Docker:-Container

Installation Steps on Ubuntu

1 apt update

2 apt install docker.io -y

3 docker --version

4 docker info

5 systemctl status docker

Installation Steps on Centos

1 yum update -y

2 yum install -y yum-utils

3 yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

4 yum install docker-ce docker-ce-cli containerd.io

5 systemctl status docker

6 systemctl start docker

7 systemctl status docker

8 docker --version

9 docker info

10 docker version

docker --version

docker version

docker info

docker

docker hub--->docker engine-->Docker images---> run,stop,deleted

docker pull ubuntu

docker images //list all the images downloaded on your system

docker run -it -d ubuntu //it interactive d demon when images are running it is called containers

sudo docker run -m 4m -dit --name web1 nginx # running the container with a limit of 4mb

sudo docker run -c 614 -dit --name db postgres /postgres.sh

sudo docker run -c 410 -dit --name web nginx /nginx.sh

#Will give 60% to the db container (614 is 60% of 1024) and 40% to the web containe

docker ps // list running images

docker stop <<df86a3b83361>> container id

docker ps -a //list all the continers

docker kill <<container id>> to stop or kill forcefully

docker rm <<container id>> to remove the container

docker exec -it d9a77afafa3b bash

docker run -it --name test ubuntu

create a user using adduser

docker exec -it -u raman test bash

docker rmi 47b19964fb50 //remove the images

Now run the commands in container which is independent of the commands of host OS

exit //to exit from container

Create a Docker Hub account (https://hub.docker.com)

create a user defined images

docker commit <<container id>> <<new image name>> // example we have created test image

docker images

run docker new image and check the changes should be available into that

To remove all the docker containers

docker rm -f $( docker ps -a -q)

install apache2 to the container

apt-get install apache2

service apache2 status

service apache2 start

exit

docker commit 99f528fc4261 ramansharma95/apache

docker run -it -p 82:80 -d ramansharma95/apache

docker exec -it <<container id>>

service apache start

open the web page it shold open the apache2 webpage

push image to docker hub

docker login

docker push ramansharma95/apache

check in the docker hub

---docker save and load command

docker save mywebserver > mywebserver.tar

docker load < mywebserver.tar

-----------Create Local Docker registry

docker container run -d -p 5000:5000 --name local_registry registry

http://<serverip>:5000/v2/_catalog

docker container inspect local_registry

docker image tag ubuntu localhost:5000/ubuntu:latest

docker image push localhost:5000/ubuntu

docker image pull localhost:5000/ubuntu

--------Docker file

FROM :- is define th base image on which we are building eg FROM ubuntu

ADD :- is used to add the files to the container being built, ADD <source> <destination in the container>

ADD . /var/www/html

RUN:- is used to add layers to the base image, by installing components.Each RUN statement add a new layer to the docker image

RUN apt-get update

RUN apt-get -y install apache2

CMD :-is used to run the command on start of the container.These commands run when there is no argument specified while running the container

CMD apachectl -D FOREGROUND

ENTRYPOINT :-is used to strictly run the commands the moment the container intializes. The differnece between CMD and ENTRYPOINT is, ENTRYPOINT runs

irrespective of the fact that whether argument is specified or not

ENTRYPOINT apachectl -D FOREGROUND

ENV :- is used to define the environment in container

ENV name Devops

Create a docker file Dockerfile

FROM ubuntu

ARG DEBIAN_FRONTEND=noninteractive

RUN apt-get update

RUN apt-get -y install apache2

ADD . /var/www/html

ENTRYPOINT apachectl -D FOREGROUND

ENV name DEVOPS

# Base image is CentOS 7

FROM centos:7

# Add a new user "john" with user id 8877

RUN useradd -u 8877 raman

# Change to non-root privilege

USER raman

sudo docker build -t nonrootimage . # create custom image

docker exec -it test2 bash

#Eample of COPY and ADD

FROM centos:7.4.1708

RUN mkdir /mydata

COPY myfiles /mydata/myfiles

ADD myfiles2 /mydata/myfile2

ADD https://xxx/pip-18.1.tar.gz /mydata

ADD pip-18.1.tar.gz /mydata/pipunpack

# CMD and ENTRYPOINT

FROM ubuntu

CMD echo "Hello World"

docker build . -t img1 #Created the image from above Dockerfile

docker run -it img1 # it will return Hello World

docker run -it img1 echo "Hello India" # it will overwrite the CMD and Print Hello India

FROM ubuntu

ENTRYPOINT ["echo","Hello World"]

docker build . -t img1 #Created the image from above Dockerfile

docker run -it img1 # it will return Hello World

docker run -it img1 echo "Hello India" # it will not overwrite the ENTRYPOINT and Print Hello World echo Hello India

FROM ubuntu

ENTRYPOINT ["echo"]

CMD ["Hello World"]

docker build . -t img1 #Created the image from above Dockerfile

docker run -it img1 # it will return Hello World

docker build . -f abc -t img8 # abc is the file name which represents the dockerfile contents

Create an html file in the current directory.(index.html)

Build the docker file

docker build . -t new_dockerfile

check the docker images

run the new docker image docker run -it -p84:80 -d new_dockerfile

docker ps

Docker Storage

-------------------

Data will removed if container is deleted so docker storage is used to keep the data even if container is deleted

