What is Docker?

What is Docker? As this platform takes the IT industry by storm, we take a closer look at what is a Docker container,  how it works, what is Docker software and what capabilities it provides.

Docker is an app containerization and management platform. It is an open-source and free software initially developed by Docker, Inc. The company still provides Docker-as-a-Service, titled Docker Enterprise, enabling their customers to run their apps, Big Data systems, microservices and other workflows in a high-availability ecosystem.

However, as Docker Registry is open, usually the businesses don’t opt for paid Docker Enterprise subscription, but go for either training an in-house Docker expertise or hiring an external contractor to manage their Docker operations and using Docker in the process of software development https://itsvit.com/blog/vagrant-vs-docker-better-software-development-environments/.

Docker containers — building blocks of modern cloud infrastructure

What is a Docker container then? It is an envelope of code containing all the runtime needed to run an app — OS, binaries, libraries, drivers, appropriate versions of management software and monitoring tools, etc. Depending on the app and runtime weight, the container might be as small as several megabytes, or as large as hundreds of megabytes.

Docker containers are built (or composed using dockercompose command) from Docker Images, which are stored in Docker Registry. The Registry contains thousands of images, composed by teams across the globe and indexed for convenience. Thus said, it is quite easy to find a Docker Image containing everything you need, up to the correct versions of the software — and adjust it to your needs.

Once the image library is accomplished, you can easily compose the containers using he required versions of images. However, this is where the peculiarities begin.

What is Docker software limited by?

First of all, Docker images cannot be easily deleted, which makes maintaining the Registry quite a complicated task. Secondly, Helm charts are a must in order to manage a library of images for multiple app versions. Thirdly, if your resource managers like GridEngine don’t have native support for containers, finding workarounds will prove quite a challenge.

There are multiple other irritating concerns, like possible security breaches when putting third-party code inside a multi-tenant container environment, or trying to containerize an app that requires kernel modifications, or containerizing a customer-facing app with a GUI, etc.

Thus said, Docker containers are not by any means a panacea. They do have their shortcomings, but their benefits outweigh all the trouble and make app containerization the primary task for many businesses worldwide.

Docker container benefits

What is Docker container capable of? Well, here are Docker container benefits to list a few:

  • it is immutable once the image is created;
  • it can be launched, rebooted or deleted within milliseconds;
  • thousands of containers can be launched simultaneously using Kubernetes or Docker Swarm
  • containers are secure by design and can be easily monitored, as interaction with ELK stack or Prometheus+Grafana is available out of the box.

There are multiple other advantages, which become obvious depending on the project type.

Final thoughts on what is Docker and why it rocks

We hope that now you have a basic grasp of what is Docker software and what it is useful for. The only issue with Docker is the lack of experienced specialists. However, if your DevOps engineers can work with containerd Linux technology and understand the principles of code envelopes, they must be able to learn how to use Docker containers pretty fast.

If you do not have DevOps engineers, however, the best solution would be contacting a Managed Services Provider with a decent expertise of dealing with Docker, Kubernetes and the rest of DevOps tools. Good luck with your business projects!

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