=======
Docker
=======

=> Containerization software

=> Using Docker we can run our application in any machine.

=> Docker will make our application portable.

====================
Life without Docker
====================

=> We need to install softwares in computer to run our application

Ex: Ng 18v, Java 17v, MySQL 8.5v

=> To handle load, we will deploy our application in multiple machines.

=> If We want to deploy our application in 100 machines then we need to install required softwares in all 100 machines.

Note: In future if we want upgrade our project from Java 17 to Java 21 then we need to un-install java 17 and install java 21 in 100 machines. IT is not easy task.

=> To overcome this problem we will use Docker.

=================
Life with Docker
=================

=> If we use Docker it will take care of softwares installation required to run our application.

=> We will execute our application as a Docker container.

	Container = Virtual Machine (linux vm)
	
=> Docker works based on Virtualization concept.

===========================
What is Containerization ?
============================

The process of packaging our "application code + application dependencies (softwares)" as single unit for execution is called as Containerization.

======================
Docker Architecture ?
======================

Dockerfile : It contains instructions to build image

Docker Image : package of code + dependencies

Docker Registry : Used to store docker images

Docker Container : Virtual machine in which application will be deployed.

=======================
Docker Setup in Linux
=======================

https://github.com/ashokitschool/DevOps-Documents/blob/main/02-Docker-Setup.md

================
Docker Commands
================

docker images : display docker images available in our machine.

docker pull : download docker image 

	docker pull <image-name>
	
docker run : run docker image (create container)

	docker run <image-name / image-id>

docker ps : display running docker containers

	docker ps 
	
	# display stopped containers
	docker ps -a 
	
docker stop : Stop docker container 

	docker stop <container-id>
	
docker start : Start docker container 

	docker start <container-id>

docker rm : To remove stopped docker container 

	docker rm <contianer-id>

docker rmi : Remove docker image 

	docker rmi <image-name / image-id>
	

Note: To remove all stopped containers and un-used docker images we can use below command 

		docker system prune -a


=======================================================
Running Real-world applications using docker images
=======================================================

docker pull ashokit/spring-boot-rest-api

docker run ashokit/spring-boot-rest-api

docker run -d ashokit/spring-boot-rest-api

docker ps

docker logs <container-id>

docker run -d -p host-port:container-port ashokit/spring-boot-rest-api

	Ex: docker run -d -p 9090:9090 ashokit/spring-boot-rest-api		

########### Java App URL : http://public-ip:host-port/welcome/{name}	

docker pull ashokit/python-flask-app
docker run -d ashokit/python-flask-app
docker run -d -p 5000:5000 ashokit/python-flask-app

########### Python App URL : http://public-ip:host-port/

Note: Here -d represents detached mode.
Note: Here -p represents port mapping. (host-port:container-port)


Note: host port and container port no need to be same.


Note: Host port number we need to enable in ec2-vm security group inbound rules to allow the traffic.


=============
Dockerfile
=============

=> Dockerfile contains set of instructions to build docker image.

		filename : Dockerfile

=> Dockerfile contains set of instructions to build docker image.

=> To write dockerfile we will use below keywords


1) FROM
2) MAINTAINER
3) RUN
4) CMD
5) COPY
6) ADD
7) WORKDIR
8) EXPOSE
9) ENTRYPOINT

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FROM
=======

=> It is used to specify base image (dependent software) for our application

Ex :

FROM tomcat:9.0

FROM openjdk:17

FROM python:3.3

FROM node:19

FROM mysql:8.5


============
MAINTAINER
============

=> To specify author of Dockerfile (who created/modifed Dockerfile)

Ex:

MAINTAINER Ashok <ashok.b@oracle.com>

Note: It is optional.

========
RUN
========

=> RUN keyword is used to specify instructions (commands) which are required to execute at the time of docker image creation.

Ex :

RUN 'git clone <repo-url>'

RUN 'mvn clean package'

Note: We can specify multiple RUN instructions in Dockerfile and all those will execute in sequential manner.

====
CMD
====

=> CMD keyword is used to specify instructions (commands) which are required to execute at the time of docker container creation.

Note: Using CMD we can run application in container

Ex : 

CMD "java -jar sbapp.jar"

CMD "python app.py"

Note: If we write multiple CMD instructions in dockerfile, docker will execute only last CMD instruction.


