Published on April 08, 2023
Explore the benefits of lightweight, portable, self-contained Docker containers for software development, application deployment, and business agility.
Software is described in a book published in 1981 as “nebulous and difficult to grasp.” That was true in 1981, and it remains true today. You will find it difficult to deploy, manage, and run software, regardless of whether it is an application that you purchased or one that you built yourself.
The Docker container provides an effective means of managing software. In Docker, you can wrap up an application in such a way that its deployment and runtime issues – how to expose it on a network, how to manage its storage, memory and I/O, how to control access permissions – are handled outside of the application itself, ensuring consistency across all “containerized” applications. Any OS-compatible host (Linux or Windows) that has the Docker runtime installed can run your Docker container.
Additionally, Docker offers many other benefits in addition to encapsulation, isolation, portability, and control. The size of Docker containers is small (megabytes). They begin immediately. They have built-in mechanisms for versioning and reusing components. Using the Docker Hub or a private repository, they can be easily shared.
Docker containers are also immutable, which provides both security and operational benefits. Any changes to a container must be deployed as a new, differently versioned container.
We will explore how Docker containers simplify the development and deployment of software; what issues containers address, how they address them, when they are appropriate, and when they are not.
Before Docker containers
Enterprise software has traditionally been deployed either on “bare metal” (i.e. on a system that is fully controlled by the underlying hardware) or in a virtual machine (i.e. on a system that shares the underlying hardware with other “guest” systems). The difficulty of moving and updating software on bare metal made it difficult for IT to respond nimbly to changes in business requirements.
Then came virtualization. Virtualization platforms (also known as hypervisors) enable multiple virtual machines to share a single physical system, each virtual machine simulating the behavior of an entire system, including its own operating system, storage and I/O. By cloning, copying, migrating, and spinning up or down VMs, IT could respond more effectively to changes in business requirements.
By consolidating more virtual machines onto fewer physical machines, virtual machines helped reduce costs as well. In order to save even more money, legacy systems running older applications can be converted into virtual machines and physically decommissioned.
However, virtual machines still pose a number of challenges. Virtual machines are large in size (gigabytes), and each one contains a full operating system. A single system can accommodate only a limited number of virtualized applications. The process of provisioning a virtual machine still takes a considerable amount of time. Finally, the portability of virtual machines is limited. In the long run, virtual machines cannot provide the speed, agility, and savings that fast-moving businesses require.
Docker container benefits
Containers work similarly to virtual machines, but on a much more detailed and granular level. Both the underlying operating system and other containers are isolated from a single application and its dependencies — all of the external software libraries that the application requires to run.
All containerized applications share a single, common operating system (either Linux or Windows), but they are compartmentalized from one another and from the system at large. In order to achieve compartmentalization, the operating system provides the necessary isolation mechanisms. This set of mechanisms is wrapped in a convenient set of interfaces and metaphors for developers by Docker.
Docker containers offer a number of benefits. The following are some of the major advantages of Docker and containers.
