Installation

Use

Commands

Hello in Docker

Docker as a Service

1. Why Docker Matters

Dealing with conflicts, dependencies, and inconsistent environments is a common headache in distributed applications. Docker comes to the rescue as a powerful tool, solving these issues by managing containers. Unlike traditional virtual machines, Docker uses Linux kernel features for resource isolation, allowing independent containers to run within a single Linux instance. This means no more hassles with starting and maintaining virtual machines, and your computer can run multiple containers simultaneously. Docker is especially useful for automation, offering benefits for integration tests and continuous delivery.

2. Key Concepts: Machines, Images, and Containers

To dive into Docker, it's crucial to understand three key terms: Docker machines, Docker images, and containers.

• Docker Containers: These are instances of specific runtime environments, such as simulating a machine with a particular database setup. Docker images result from executing commands in a script-like file called Dockerfile. Think of containers as processes—they can be created, stopped, died, or running.
• Docker Images: These represent predefined runtime environments created by executing commands in a Dockerfile. Docker allows you to have multiple containers of a specific Docker image, akin to the concepts of a program and its processes.
• Docker Machines: These are either local (virtual) or remote machines with Docker running, including cloud platforms like Amazon AWS or DigitalOcean. Each Docker machine has a specific IP address and can manage multiple Docker images and containers. The docker-machine command facilitates connecting to and managing these machines from your personal computer.

Docker Key Concepts

Docker, a powerful containerization platform, revolves around key concepts that form the foundation of its functionality:

1. Docker Images:
   • A Docker image is a read-only template that encapsulates an application and its dependencies.
   • Examples include images containing an Ubuntu operating system with Apache and a pre-installed web application.
   • Images are fundamental to creating Docker containers.
   • Docker simplifies image management, allowing the building of new images, updating existing ones, and downloading images from repositories like Docker Hub.
   • Docker images are the build components of Docker.
2. Docker Containers:
   • Docker containers can be likened to directories, holding everything necessary for an application to run.
   • Each container is instantiated from a Docker image.
   • Containers can be run, started, stopped, moved, and deleted, providing a dynamic and flexible environment.
   • Each container operates as an isolated and secure application platform, ensuring encapsulation.
   • Docker containers are the runtime components of Docker.
3. Docker Registries:
   • Docker registries function as repositories for Docker images.
   • These registries can be public or private stores where images are uploaded or downloaded.
   • Docker Hub is the prominent public Docker registry, offering a vast collection of pre-existing images for various purposes.
   • Users can create their images or leverage those crafted by others.
   • Docker registries play a crucial role in the distribution of Docker images.

Understanding these key concepts lays the groundwork for effectively utilizing Docker, whether it's creating, managing, or distributing containerized applications.

Linux Kernel : All the containers will have Host Kernel the same Host OS Kernel If you require a specific Kernel version then Host Kernel needs to be updated.