What Is Docker? Explanation Of The Tool

Containers: A Quick Overview

As Docker is all about containers, it’s wise to get familiar with them first. 

They can be considered a small fraction of software, which is executable and features the libraries, app or solution code snippets, and module dependencies. 

It’s the responsibility of Containers to ensure that all such units are accessible from anywhere and in any ecosystem. They help the application achieve virtualization and process isolation.

The concerning capabilities like control-groups, namespaces, and other resource visibility are important as they enable multiple app modules to share the single instance resources in a manner that concerns the hypervisor and permits VMs to share resources like memory and CPU of one hardware server.

This strategic resource sharing offers all the leading capabilities and benefits of VM, minus their loopholes.

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What Is Docker?

It is a globally recognized platform that is used extensively to do container management. It’s an open-source tool providing every capability and resource for their development, deployment, implementation, update, and management.  

As containerized apps are in huge demand, Docket is now used extensively. Even though one can develop containers without the help of Docker, the process, this way, becomes tedious. 

The platform lets developers work directly with Linux and other key OSs. Hence, tons of development hassles are reduced, and containerization becomes faster and easy than ever. No wonder why over 13 million developers are using this leading platform.

The software is offered by Docker Inc., which looks after all the version update releases, troubleshooting, and launch of new products related to the software.

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A Brief History

The grandeur that Docker owns presently started in 2008 when Solomon Hykes, Kamel Foundi, and Sebastien Pahl, founded Docker Inc. in Paris. The startup made it into the headlines instantly. In its early stage, the platform was offered as a PaaS tool by DotCloud. Back then, it was mainly used for democratizing the platform’s underlying/core containers.

Hykes presented Docker to the world at the PyCon conference in 2013. He confirmed that he developed it to fulfill the constant demand from the developer community to reveal DotCloud’s core technology. In March 2013, it was made available as a free-to-use tool operating in the LXC ecosystem.

Nearly one year after its public release, Docker 0.9 was made available. This new version featured libcontainer, a Go programming-based component. With each passing day, its adoption becomes wider than before. 

In 2014, Microsoft and Amazon adopted Docker. Oracle Cloud released its potential in 2015 and offered dedicated Docker container support. The Mody project was later released in 2017. 

In 2020, this tool started offering support for WSL2 to Windows 10 versions. Presently, Docker Kubernetes is very famous and is used widely.

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Why Use Docker?

This solution is gaining huge popularity amongst the developer community, which isn’t baseless. This platform provides a wide range of features and facilities, such as :

• Uninterrupted access to the native containerization capabilities of Linux, Ubuntu, and other operating systems. The best part is that it won’t require heavy commands and can fully automate the process using the APIs.
• Seamless portability, which is missing in LXC containers. Docker makes containers run without any modification and make their runs on any cloud ecosystem and operating system.
• Light and granular updates are easy using this platform, as it enables multiple processes to merge in single containers.  
• The tool can mark do quick versioning and roll back the versions easily. It can even help one discover who and how the version was built. That’s not enough; it can upload the deltas between the current and newly launched Docker version.
• Fully automated generation is possible as Docker uses the application source code and starts developing containers.
• Great reusability leads to less tedious development. one can use containers as base images or as templates to create new images.
• Version tracking is easy and hassle-free. The tool can track everything related to container-image versions and even roll back previous versions.  
• Distributed libraries that feature a wide range of contributed containers.
• Great compatibility across the operating systems and cloud ecosystem. It works on Windows, macOS, Linux, and many more. It even works seamlessly on cloud ecosystems like AWS, IBM Cloud, Azure, etc.

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Docker Terms

Docker is made of multiple parts and components. As you plan to use the tool, you need to understand what all its key components are and what these terms refer to. Have a look at key terms for your reference.

• Docker images

These files feature easy-to-execute application source codes, libraries, tools, and dependencies that are crucial for container usage, running, and management. As one runs the Docker Image, it takes the form of one or multiple instances of the concerned container.

