DevOps is a natural evolution of software development. DevOps is not just a tool, a framework, or just automation. It is a combination of all these. DevOps aimed to align the Dev and Ops team with shared goals.
A developer builds an application and sends it to the tester. But, the environments of development and testing systems are different; thus, the code does not work. There are two solutions to this: Docker and Virtual Machines, but Docker is far better in terms of performance, scaling, and efficiency.
Docker is a platform that has eased application development for both developers and system managers. Dockers have been used widely in many DevOps toolchains. Docker provides flexibility for the operational team, thereby reducing the risk of overhead. Dockers platform provides numerous features that make it popular among developers. Some features include application isolation, portability, security management, Ease of software delivery, scalability, etc. Let's discuss the basic docker commands in more detail, along with examples! You can refer to the best Docker courses for training related to docker and docker commands.
What is Docker?
Docker is a platform that enables the creation, deployment, and running of applications with the help of containers. A container is a unit of software that packages the code and all its dependencies together so that the application becomes runnable irrespective of the environment. The container isolates the application and its dependencies into a self-contained unit that can run anywhere. Container removes the need for physical hardware, allowing for more efficient use of computing resources. Containers provide operating-system-level virtualization. Additionally, using Docker commands, developers can easily manage these containers, enhancing their productivity and workflow efficiency.
A container is a runnable instance of an image. An image is a read-only template with instructions for creating a Docker container. You can create, start, stop, move, or delete a container using the Docker API or CLI. One can connect a single container to one or more networks and can also attach storage to it. A new image can also be created based on the current state of the container. Containers can be shared thereby ensuring that everyone who communicates with it will get the same container and that works in the same way. Here is the list of 50+ basic docker commands:
57 Essential Docker Commands List
Here are the top 57 essential/ basic docker commands with descriptions to learn and use.
Block until one or more containers stop, then print their exit codes
Let's understand a few of the above commands along with their usage in detail. The following are the most used docker basic commands for beginners and experienced docker professionals.
1. docker –version
This command is used to get the current version of the docker
Syntax
docker - -version [OPTIONS]
By default, this will render all version information in an easy-to-read layout.
2. docker pull
Pull an image or a repository from a registry
Syntax
docker pull [OPTIONS] NAME[: TAG|@DIGEST]
To download an image or set of images (i.e. A Repository) , Once can use docker pull command
This command is used to create a container from an image
Syntax
docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
The docker run command creates a writeable container layer over the specified image and then starts it using the specified command.
The docker run command can be used with many variations, One can refer to the following documentation docker run.
4. docker ps
This command is used to list all the containers
Syntax
docker ps [OPTIONS]
The above command can be used with other options like - all or –a
docker ps -all: Lists all containers
Example:
$ docker ps
$ docker ps -a
5. docker exec
This command is used to run a command in a running container
Syntax
docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
Docker exec command runs a new command in a running container.
Refer to the following article for more detail regarding the usage of the docker exec command docker exec.
6. docker stop
This command is used to stop one or more running containers.
Syntax:
docker stop [OPTIONS] CONTAINER [CONTAINER...]
The main process inside the container will receive SIGTERM, and after a grace period, SIGKILL. The first signal can be changed with the STOPSIGNAL instruction in the container’s Dockerfile, or the --stop-signal option to docker run.
Example:
$ docker stop my_container
7. docker restart
This command is used to restart one or more containers.
Use case 1: Developers write their code locally and can share it using docker containers.
Use case 2: Fixing the bugs and deploying them into the respective environments is as simple as pushing the image to the respective environment.
Use case 3: Using docker one can push their application to the test environment and execute automated and manual tests
Use case 4: One can make their deployment responsive and scalable by using docker since docker can handle dynamic workloads feasibility.
Let us take an example of an application,
When a company wants to develop a web application, it needs an environment where they have a Tomcat server installed. Once the tester set up a tomcat environment and test the application, it is deployed into a production environment. Once again the tomcat has to be setup in a production environment to host the java web application There are some issues with this approach:
Loss of time and effort.
Developer and tester might use a different tomcat versions.
Now, let's see how the Docker container can be used to prevent this loss.
In order to overcome the issues, docker will be used by a developer to create a docker image using a base image which is already existing in Docker hub. Docker hub has some base images available for free. Now this image can be used by developer, tester and the system admin to deploy a tomcat environment. In this way, Docker container solves the problem.
Docker Architecture
Docker architecture generally consists of a Docker Engine which is a client-server application with three major components:
Generally, docker follows a client-server architecture
The client communicates with the daemon, which generally takes up the task of building,running, and shipping the docker containers.
The client and daemon communicate using REST API calls. These calls act as an interface between the client and daemon
A command-line interface, Docker CLI runs docker commands. Some basic docker commands with examples are listed in the next section.
Registry stores the docker images
Conclusion
DevOps (development + operations) is an evolution born between developers and system administrators. One of the main tasks of DevOps is the automation and centralization of software development and deployment. One of the most popular tools that helps solve this task is Docker. To get a better understanding of Docker commands and more, enroll in Docker Kubernetes training.
Three main features of Docker products are the most distinguishing:
Quick deployment in a variety of environments
Greatly facilitated testing
Possibility of using Docker as a development environment.
Learning the top Docker commands is essential for any DevOps professional looking to streamline container management and deployment processes. As you continue to explore and learn more about Docker, keeping these commands at your fingertips will prove invaluable in your journey toward DevOps operational excellence.
Frequently Asked Questions (FAQs)
1. What do you mean by Docker command line?
Docker CLI (command line interface) is a command-line tool that is used to interact with the docker daemon. To get the list of commands either run docker with no parameters or execute the docker help command.
2. How many commands are there in Docker?
Docker has 13 Management commands and 41 general commands. One can run the docker command using the docker CLI tool. To list available commands, either run docker with no parameters or execute docker help.
3. What is an image in Docker?
An image is a read-only template with instructions for creating a Docker container. The container is a runnable instance, while image is a read only template of it. Using the command docker pull one can get the images from the docker registry.
4. How can I run a docker command?
One can run a docker command using the Docker CLI tool. Docker command line interface tool is preferably used to run docker commands Docker CLI tool can be installed along with docker.
Lakshmi Sushmitha V
Author
I am an ambitious software professional with 5 years of experience in the industry working with various tech gaints. I am an inquisitive person who always interested to explore the things and takeup challenges.Apart from profession , I love travelling,reading books,blogging and editing.
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