CODEWITHSUNDEEP
dockerdockerfiledevopsdocker-machine
Amal Vijayan
Amal Vijayan

Reputation: 739

Dockerizing a Web Application

I am new to this Containerization and I was wondering how Docker could replace Virtual machines?

I am given a case study in which there are 2 virtual machines each acting as a virtual server, one is a Development server and the other is a Test Server and I am asked to study how Docker could help in managing the workflow efficiently.

In this case the 2 virtual Machines are Servers and the idea of Docker replacing virtual machines is confusing me.

can anyone help me understand this concept.

Thanks in Advance!!

Upvotes: 0

Views: 499

Answers (2)

Karthik Kunjithapatham
Karthik Kunjithapatham

Reputation: 92

I am not sure how a server can be completely replaced by a docker container, so I am assuming you want to replace an 2 applications running in 2 servers into 1 server running 2 containers of each test and dev apps.

I am going to make a few assumptions before I can answer.

  • First I am going to assume, your application is a simple web service that has been deployed on a tomcat/IBM websphere in the server.
  • Secondly, I am assuming the databases are on a different server for both test and dev servers.

Docker Basics

  1. Dockerfile - USing the command docker build, you can create an image
  2. Docker Image - This is created from a dockerfile
  3. Docker Container - When you do a docker run of an image, a container gets created. A running instance of an image is your container

  4. Docker Registry - The place from where you can download base images So here it goes,

  5. Setup docker on a unix server.

  6. Now you need to create 2 containers which will host identical apps. For this, you first need to write a dockerfile, create an image and then start the container using the image.

A sample dockerfile would look like something below

FROM webspher-liberty17:webProfile7

ENV SERVER_NAME=myapptestserver

RUN ["/bin/bash", "-c", "/opt/ibm/wlp/bin/server create $SERVER_NAME"]

EXPOSE 9080 9443


COPY server.xml jvm.options /opt/ibm/wlp/usr/servers/$SERVER_NAME/
COPY *.war /opt/ibm/wlp/usr/servers/$SERVER_NAME/dropins/

CMD ["/opt/ibm/docker/docker-server", "run", "myapptestserver"]

Now when you do a docker build of this docker file, it would create an image with base layer as ibm liberty. Every command after the FROM allows you to add an additional layer, so you can customize to your specifics.

Once you have done the above for both your apps, you practically have two variants of your app running on same server but serving two different environments.

Best part, add this to your CI/CD pipeline in bamboo/jenkins, and you can bring up and down environments in a jiffy.

Upvotes: 2

sanath meti
sanath meti

Reputation: 6519

  • Each docker container is itself act as a virtual machine means each container having its own os isolates the process from host.

    So if you launch 2 containers means you will be running 2 ubuntu(for ex) servers.In each containers you can run your software and expose the service to outside world.

    If eventually docker dies you can relaunch from image without installing OS,application unlike the virtual machines.

    You can transfer the docker images to other server just like the import / export of your application , only requirement is to other server has docker service running.

  • If there are 2 dependent service which is running as container we can link those container for internal communication.Like wordpress as one container and mysql as other where both should have coneected, it that case docker link will help to interconnect.

    You can manage the cpu,memory , disk for docker containers just like virtual machine in any of hypervisors.

    for detailed info : https://docs.docker.com/engine/docker-overview/#docker-engine

Upvotes: 0

Related Questions