These images can be built from scratch or by using readily available repositories. At the structure level, they feature multiple layers where each layer resembles the image version. With each structural change in the Docker image, a new layer is topped above the previous layer.

• DockerFile

It is like the building block of a Docker-container, as each container starts as a text file only. This text file features steps to explain how a Dockerized image should be formed. DockerFile automates container generation and is mainly a primary source to access CLI instructions for Docker Engine.

• Docker containers

These are always-active instances of Docker-based images. They are live and easy-to-execute components that users can use for interaction.

• Docker Desktop

It’s an app for Windows and Mac devices featuring components like Docker CLI, Docker Engine, Kubernetes, Docker Compose, and many others. Its users will have direct access to Docker Hub.

• Docker daemon

It’s an extensive Docker service designed to develop and manage images based on the provided client commands. At the very basic level, the Docker daemon is the central control unit for its deployment.

• Docker registry

This is a highly scalable storage and distribution system. It’s free to use and mainly deals in Docker images. With its help, it’s easy to monitor the image versions.

• Docker Hub

It is an extensive collection of Dockerized Images, available to all for general usage. Averagely, it features over 100,000 container-images that organizations and developers can use in their projects. Docker Hub users can share Docker images among themselves without any restrictions.

Docker Advantages and Disadvantages

Like any other technology, Docker also has evident advantages and drawbacks. As you plan to use this tool, it’s important to learn both these aspects of this tool so that you know what you will gain and what you will lose.

Let’s talk about the benefits and advantages that Docker brings to the table, according to the Docker Documentation. First, let’s talk about its minimalist design and great portability. 

• It allows developers to run and manage applications in the native ecosystem so that they remain less complex. As it can keep applications isolated, it helps in creating minimalistic applications that are easy to port and can grant great granular control.
• ‍Composability: Developers can easily compose the building block as a unified unit featuring switchable parts that are useful for speeding development and quick debugging.  
• ‍Scalability and orchestration are easy because Docker-containers are highly lightweight and can be launched in the bunch so that services are easy to scale.

Along with these benefits, you get to deal with the below-mentioned drawbacks as you use Docker-containers.  

• They are not as useful as virtual machines as elements are not strictly isolated. In Docker, containers only utilize a part of OS resources.
• You don’t get to use the bare-metal speed with them. Even though they are highly lightweight, they fail to attain bare metal speed and come with evident high-performance expenses.
• They are stateless as they are booted and operated using an image explaining the key contents.
• This image is immutable and remains unchanged once created. Also, the container-instance is transient, and when it’s pulled off the system, its linked memory is deleted once and for all.

To make more of this open-source tool, you must find a way to fix the drawbacks.

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Docker Security

Clearly, Docker is the foundation of container-based applications. Hence, its security is important. With or without its use, containers have certain issues and weak security profiles. As stated above, they are not as isolated as virtual machines. They share the OS host. So, if the concerned host and its related OS are under attack, all the containers will be at risk.

The most common container vulnerabilities are unwanted access to Docker images, network traffic hacking, and malware insertion. Even though the platform tries its best to improve containers’ security, it’s not 100% flawless.

The most common methods to strengthen Docker container security are:

• To execute them with VMs to trim down the security flaw impacts
• Using low-profile VMs like Kata Containers and gVisor as they demand fewer overheads as compared to traditional VMs
• Using an NGINX-based filtering node as its better alternative. With this option, you have a high-strength Docker security profile that you can customize according to the need of the hour. Wallarm provides a wide range of such filtering nodes. Read about ‘Running Docker NGINX-based image’, click here.

Conclusion

As containers are used widely, Docker is becoming synonymous with their quality and effective use. The guide explained Docker in detail. As you plan to rely heavily on Docker networking, we strongly recommend adopting best cybersecurity practices. Docker commands, when not secured, can cause serious hassles.