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Docker – From Scratch To App (DevOps) – Part-1

Introduction

• Docker is a platform where we can develop our application as a separate environment.
• We can run, deploy and manage our application inside a docker.
• We can create our application irrespective of the infrastructure of our system so that is a big advantage of using docker.
• Having our application independent of the infrastructure helps in the faster development of the software.
• Docker helps in faster delivery as no time is wasted around managing the correct versions of the packages.
• Testing is also done in docker.
• Overall we can conclude that docker act as a separate machine common to everyone that increases productivity and helps more in focusing on the code.
• Docker is written in Go Programming Language (the backend of Docker).

Installation

• We can directly install docker or docker desktop both work fine.
• Installation – https://docs.docker.com/get-docker/

Hello World! in Docker

• Let’s get our hands dirty with docker.
• After installation, let’s check whether it is installed correctly or not.
• So for that let’s run the following command on our terminal.

docker --version

• Currently, I am using 20.10.7, so we can see that docker is installed successfully for me.
• This is how the UI of the Docker desktop looks like.

• Now we have everything set up, so let’s first understand certain things about docker.
• Container – A container is a lightweight isolated environment where we can package and run our application.
• Many Container can be run simultaneously.
• Most of the times applications are deployed as a container.
• Image – Docker Images are the read-only instructions that are used for creating a container.
• One Image can inherit another image, likewise, multilevel hierarchy is supported.
• Hello-World image is already present in docker, so to access it, let’s run the below code.

docker run hello-world

• Here we can see that the image was not present on our local system, so it downloaded/pulled the image for us and has shown the Hello from Docker !, message.
• We are now done with the Hello World! , let’s move to some more stuff.

Common Commands used in Docker

• To see the images on your local system –

docker images

• In the output, we can see all the images are present in our local system.
• Docker images command work same as –

docker image -ls

• Both of them present the same output.
• Whenever we run an image we are creating a container, so the docker run command creates a container.
• We can run the images/containers with a different name also, for that –

docker run --name DemoName hello-world

• Here we can see that the container ran successfully.
• To see all the images that you have run-

docker ps -a

• Here we can the name of the image, container id container name as well as status and their creation time with ports.
• Similarly to see the last ran container, we can use-

docker ps -a -l

• To delete a docker image-

docker rmi -f imageName

• Here we can see in the output that we have successfully deleted hello-world image.
• We can use docker rm to delete a stopped container.
• To see all the currently running containers–

docker container ls

• To stop a container we can use-

docker stop containerId

• To forcefully stop a container we can use docker kill instead of docker stop.

docker kill containerId

• To login into someone’s organization hub or docker page–

docker login

Conclusion –

• That’s it from the first part.
• In the next part, we will learn how to create an image and what are the different tags that are used with an image.

References-

• https://docs.docker.com/

Still Curious? Visit my website to know more!

For more interesting Blogs Visit- Utkarsh Shukla Author

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