamge"]


COMMANDS
docker build directoryOfDocekrfile
docker build -t ImageName:Tag directoryOfDocekrfile
docker run image



References:

https://www.youtube.com/redirect?event=video_description&v=LQjaJINkQXY&redir_token=E3PErBNVcg9u6KYx6LdmsGYdf4x8MTU2Mjc3ODI4OUAxNTYyNjkxODg5&q=https%3A%2F%2Fgithub.com%2Fwsargent%2Fdocker-cheat-sheet%23dockerfile

https://www.youtube.com/redirect?event=video_description&v=LQjaJINkQXY&redir_token=E3PErBNVcg9u6KYx6LdmsGYdf4x8MTU2Mjc3ODI4OUAxNTYyNjkxODg5&q=https%3A%2F%2Fdocs.docker.com%2Fengine%2Freference%2Fbuilder%2F%23environment-replacement


Docker Compose
==============

1. What | Why - Docker Compose
2. How to install
3. How to create docker compose file
4. How to use docker compose file to create services
5. Basic Commands


TIPS


Docker compose

tool for defining & running multi-container docker applications
use yaml files to configure application services (docker-compose.yml)
can start all services with a single command : docker compose up
can stop all services with a single command : docker compose down
can scale up selected services when required


Step 1 : install docker compose
   (already installed on windows and mac with docker)
   docker-compose -v

   2 Ways

   1.  https://github.com/docker/compose/rel...

   2. Using PIP
    pip install -U docker-compose

Step 2 : Create docker compose file at any location on your system
   docker-compose.yml


version: '3'
services:
  web:
    image: nginx
  database:
    image: redis



Step 3 : Check the validity of file by command
    docker-compose config

Step 4 : Run docker-compose.yml file by command
   docker-compose up -d

Steps 5 : Bring down application by command
   docker-compose down

TIPS
How to scale services

耀cale
docker-compose up -d --scale database=4


Day3
====


day2
=======

docker pull centos

docker run -it centos bash


docker run -it ubuntu bash

//create folders and files

//exit

To Login
==========
docker login

To commit the changes in container
======================================

docker commit -m "Added new folders" -a "Pradeep Chinchole" 2886b219bb66 pradeepch82/pradeep-ubuntu:latest

To push the images
==================

docker push pradeepch82/pradeep-ubuntu:latest




Docker is a software Contairnerization platform

Difference Virtualization vs Contairnerization
==================================================
Virtulization
==============

Host os=> Hypervisor=>(Guest os1,Guest os2....)=>(Bin& Lib, Bin & Lib 2.....)=>(App1,App2,.....)

1.Virtualization is a technique of importing a guest os on the top of host os.
2.This technique is revolution in the beginning because Developers run the different application in different vms all running on same host.
3.This eliminate the need of extra h/w resource and enable the backup allowing the the recovery in failure conditions
4.lowering the total cost of foundation.
 Advantages
 ==========
   1.Multiple OS in the same machine
   2.Easy Maintainance and Recovery
   3.Lower total cost of Ownership

Disadvantages
=============
   1.Multiple VMs Lead to unstable performance
   2.Hypervisors are not as efficient as a host os
   3.Long Boot up process (Approximate 1 minute)
   4.This is using the host system resources
   5.This is very critical in case of real time applications
   where fast processing is required. 
   6.scaling the no of vms is tedious and costly affiar


Contairnerization
==================
Host os=>Container Engine=>(Bin& Lib, Bin & Lib 2.....) =>(App1,App2)

1.Contairnerization is Just Virtualization at OS Level
2.Contairnerization is also a type of Virtualization.
3.It is more efficient as there is no guest os.
4.Binaries and Libraries of the containers are on the host kernel which makes processing and execution very fast
5.Even Booting takes fraction of second. 

 

 Virtualization brings the abstraction at h/w where as Contairnerization brings abstraction to software

   Advantages
   ==========
	1.Containers on same os kernel are lighter and smaller
	2.Better Resource utilization Compared to VMS
	3.Short Boot up process (1/20th of second )



Which of the below option is incorrect ?

1. Contairnerization  is replacing Virtualization 
2. Contairnerization brings process level isolation
3. Hypervisors Manage the VMS.



What is Docker ?
==============
Docker is a Contairnerization  platform which packages your 
application and all its dependencies together in the form of containers
so as to ensure that your application works seamlessly in any environment 
be it Dev/Test/Prod

Host Os=>Docker Engine=> (App1[bin & lib],App2[bin & lib])=>(container1 ,container2)

The no of system scaled up easily.

=============================================================
        VMS                                Dockers
=============================================================

        Elephants           Size           Rabbit

        Tortoise           Speed           Chita

	No integration     Integration     comfortably integrated with Devops tools fo automating the manual process.

              

Resource and Memory Utilization
======================================


Host os 16 GB Ram
==================
         In Case of virtual Macine
         =============================

     Allocation =>  VMs    => Memory Used    =>  Memory Un used
        6 GB    =>  VM 1   =>   4 GB         =>  2 GB
        4 GB    =>  VM 2   =>   1 GB         =>  3 GB
        6 GB    =>  VM 3   =>   2 GB         =>  2 GB
==========================================================
       16 GB                   9 GB              7 GB

7  GB RAM is blocked
7  GB RAM cannot be alloted to new vm.


  

Host os 16 GB Ram
==================
         In Case of Docker
         =============================

     Allocation =>  Docker       => Memory Used    
                =>  Container1   =>   4 GB         
                =>  Container2   =>   1 GB         
                =>  Container3   =>   2 GB         
==========================================================
       16 GB                         9 GB             7 GB


No Ram is allocated for unused
7  GB RAM is unused 
7  GB RAM can be alloted to new containerization.


Building and deployment 
===============================

In case of VMs
             New Builds=>Multiple Guest OS =>Separate Libraries =>Heavy=>More Time

In case of Docker

             New Builds=>Same Host OS =>Separate Libraries =>Light Weight  => Less Time



Integration
=============
In case of Vms Integration is possible but costly due to infrastructur requirement
and not easily scalable.

In case of Docker Integration is Faster,Cheap and scalable.




Q.Which of the follwing option is correct w.r.t creating Docker containers. ?
================================================================================

1.I can build my own image and use it for creating a Docker container. T
 
2.I can pull the image from Docker hub and then run the Docker image. T
 
3.I can create a Docker container without Docker image. F

Docker containers can be created by executing the docker image hence it is not 
possible to run a container without building the image.


Q.Where does the Docker daemon stores the Docker images?

1.Docker Client
2.Docker Host
3.Docker Registry


All the docker images are stored  in the Docker registry which can be either
local repository or a remote Docker hub.












Question
=========
Suppose I have a System with 4 GB RAM and I want to run 4 instances of particular Devops tool 
then which of the below is the best choice?

1. 4 VMS with 4 different instances of that tool
2. 1 VM  with 4 different instances of that tool
3. 4 Docker containers with different instances of that tool