===========
ENTRYPOINT
===========

> It is used to execute instruction when container is getting created.

Note: ENTRYPOINT is used as alternate for 'CMD' instructions.

Ex-1 :  CMD "java -jar app.jar"

Ex-2 :  ENTRYPOINT ["java", "-jar", "app.jar"]

=====
COPY
=====

=> COPY instruction is used to copy the files from source to destination.

Note: It is used to copy application code from host machine to container machine.

		Source : HOST Machine

		Destination : Container machine

Ex : 

COPY target/app.jar  /usr/app/

=====
ADD
=====

=> ADD instruction is used to copy files from source to destination.

COPY target/app.jar  /usr/app/

ADD <http-url>  /usr/app/

=========
WORKDIR
=========

=> WORKDIR instruction is used to set / change working directory in container machine.

Ex : 

COPY target/app.jar   /usr/app/

WORKDIR /usr/app/

CMD "java -jar app.jar"

=======
EXPOSE
=======

=> EXPOSE instruction is used to specify application is running on which PORT number.

Ex :

EXPOSE 9090

Note: It is optional.


=========================================
How to push docker image into docker hub 
=========================================

# login into docker hub account 
docker login

# push docker image
docker push <image-name>


===================================
Dockerizing SpringBoot application
===================================

=> Spring Boot is a java framework which is used to develop java based applications.

=> Spring Boot applications will be packaged as a jar file. We need java software to run spring boot application as jar file.

=> To run the jar file we will use below command

	Ex:  java -jar <jar-file-name>

Note: When we run springboot application jar file, internally springboot will use tomcat server as "embedded container" with default port number 8080.


# App Git Repo : https://github.com/ashokitschool/spring-boot-docker-app.git


================ Java SpringBoot App Dockerfile ===========

FROM openjdk:17

COPY target/sb-app.jar  /usr/app/

WORKDIR /usr/app/

EXPOSE 8080

ENTRYPOINT ["java", "-jar", "sb-app.jar"]

============================================================


1) Clone git repo in docker host machine (linux)

git clone https://github.com/ashokitschool/spring-boot-docker-app.git

2) Go inside project directory and perform maven build

cd spring-boot-docker-app
mvn clean package

3) Create docker image

docker build -t ashokit/sb-app .

docker images

4) Create docker container

docker run -d -p 8080:8080 --name ashokit ashokit/sb-app

docker ps

docker logs <container-id>

5) Access application URL in browser

	Linux : http://public-ip:8080/

====================================================
Dockerizing Java Web application (no springboot)
====================================================

## App Git Repo : https://github.com/ashokitschool/maven-web-app.git


=> Normal java web apps will be packaged as war file.

Note: war file will be created inside project target directory.

=> To execute that java web application we need to deploy that war file in tomcat server.

=> Inside tomcat server we will have "webapps" folder. It is called as deployment folder. 

=> To run war file we need to keep war file inside tomcat/webapps folder.

================ Dockerfile for Java web application ===============

FROM tomcat:latest

EXPOSE 8080

COPY target/maven-web-app.war /usr/local/tomcat/webapps/

====================================================================

=================================
Dockerizing Angular application
=================================

=> Angular is a frontend framework

=> Angular is used to develop frontend of the applications

Note: Angular developed by google company.

=> We will use Node Package Manager( NPM ) to build angular applications

Note: When we build angular app it will generate "dist" folder for deployment

=> To run angular app we can copy "dist" folder data to "Nginx" server.

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

FROM node:18 AS build

WORKDIR /app

COPY package*.json ./

RUN npm install

COPY . .

RUN npm run build --prod

FROM nginx:alpine

COPY --from=build /app/dist/angular_docker_app /usr/share/nginx/html

EXPOSE 80

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

git clone https://github.com/ashokitschool/angular_docker_app.git

cd angular_docker_app

docker build -t ngapp .

docker images

docker run -d -p 80:80 ngapp

Note:  Enable 80 port number in security group inbound rules.

=> Access application in browser using docker-server public ip address

		URL : http://public-ip/

============================================================================

Docker Compose Tutorial : https://youtu.be/7FBsiR7-e3Q?si=rcbHZ7dKIpZPajk2

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