Docker And Containers

A container is a lightweight, standalone, executable package that includes everything needed to run a piece of software, such as code, runtime, libraries, and dependencies, isolated from the host system.

Containerization is a virtualization method that packages an application and its dependencies into a container, enabling consistent deployment across different environments without hypervisor overhead.

Docker is an open-source platform that automates the deployment, scaling, and management of applications inside containers using containerization technology.

Containers share the host OS kernel and are lightweight, starting in seconds, while virtual machines include a full guest OS, making them heavier and slower to boot.
Containers virtualize at the OS level; VMs at the hardware level.

A Docker image is a read-only template containing the application code, libraries, dependencies, and configurations needed to create a container.

A Docker container is a runnable instance of a Docker image, providing an isolated environment for running applications.

Docker Hub is a public registry service where users can store, share, and manage Docker images for easy access and distribution.

On Ubuntu, add Docker's official GPG key, set up the repository, update package index, and install via sudo apt install docker-ce, then start and enable the service.

The Docker daemon (dockerd) is a persistent background process that manages Docker objects like images, containers, networks, and volumes via the Docker API.

docker images or docker image ls displays a list of locally available Docker images with details like repository, tag, ID, and size.

docker pull <image> downloads a Docker image from a registry like Docker Hub to your local machine for use in creating containers.

Use docker build -t <name:tag> . in the directory containing the Dockerfile; the . specifies the build context as the current directory.