This repository contains the materials for a hands-on lab designed to introduce the fundamentals of Docker.

This lab introduces Docker, an open-source platform for creating, deploying, and running applications in isolated environments called containers. Containers package application code with all necessary libraries, dependencies, and settings. The instructions for building a Docker image, which serves as a blueprint for creating a Docker container, are specified in a Dockerfile.

Containers can run on any environment—Windows, Mac, or Linux—provided a container runtime, like Docker, is installed. In this lab, Docker is pre-installed for you. For installation at home, refer to the following links:

• How to Install Docker Engine on Windows
• How to Install Docker Engine on Mac
• How to Install Docker on Linux

In this lab, you will explore the following topics:

• Verifying that Docker is installed correctly
• Creating containers using Docker images from Docker Hub
• Introduction to common Docker CLI commands for managing containers and images
• Creating a Dockerfile for an existing application and building it into a Docker image

There are many benefits to using Docker and containers. Here are a few advantages:

Containers ensure applications run consistently across various environments. There's no need to worry about installing libraries or operating system compatibility; just make sure Docker is installed. You can then download or build your image using a Dockerfile and seamlessly run it in a container.

The following diagram shows a virtual machine versus a container environment:

In a virtual machine (VM) environment, each VM has its own operating system and kernel, along with the application and its dependencies. VMs run on a hypervisor, which manages them. While VMs are more isolated than containers, their large size and need to boot a full OS make them resource-intensive and slow to start.

In contrast, containers on the same host share resources and the OS kernel, making them smaller, more resource-efficient, and faster to start, as they don't require booting a complete OS. The container runtime manages the lifecycle of containers, allowing many containers to run simultaneously on a host due to their reduced size.

Here are definitions of some common Docker terms you will see in this lab:

• Image

  A Docker image is a read-only template that includes all of the files, binaries, libraries, and configurations needed to create a container. Multiple containers can be created from the same image. Once a Docker image is created, it cannot be modified. Instead, you can create a new image or layer changes on top of it to form a new image.

• Container

  A Docker container is a running instance of a Docker image. Each container can have its own unique data and state and is isolated from other running containers.

• Docker Engine

  The Docker Engine is the core component of the Docker platform, enabling the creation, management, and execution of containers. It consists of the following components:

  • Docker Daemon (dockerd): A background process running on the host machine, responsible for managing Docker objects such as images and containers. It handles lifecycle operations like starting, stopping, and removing containers and images.
  • Docker CLI: A command-line interface used to interact with the Docker Daemon for building, running, and managing containers.
  • REST API: A programmatic interface to interact with the Docker Daemon, enabling automation and integration with other tools and systems.

• Dockerfile

  A Dockerfile is a special text file containing instructions and commands to build a Docker image. Each instruction creates a new layer, and multiple layers are stacked to form the final image at the end of the build process.

• Docker Hub

  Docker Hub is a cloud-based registry service provided by Docker for storing, sharing, and distributing Docker images. You can share images publicly or privately with authorized users. Alternatively, you can set up a local Docker registry to keep images within your company's infrastructure, particularly when data requirements restrict storing container images outside the organization.

This lab is to familarize participants with the basics of Docker. For any design related questions please contact your representative at Javid Alizada