Plainly put, Docker is an open-source technology used mostly for developing, shipping and running applications. With it, you can isolate applications from their underlying infrastructure so that software delivery is faster than ever. Docker’s main benefit is to package applications in “containers,” so they’re portable for any system running the Linux operating system (OS) or Windows OS. Though container technology has been around for a while, the hype around Docker’s approach to containers has moved this approach to the mainstream as one of the most popular forms of container technology.
The brilliance of Docker is that, once you package an application and all its dependencies into a Docker run container, you ensure it will run in any environment. Also, DevOps professionals can build applications with Docker and ensure that they will not interfere with each other. As a result, you can build a container having different applications installed on it and give it to your QA team, which will then only need to run the container to replicate your environment. Therefore, using Docker tools saves time. In addition, unlike when using Virtual Machines (VMs), you don’t have to worry about what platform you’re using – Docker containers work everywhere.
Now, your intrigue about Docker containers is no doubt piqued. A Docker container, as partially explained above, is a standard unit of software that stores up code and all its dependencies, so the application runs fast and reliably from one computing environment to different ones. A Docker container image is a lightweight, standalone, executable package of software that has everything you need to run an application – code, runtime, system tools, system libraries, and settings.
Available for both Linux- and Windows-based applications, containerized software will always run the same, regardless of the infrastructure. Containers isolate software from its environment and ensure that it works uniformly despite differences.
A Docker container runs on any machine that supports the container’s runtime environment. You don’t have to tie applications to the host operating system, so both the application environment and the underlying operating environment can be kept clean and minimal.
You can readily move container-based apps from systems to cloud environments or from developers’ laptops to servers if the target system supports Docker and any of the third-party tools that might be used with it.
Most business applications consist of several separate components organized into a stack—a web server, a database, an in-memory cache. Containers enable you to compose these pieces into a functional unit with easily changeable parts. A different container provides each piece so each can be maintained, updated, swapped out, and modified independently of the others.
Basically, this is the microservices model of application design. By dividing application functionality into separate, self-contained services, the model offers an alternative to slow, traditional development processes and inflexible apps. Lightweight, portable containers make it simpler to create and sustain microservices-based applications.
Författare: Shivam Arora