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What is Docker? All you need to know

Luther Riggs

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If you are in software development or deployment fields, you may have heard the words Docker or Docker container. If you are working in a field close to it, and you do not know what Docker is, do not fear! We will dive into Docker in detail,  and help you stay up to date. In addition, we will also do a quick comparison between Docker containers and Virtual Machines

What is Docker?

Docker is a Linux container technology. Now the question is, what is a container? Simply put, a container is a standardized unit of software that bundles codes and applications. Docker containers have everything – code, run time, system tools, libraries, and settings. This lets applications run smoothly, and across different environments.

It is easy to build, and share applications using Docker. In comparison to a laptop, operators can build and test at scale, in production, public clouds and more, using Docker containers. They are flexible, portable, and easy to deploy. 

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Per their website, “Docker’s container platform and services are used by millions of developers and more than 750 Global 10K commercial customers including ADP, GE, MetLife, PayPal, and Societe Generale.”

What is Docker used for?

Docker’s technology initially started off as an open-source Docker engine in 2013. It uses the Linux base structure. The technology allows both developers and system admins to separate operational factors from infrastructure.

Docker containers are:

  • Standard
  • Portable
  • Secure

Firstly, Docker created the industry standard for containers. As a result, these containers can be run anywhere. Secondly, Docker containers share the machine’s OS system core and do not require an individual OS per application. Thirdly, all the applications are completely separate and safe in the container.

Additionally, the technology can be used to build and deploy updates as needed. It is also scalable, which means you can increase the capacity of the containers as needed. Docker containers can also be stacked in combination with other applications. You can use products like Google Cloud Platform (GCP), Microsoft Azure, Oracle Container Cloud Service, AWS ECS Elastic container storage and ECR elastic container repository in combination with Docker for your deployments.

How to use Docker

Overall, Docker architecture uses client-server communication. Running Docker starts with preparing the base OS to run the Docker engine. Docker’s website has a tutorial on how to use technology. They have a step-by-step introduction to all parts of the solution. Docker containers are built from Docker images.

A docker file contains all the necessary processes to create a docker image. You can download the docker image. After that, you can create a notepad on either WordPress or DocuWiki. To summarize, these are the processes involved:

  • Install Docker
  • Use Docker Compose
  • Get Docker Machine
  • Create Containers
  • Use the published image
  • Confirm that the image works in the container
  • Ensure the final version is ready
  • Choose Docker Engine/ Enterprise
  • Deploy

Advantages and disadvantages of using Docker

Containers vs Virtual machines

Before getting into the benefits of Docker, it is important to distinguish this technology from Virtual Machines. A virtual machine mimics an actual computer, giving the user the feeling of working on the host OS. Multiple virtual machines can run on the same physical computer at the same time. On the other hand, containers imitate the OS, instead of the hardware. Containers take up less space than VMs and can handle more applications.

Advantages of Docker container:

Docker allows applications to be released easily without worrying too much about the target environment. Here are some of the advantages of using Docker. First and foremost, users can create a reliable scenario, which allows them to build and test applications. Admins can create consistent development and production systems. Second, the applications can be isolated from others, and run anywhere. Third, the containers are portable, and all factors can be controlled. Lastly, Docker increases server efficiencies and reduces licensing costs. 

Disadvantages:

While its advantages are many, there are some negatives associated with using Docker containers as well:

  • Performance overhead
  • Some products do not work with other applications
  • Shutting down Docker deletes data forever
  • Graphical applications do not run well

Based on each organization’s needs, the advantages may be enough to ignore the disadvantages. Or sometimes, the business may need all the points mentioned in the cons of using Docker containers. These companies may choose a different option instead of Docker.

How to install Docker container

There are three versions of Docker available, namely:

  • Enterprise
  • Engine – Community
  • Engine – Enterprise

The versions are based on the scale and size of the teams using it and the projects that will be run on the tool.

 Steps to install Docker on Linux

The Docker container can run on any operating system version higher than Linux 3.8. These are the steps to install Docker on Linux:

  • Verify that the version is higher than 3.8 and update the software if not
  • Install required certificates to work with Docker 
  • Add GPG key to ensure data security
  • Input relevant site to docker.list 
  • Update the packages in the system 
  • Get the Linux-image-extra-* kernel packages
  • Install Docker 

Steps to install Docker container on Ubuntu

There are some conditions to install Docker on Ubuntu 18.04. These are:

  • Ubuntu 64-bit operating system
  • A user account with Sudo permissions
  • Command-line/ terminal 
  • Docker software repositories

The steps to follow to install Docker on Ubuntu are:

  • Update the local software database to latest versions
  • Uninstall any old versions of Docker 
  • Install Docker 
  • Setup and run Docker service with start and enable scripts
  • Verify the installed version with docker — version code

While the above process is correct, the official Docker website does not offer technical support. You could bypass this by installing Docker from the official repositories.

Conclusion

You can create, run and share your applications securely on Docker containers. They offer optimum resource distribution and isolation for your releases. As mentioned previously, they are portable and increase efficiency. Docker containers also save costs. Docker applications are used widely in government, education, and financial services industries.

In conclusion, when choosing deployment tools for your business, you can choose based on scale and complexity. Some teams want application packaging and delivery solution to deploy to the cloud, whereas other teams work in large applications. It’s your choice, choose wisely!

Luther is a professional Software Engineer and passionate technology Blogger. His main area of research is Software and Business Development.

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