Types of Docker

Docker Volume :- is a mountable entity which can be used to store data, in the docker file system

docker volume create my-vol

it is software not the hardware component it can be attached and deattached

docker volume create demo-vol

docker volume ls //to list the volumes

docker run -it --mount source=demo-vol,destination=/app -d ubuntu

docker run -it --mount source=demo-vol,destination=/test --mount source=demo-vol1,destination=/test1 -d ubuntu

remove the container

attach volume to another container

Bind Mounts :- mounts a directory from host machine to the container

To mount the directory which on the host machine to container

docker run -it -v /home/ubuntu/mount:/demo -d ubuntu

Linking docker Containers

run container with name

docker run -it --name container1 -d ubuntu

docker run -it --name container3 --link container1 -d ubuntu

Monolithic Application

is a single-tiered software application in which different components are combined into single program which resides in a single platform.

like a single applicaiton contains Notification,Payments,Customer Service etc

Microservices:- lossely coupled applications

Compose file

sudo curl -L "https://github.com/docker/compose/releases/download/1.23.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

chmod +x /usr/local/bin/docker-compose

docker-compose --version

YAML

it is superset of Json file. There are 2 types of component you need to learn

Map:-key value pair <key>:<value> eg Name:Devops

List:-Sequences of objects

args

-sleep

-"1000"

--------------------------Create a compose file to run db and we app ( file name should be docker-compose.yml)

version: '3.3'

services:

db:

image: ramansharma95/mysql

web:

depends_on:

- db

image: ramansharma95/webapp

To execute compose file

docker-compose up -d

To remove the services for docker compose

docker-compose down

Container Orchestration

Applications are typically made up of indviually containerized components( microservices) that must be orgainsed on networking level in order

of application to run intended.The process of organising multiple containers in this manner is called container Orchestration

Docker Swarm

clustering and scheduling tool for docker containers. With Swarm, IT administrators and developers can establish and manage a cluster of Docker

nodes as single virtual machine.

Creating Docker Swarm Cluster

Docker swarm is installed along with docker

master node

docker swarm init --advertise-addr=13.234.113.221

on slave machine

docker swarm join --token SWMTKN-1-5puumvk4v75hoyohiu6q9x0xoqneybjzeew851iohy0eq5i8v9-1ee7cfdu6udpjqvz8sxtlncpf 13.234.113.221:2377

on master

docker node ls # to view all the joined nodes

Service in Docker Swarm

it is an additional layer with networking part of container

Containers on cluster are deployed using Services on docker swarm. A service is long running docker container that can be deployed to any node worker

docker service create --name nginx --replicas 3 -p 80:80 nginx

docker service ls

check the running containers with docker ps command.

docker service

Docker Network

bridge(default) :- When the application is running in the standalone container that need to communicate

host :- For standalone containers, remove network isolation between container and docker host and use host networking directly (not port forwrading)

overlay:-connect multiple docker demons and enable swarm service to communicate with each other

MacVlan:-allow you to assign a MAC network address to a container to appear as a physical machine.

none:-disable networking

List network

docker network ls

Create the network

1. docker network create -d overlay my-overlay

# docker service create --name website --replicas 3 –-network my-overlay --publish 80:80 hshar/webapp

docker service create --name website --replicas 3 --network my-overlay --publish 84:80 hshar/webapp

docker service ls

create db service

docker service create --name db --replicas 1 --network my-overlay hshar/mysql:5.6

go inside db

mysql -u root -p

intelli

Create database docker;

Use docker;

mysql> create table emp(name varchar(30), phone varchar(30))

-> ;

Query OK, 0 rows affected (0.01 sec)

mysql> select * from emp;

Empty set (0.00 sec)

mysql> select * from emp;

+------+---------+

| name | phone |

+------+---------+

| xyz | 5555555 |

+------+---------+

1 row in set (0.00 sec)

----------------------

Stack and Compose

sudo curl -L "https://github.com/docker/compose/releases/download/1.23.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

chmod +x /usr/local/bin/docker-compose

docker-compose --version

#docker-compose.yml

version: '3.3'

services:

db:

image: mysql:5.7

volumes:

- db_data:/var/lib/mysql

restart: always

environment:

MYSQL_ROOT_PASSWORD: somewordpress

MYSQL_DATABASE: wordpress

MYSQL_USER: wordpress

MYSQL_PASSWORD: wordpress

wordpress:

depends_on:

- db

image: wordpress:latest

ports:

- "8000:80"

restart: always

environment:

WORDPRESS_DB_HOST: db:3306

WORDPRESS_DB_USER: wordpress

WORDPRESS_DB_PASSWORD: wordpress

WORDPRESS_DB_NAME: wordpress

volumes:

db_data: {}

docker-compose up -d

docker container ls

docker-compose scale db=3

docker container ls

docker-compose down

docker container ls

cp docker-compose.yml stack.yml

docker stack --help

docker stack deploy -c stack.yml mystack

docker stack ls

docker stack services mystack

docker service ps mystack_db

docker service ps mystack_wordpress

docker network ls

docker stack ls

docker stack rm mystack

---------------------service update

docker service create --name redis --replicas 5 --update-delay 10s redis:3.0.6

docker service ls

docker service ps redis

docker service update redis --image redis:3.0.7

docker service update redis --image redis:21

docker service ls

docker service rollback redis