What is Docker? How Does It Work?

What is Docker? How Does It Work?

Docker, prepared as an open-source project for application development, is a topic of curiosity for many programmers regarding what it is and how it is used. Docker is used to create containers on Linux, macOS, and Windows operating systems. Docker, an open-source platform that simplifies the organization and deployment process of application projects, is frequently used by programmers. Initially introduced as DotCloud in 2008, Docker was introduced and released at PyCon in 2013. Docker stands out as a popular platform preferred by those who follow innovative software technologies and want to simplify the application development process.

What Are the Fundamental Components of Docker?

Programmers and companies wanting to learn the answer to the question of how Docker, which finds application areas with container technology, is installed, may benefit from learning the general operational structure of this program first. When Docker’s general operational structure is examined, some terminological concepts that need to be known are listed as follows;
 

• Docker Engine: It can be defined as server technology that runs containers, the fundamental mechanism of the program, and supports various Linux and Windows operating systems.
   
• Docker Image: For running applications, it is necessary to package images with the container. With Docker Image, you can either make your own images or use images created by others.
   
• Dockerfile: It can be defined as the name of the config file needed to create an image in the application project. In container configuration; network connection point, language, and file location like many instructions necessary while creating images are layered with Dockerfile.
   
• Docker Hub: After the images are created, Docker Hub is used for storage and sharing.
   
• Docker Registry: Indicates the location where images are stored on Docker Hub. Similarly to Github, Docker Registry allows the images created to be used by others.
   
• Docker Daemon: Docker Daemon, which runs and distributes containers, manages images. This component, which operates on the host computer and has a mediatory role in the operating system, can be defined as a kind of background service.

How Does Docker Work?

Docker, an active program in the organization and distribution process of applications, has its working mechanism as one of the primary topics of curiosity for developers. Docker can be installed on all servers that support the operating system. However, its working mechanism consists of some unique stages in Windows and Linux operating systems. You can download the installation file from Docker's own website and complete the installation process with the steps suitable for your computer's operating system.

Docker Installation Stages on Linux

• You should go to the Docker website and review the operating system requirements.
   
• After determining that Docker is suitable for download on Ubuntu, you can delete all old versions of Docker.
   
• After the loading and running of the script file are completed, you can complete the installation stage by checking whether Docker is installed.

What Are the Docker Commands?

Those who want to learn the answer to the question of how Docker is used should know what the program's commands are. After Docker is installed on the computer, main command scripts are used. The main Docker commands are listed as follows;

• Build: Installs and loads images.
• Login: By logging into the Docker registry, you can pull images.
• Pull: Loads images from Docker Hub.
• Rmi: Unused images are deleted.
• Search: It is used to find images whose name is not known.
• Run: It is used to run downloaded images.
• Images: It is used to display images.
• Exec: It is used while processing in the container.
• Docker PS: This command is used while listing containers.
• Logs: You can use this command to apply the log to the screen through the container.
• Rm: It is used to delete containers.
• D: It is used to start the image in the background.
• Stop: It is used to stop the selected container.

What are the Advantages of Docker?

The questions such as what Docker is and what it is used for, help to easily understand how the program is used. The program is preferred to ease the application development process and effectively use the operating system resources. Docker, which is used by millions of developers to eliminate the damage that virtualization platforms cause to the operating system, has the following advantages;

• It rescues virtual machines from slow operating systems and launches them within seconds.
   
• Unlike the use of virtual machines, Docker, which offers a speed advantage, promises its users to develop more applications in a short time.
   
• In application projects requiring work on different servers, there is no need to set up different environments by downloading Docker images.
   
• There are many tools available for managing containers created with Docker. You can automate resource management with Kubernetes technology.
   
• With Docker, you can run applications in multiple environments simultaneously. Applications running on different operating systems prevent any problems from occurring.
   
• Docker can work seamlessly with CD and CI applications as it accelerates sharing.
   
• With Docker, there is no need to remove the entire application when a change needs to be made on the application.
   
• Compared to virtualization platforms, you can develop more applications with less resource consumption.
   
• It prevents resource wastage as it operates on cloud systems. Also, data volumes are lower, hence it performs less memory usage compared to virtual machines.
   
• Resolving issues in application projects and reverting operations are easier in small container configurations.
   
• Supports all three operating systems: Windows, Linux, and macOS.
   
• It's easier to move from local development machines to other platforms.
   
• It can be integrated with multiple tools and cloud services like Microsoft Azure, Kubernetes, AWS, and Ansible.

What are the Differences Between Docker and Virtual Machine?

There are many aspects that separate the virtual machine and Docker platform from each other. A primary example can be given regarding operating systems. Virtual machines have full operating systems while Docker has a minimized and shared operating system. Docker's level of isolation, where resource consumption is minimized, is lower than the virtual machine's level of isolation. While a virtual machine needs minutes to operate, Docker completes the installation process within seconds. While there are no versions in a virtual machine, the versioning of the Docker platform is quite high. Sharing application projects is harder in a virtual machine, but it can be easily done on the Docker platform. Both Docker and virtual machine have advantages and disadvantages. However, in the application development process and more efficient use of operating systems, many features of Docker stand out as advantages.

Why Do Developers Use Docker?

There is a need for a container structure to use Windows, macOS, and Linux operating system resources. Some virtualization platforms are preferred for resources such as RAM and processors in the computer operating system to be used simultaneously on the same system. This situation leads to unnecessary and incorrect use of operating system resources. Container configuration, on the other hand, prevents unnecessary resource usage of virtualization platforms. Docker, which uses container technology, distributes resources in the operating system, helping applications to run smoothly. Therefore, the answer to the question of what Docker is and why it is used can be given as easy installation of web applications and minimizing server costs. Developers who want to provide multiple virtualizations on the same operating system can use the Docker platform designed with container technology.

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