Docker is an open-source virtualization technology known a containerization platform for software containers. These containers provide a means of enclosing an application, including its own filesystem, into a single, replicable package.
Initiated in 2013 by Solomon Hykes, the Docker platform was built specifically for Linux operating system and has since achieved widespread popularity among developers and cloud service providers for its ability to simplify and automate the creation and deployment of containers.
Because container technology allows developers to package an application, along with all of its dependencies, into a standardized unit, containers are quickly becoming a preferred approach to virtualization. Automation through Docker has been critical to that success.
What Is a Docker Container?
Containers are not a new technology. Like virtual machines (VM), they are a form of virtualization that has been around for years. However, where they stand apart from a VM is in the size of their footprint.
While a VM creates a whole virtual operating system, a container brings along only the files that are required to run an app and that aren’t already running on the host computer. They can run lean by sharing the kernel of the system they run on, and where they can, they even share dependencies between apps. Ultimately, that means smoother performance, smaller application size, and faster deployment.
What Is Docker Engine?
The Docker container is the component that delivers efficiencies, and Docker Engine is what makes it all possible. In short, a Docker container is run from an image file — essentially a file that’s created to run a particular application on a particular operating system. Docker Engine uses that image file to build a container and run it.
The lightweight Docker Engine, and the easy automation it provides, is the real innovation that has made Docker a successful tool. Its ability to automate deployment of containers has brought the technology to prominence. It offers the benefit of greater scalability in virtualized environments, and it allows for faster builds and testing by development teams.
How Does Docker Contribute to a DevOps Environment?
DevOps teams gain a number of advantages by using Docker. With instant OS resource startup and enhanced reliability, the platform is well-suited to the quick iterations of agile development teams. Development environments are consistent across the whole team, using the same binaries and language runtime.
Because containerized applications are consistent across systems in their resource use and environment, DevOps engineers can be confident an app will work in production the same as it does on their own machine. Docker containers also help to solve compiling issues and simplify the use of multiple language versions in the development process.