DOCKER

Docker is a popular platform for developing, shipping, and running applications in containers. Containers are lightweight, standalone, and executable packages that contain everything needed to run an application, including code, runtime, system tools, and libraries. Docker provides a standardized way to package and distribute applications, making it easier to deploy and manage software across different environments, from development to production.

Here are some key aspects and concepts related to Docker:

• Containerization:

?Docker uses containerization technology to isolate applications and their dependencies? ? ? ? ? ? ? from the underlying host system. This isolation ensures that an application runs consistently across various environments and eliminates "it works on my machine" issues.

• Docker Engine:

?The core component of Docker is the Docker Engine. It's responsible for building, running, and managing containers. The Docker Engine includes a server, an API, and a command-line interface.

• Docker Image:?

A Docker image is a read-only, template-like package that contains an application, its runtime, libraries, and other necessary components. Images serve as the foundation for creating containers. Docker images are typically stored in a registry, like Docker Hub.

• Docker Container:?

A Docker container is a runnable instance of a Docker image. Containers are isolated and can run on any system that supports Docker. They are lightweight and can be started, stopped, and moved with ease.

Benefits of using Docker include:

1. Portability: Docker containers run consistently across different environments, which reduces the "works on my machine" problem and streamlines the deployment process.
2. Efficiency: Containers are lightweight and share the host OS kernel, making them more efficient than traditional virtual machines.
3. Isolation: Containers provide process and file system isolation, enhancing security and resource management.
4. Scalability: Docker makes it easy to scale applications up or down by creating and managing multiple containers.
5. Reproducibility: Docker images and Dockerfiles allow developers to version their application components, ensuring reproducibility in different environments.

Some docker commands:

• docker –version (to get the currently installed version of docker)
• docker pull < image_name> ? (to pull images from the docker repository)
• docker run-it-d<image_name>? (to create a container from an image)
• docker ps (to list the running containers)
• docker stop<container_id>? (to stop the running container)
• docker kill <container_id>? ? (it kills the container by stopping its execution immediately)
• docker login ? (to login to the docker hub repository)
• docker push <username/image_name>? (to push an image to the docker hub repository)
• docker images? (to list all the locally stored docker images)
• docker build <path to docker file>? (to build an image from a specified docker file)
• docker logout [REGISTRY-URL]? ( to logout or to remove credentials)
• docker exec? (to execute a command in a running container)
• docker restart<container_id>? (to restart the stopped container)

Docker has become a fundamental technology in modern software development and deployment, enabling a consistent and efficient way to package, distribute, and manage applications. It's widely used in cloud computing, microservices architectures, and DevOps practices.