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Docker concept

Docker is a platform for developers and system administrators to build, share, and run applications using containers. The process of using containers to deploy applications is called containerization. Figure 1.1 graphically tells us that you can easily deploy your application through the docker container.

Containerized deployment is becoming more and more popular because containers have the following characteristics:

Flexible: even the most complex applications can be containerized.

Lightweight (Lightweight): containers leverage and share host kernels, which makes them more efficient than virtual machines in using system resources.

Portability (Protable): you can build locally, deploy to the cloud, and run anywhere.

Loose coupling (Loosely coupled): containers are highly self-sufficient and encapsulated, allowing you to replace or upgrade one container without interrupting others.

Scalability (Scalable): you can add and automatically distribute container copies in the data center.

Secure: the container has strict constraints and isolation on process applications without requiring any configuration by the user.

Figure 1.1

Mirrors and containers

Basically, a container is a running process that applies additional encapsulation features to isolate it from the host and other containers. One of the most important aspects of container isolation is that each container interacts with its own private file system, which is provided by the Docker image. The image contains everything you need to run the application, such as code or binaries, runtimes, dependencies, and any other file system objects you need.

Containers and virtual machines

The container runs on a local (native) Linux host and shares the host's kernel with other containers. It runs a discrete process and consumes no more memory than any other executable, so it is lightweight, as shown in figure 1.2.

By contrast, the virtual machine (VM) is a complete "guest" operating system that accesses host resources through hypervisor, as shown in figure 1.3. In general, vm generates other overhead in addition to the overhead consumed by the application logic.

Figure 1.2

Figure 1.3

Arrangement

The portability and replicability of containers means that we can move and expand our containerized applications between the cloud and the data center; containers effectively ensure that these applications will run in the same way everywhere, allowing us to take advantage of all these environments quickly and easily. In addition, as applications grow in size, we need tools to automate the operation and maintenance of these applications, to automatically replace failed containers and to manage them, making it easier for containers to update and reconfigure during their lifecycle.

Tools for managing, extending, and maintaining containerized applications are called orchestrations, and the most common orchestration tools are Google's Kubernetes and Docker's Swarm. Both orchestration tools are integrated in Docker Desktop, and we will use Docker Desktop to create the first choreographed containerized application in this guide.

Install Docker Desktop

The best practice for containerized application development is to use Docker Desktop. Docker Desktop will allow you to easily configure Kubernetes or Swarm on your local development machine, so you can immediately use all the features of the orchestration tool to develop your application without clustering.

To install Docker Desktop on Windows, please refer to the next article, "install Docker Desktop and enable Kubernetes on Windows 10".

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