A Simple Guide to Docker Architecture

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by StarAgile

October 27, 2021
Category DevOps


If you want to become an expert in Docker, you must learn about the architecture of docker and the relationship between its components. Recognizing the diagram/structure of Docker architecture and the client-server models, such as Docker Host, Docker Engine, Docker Objects, etc., is essential for knowing Docker’s role in designing and developing applications.

Virtual Machines and Docker Containers - Differences

A virtual machine’s mechanism is fairly straightforward - it replicates a hardware server. It uses your system’s physical hardware for replicating the environment required to install applications. You can either make a real system virtual or process a virtual machine. If you use a real system, you can run an OS on the machine. In contrast, processing a virtual machine enables you to replace the real machine with the virtual one.

Docker takes your convenience level one step higher. Its software development solution is referred to as containers. Containers is an executable, lightweight software that possesses everything you need to run it efficiently. You can run Docker Containers on both Windows and Linux, as it is platform-independent. The best thing is - you can also run Docker Container inside a virtual machine.  

Hence, Docker Containers is an excellent, lean alternative to a virtual machine, as instead of abstracting the hardware server, Docker Containers work on the operating system’s kernel.

Here is the separate article for VMs Vs Containers

What Are The Top Advantages of Docker?

  • High RoI and Excellent Savings - Docker offers excellent Return on Investment (RoI) since it pulls down the costs to a great extent. Large organizations are fast moving towards Docker because it reduces infrastructure resources for operating similar applications, enabling higher savings and cost-efficiency.
  • Uniformity - The Docker architecture is consistent, standardizing the development, testing, and release cycles. Hence, all team members in the product pipeline share a similar wavelength. It minimizes the wastage of time and enhances productivity.

What is Docker Engine?

Docker Engine is a major part of the Docker architecture diagram. Docker Engine authorizes you to formulate, assemble, ship, and operate applications using the following units:

  • Docker Daemon - The Docker Daemon or Docker is a background process that decodes Docker API requests and controls Docker objects like volumes, images, networks, and containers. 
  • Docker Engine REST API - The Docker Engine API facilitates communication with the Docker Daemon. It can be accessed by an HTTP library or clients like curl or wget.  
  • Docker CLI - The Docker Command Line Interface (CLI) enables you to direct the Docker Daemon to build, run, or stop applications. It allows you to pull images from the registry and run them on the Docker host. 

The Architecture of Docker Simplified 

The Docker Architecture diagram employs a client-server model and contains elements like the Docker Client, Host, Objects, Network Components, and the Docker Hub or Registry. Let us understand the following in fragments:

What is Docker Client?

The Docker client authorizes users to interact/communicate with Docker. The Docker client can stay on the same host or engage with multiple daemons through a remote host. It can also deliver a Command-Line Interface (CLI), enabling you to issue application commands to the Docker daemon. General commands administered by a Docker Client are Docker build, Docker pulls, and Docker run.

What is Docker Host?

Docker Host enables a seamless and no-frills environment to create, test, and run applications. It contains the Docker daemon, Containers, Images, Network, and Storage. Since Daemon usually controls the container services and communicates via the REST API, it can conveniently pull and create container images.  

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What are Docker Objects?

Many objects are brought together to build your application. The primary requirements of Docker objects under Docker architecture are:

  • Containers - Containers is a lightweight software that contains everything you need to operate applications. It is illustrated by the image and other configuration options given at the beginning of the container, including storage capacity and network connectivity. Since containers occupy less space than virtual machines, their server density is higher than VMs. 
  • Images - Images exist as read-only binary templates and are utilized to build containers. The metadata in images explains the container’s necessities and capabilities. This image can be wielded on its own to create a container or customized to put in additional components to broaden the current configuration. 
  • Networking - Docker has two networks - default and user-defined. Docker is hugely popular because it enables application-driven networking and offers excellent flexibility. The three hosts in the default Docket network are none, bridge, and host. While the none and host ones are a portion of Docker’s network stack, the bridge network spontaneously prepares a gateway and IP subnet, allowing all containers to communicate with one another via IP addressing. When it comes to the user-defined networks, users generally configure networks like bridge network, overlay network, and Macvlan network. 
  • Storage - Although the container’s writable layer enables data storage, you may need a storage driver. However, the process might seem challenging. Docker generally provides four options for data storage - Data Volumes, Data Volume Container, Directory Mounts, and Storage Plugins.

What are Docker Registries?

Docker Registries serves you with the location from where you can download and save images. Public Registries are comprised of Docker Cloud and Docked Hub, whereas you can also utilize Private Registries. General commands of Docker Registries are – Docker Push, Docker Pull, and Docker Run.

Where Can You Implement Docker?

Docker is at one’s fingertips for implementation over a vast spectrum of platforms. On the desktop, it is available in Mac OS and Windows 10. It is also functional in various servers such as different Linux distributions and Windows Server 2016. Docker is also fit for cloud usage through platforms like Amazon Web Services, Microsoft Azure, IBM Cloud, Google Compute Platform, etc.

The Bottom Line

You now have most likely understood the different sections and components of the Docker Architecture and how they function. You can now realize the reason behind the surge in Docker containers’ popularity.

Docker enables smooth running of the infrastructure management, differentiates between the application and infrastructure layers, and facilitates the required portability, collaboration, and operation of the software delivery chain. The knowledge of the architecture of Docker from DevOps Classes where you can enable and receive the maximum from your containerized applications.