Docker is an open source platform that is free and easy to use. It is used to create, implement, and manage containerized applications. Containers simplify distributed programming, making them popular as companies shift to cloud-based development and multi-cloud hybrid setups. It helps developers to bundle programs into containers that can be run and executed in any given environment. Docker is also a toolkit that enables automation by allowing developers to use just one API to create, deploy, operate, change, and pause containers using easy commands. Development of containers can also be done without Docker, but using Docker makes the containerization process simpler, faster, and reliable.
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Why is Docker important?
With rapid changes in business, the need for a tool that can meet business requirements at that pace has also increased. Docker containers help to deploy softwares into production easily with limited human interaction. It enhances developer productivity dramatically by ensuring that if code works great in a test environment, it will almost certainly function in production. Docker also has self-healing capabilities. If a container is not responding, it restarts it or creates a new one, making troubleshooting easier and faster. Thus we can say that the advantages of Docker are two-fold: reduction in Capital Expenditure and in Operational Expenditure. In a traditional deployment, applications were deployed on physical servers and maintenance wasn’t easy, only 20-30% of resources were utilized. But in container deployment using Docker, an application is deployed through lightweight images, reducing the need of full-blown Virtual Machines to run applications, increasing the utilization to 70-80%. Docker increases time-to-market by 300%, developer productivity by 100%, deployment velocity by 60%, issue resolution rate by 70%, and IT operational efficiency by 50%.
Docker Lifecycle Commands
The container lifecycle is a series of stages, starting from the creation of the container, running of the container, updation of the container to its destruction. 1) docker - This command is used to display all docker commands
2) docker version - This command helps to find which docker version you are currently working on. It will display the current docker version and the build name.
Syntax: docker version
3) docker info - This command will display the information about the systems.
Syntax: docker info
4) docker pull - In a docker container lifecycle, the first thing we do is pull the images. This command helps in pulling images from the repository of Docker Hub
Syntax: docker pull
Example: docker pull centos
5) docker build - This command is used to build an image from a Dockerfile as well as a "context". The context of a build is the set of files in the supplied URL or path. Any of the files in the context can be referenced by the build process.
Syntax: docker build
Example: docker build -t apache_centos ( -t allots a tty and connects to stdin and stdout. Centos is the name of the docker image that created the container)
6) docker run - This command helps in running a container from a docker image. It adds a writeable layer to the picture specified in the command.
Syntax: docker run
Example: docker run e98b6ec72f51
7) docker commit - This command is used to create a new image from an already existing container file by committing container changes.
Syntax: docker commit
Example: docker commit e98b6ec72f51 ubuntu-centos
8) docker ps - If you want to see the list of all the operating containers, this is the command you should use. You can use the -a flag to view the containers including the stopped and paused ones.
Syntax: docker ps
9) docker start - This command will start one or more paused/stopped docker containers
Syntax: docker start
Example: docker start 6bfb1271fcdd
10) docker stop - This command will stop one or more running docker containers.
Syntax: docker stop
Example: docker stop 6bfb1271fcdd
11) docker logs - Use this command to see logs of a container. Viewing logs help in debugging issues.
Syntax: docker logs
Example: docker logs 6bfb1271fcff
12) docker rename - This command will rename docker containers.
These commands execute docker containers containing images. We have listed some common Docker Image commands below: 1. docker build - This command is used to build an image from a Dockerfile
Syntax: docker build
Example: docker build -t apache_centos (Here -t allots a tty and connects to stdin and stdout. Centos is the name of the docker image that created the container)
2. docker pull - This command pulls docker images from docker hub repository.
Syntax: docker pull
Example: docker pull ubuntu
3. docker tag - This command will add a new tag to a docker image.
Syntax: docker tag image/TAG
Example: docker tag reactjsdocker fosstechnix/reactjsdocker:v2.0
4. docker images - This command is used to display all the images installed on the system
Syntax: docker images
5. docker push - This command is the opposite of docker pull. It pushes docker images to the docker hub repository.
Syntax: docker push Name
Example: docker tag reactjs docker_registry.com/reactjs:v2.0
6. docker history - If you wish to view the docker image’s history, this is the command you should type in.
Syntax: docker image history IMAGE
Example: docker history --no-trunc
7. docker inspect: This command is used to get low-level information on any of the Docker objects. This tool displays extensive information about the Docker-controlled constructs.
11) docker rm - This command will remove a docker container. But to remove a container, you need to stop it and then remove it.
Syntax: docker rm
12) docker inspect - This command is used to get low-level information on any of the Docker objects. This tool displays extensive information about the Docker-controlled constructs.
Syntax: docker inspect
Example: docker inspect cbfa678479b6
13) docker attach - This command is used to connect terminals to an operating container to control operations such as input, output, and debugging.
Syntax: docker attach container ID/container name
Example: docker attach reactjs
14) docker kill - This command stops and removes containers.
Syntax: docker kill container <container……>
Example: docker kill $(docker ps -q)
15) docker cp - This command helps in copying files from your local system to a docker container.
1. docker search - This command is used to search for docker images.
2. docker pull - This command pulls the image from docker hub.
3. docker push fosstechnix/nodejsdocker - This command pushes the image to the docker hub.
4. docker logout - Use this command to log out from the docker hub repository.
Conclusion:
With rapid changes in business, the need for a tool that can meet business requirements at that pace has also increased. Using Docker makes the containerization process simpler, faster, and reliable. Docker containers help to deploy softwares into production easily with limited human interaction. It enhances developer productivity dramatically by ensuring that if code works great in a test environment, it will almost certainly function in production.Thus we can say that the advantages of Docker are two-fold: reduction in Capital Expenditure and in Operational Expenditure. By learning Docker, you will not only stay abreast and competitive in your field but way ahead of your peers.
As a senior technical content writer for HRK tainings, srivalli patchava has a greater understanding of today's data-driven environment, which includes key aspects of data management and IT organizations. She manages the task of creating great content in the areas of software testing, DevOps, Robotic process automation. Connects with her on Linkedin and Twitter.