Create First Docker Container & App

Please start with first blog on Docker at https://developershome.blog/2023/01/23/what-is-docker/

In this blog, we will understand how to use docker and how to create docker container/image and deploy first application on Docker.

Once Docker is installed, if you go to terminal and write

docker ps -> It will list all the docker container

docker image ls -> it will list all the images

Also, you can also use docker desktop application for the listing containers and images

Now, we will execute below command and start with creating docker image and container

docker run -d -p 80:80 docker/getting-started

First, it checks if local images are available if not it will check on docker hub. And it will download images from docker hub.

What is Docker hub?

Docker hub is Playstore or Appstore for all the docker images. All the open-source projects and all the companies create docker images and upload them on docker hub. We can directly pull that from docker hub. (We can also put our docker image on docker hub)

For example, I want Spark to be installed in my system. I go to docker hub and search for spark and I get list of images from there

In our case, we requested for getting-started image

First image was downloaded from docker hub and then it created container

And container with name crazy_black also created. (if we don’t pass -t and container name, it will give random names)

Now, if we go inside docker container and check what are the components there and what is published on port 80

Command to go inside docker container

docker exec -it docker_cotianer_name/id

We can check that list of all the folders inside docker container
Also, we can see that this is plain vanilla Linux system

Now, if we go to localhost:80 or 127.0.0.1:80, we can see deployed application.

Next Step is deploying application from the scratch

We have web server in Python
And we want to deploy that web server on docker container

Step1

We have basic web server in python using fastapi

On get request we are getting JSON message as below

Step 2

Deploy this application on Docker

Create Dockerfile and specify all the steps which is required

GitHub Link: https://github.com/shahkalpan/Docker

Next step is building image using this docker file

docker build . -t webserver

There are total 5 steps to execute from Dockerfile
First it will download python 3.8 base image from Docker hub
Second it will copy main.py file and create webserver folder in Linux and paste main.py file
Third install fastapi package
Forth install uvicorn package
and last make webserver as a working directory
This way, whatever steps we want to execute, we mention that in Dockerfile and it will always execute while creating image.

Now image is ready

What is image ?

Image is combination of package which created based on Dockerfile. We can export and import this image to anywhere. If you want to relate this with old style windows image file you can relate. We can create image file for any of our application/tool.

From one image, we can create multiple container. and all container work independently. It can be installed on different server or on same server also.