Docker is a tool that is designed to create, deploy and run applications easily by using containers. The containers allow a developer to wrap up an application with all essential parts i.e. libraries, dependencies and ship it all out as one package. The developer can be assured that the application will run on any Linux machine regardless of any customized settings by doing this. The mechanism is abstracted i.e. hiding the implementation. In a nutshell, it is an extension of Linux Containers (LXC) which is a unique kind of lightweight, application-based virtualization.
Docker is compared to that of virtual machine (VM). The difference lies in the fact that rather creating a whole virtual operating system, Docker allows applications to use the same Linux kernel as the system, they are running on. It only requires applications to be shipped with things not already running on the host computer. The above significantly boosts performance and reduces the application size. It is an open source which means that anyone can contribute to Docker and extend it to meet their own needs if they need additional features that aren’t available out of the container. Even though it says it supports windows and Mac, Docker is primarily Linux oriented.
Docker is mainly designed for developers and system administrators. It serves as a part of many DevOps (i.e. developers and operations). For developers, they can focus on writing programs without worrying about the system, it’s running on. The developers are allowed to use programs that are stored in Docker container as a part of their application. For operations staff, it provides flexibility and reduces the number of systems needed because of its lower overhead and small footprint. The repeatable nature of Docker images helps to standardize their production code and configurations.
Docker is also used for continuous integration purpose. eBay focuses on incorporating it into their process to standardize deployment across distributed network of servers, running as a single cluster. The application dependencies inside containers are isolated to address the issue of each server that has different software versions and special hardware. The above fact clarifies that the host Operating System does not need to be the same as the container Operating System. The end motive is to have different hardware and software systems running as a single Mesos cluster.
Docker also serves as a security of a sandbox. A Docker-based sandbox named as CompileBox was released to run untrusted code and return output without risking the host. Basically, the malicious codes that attempt to destroy the system would be limited to the container. It can be created and destroyed quickly as needed.
A number of companies and organizations are coming together to bring Docker to desktop applications. Microsoft is trying to implement Docker in their Azure platform which is a development that could potentially make integration of Linux applications with Microsoft products easier than before. The growth of Docker and Linux containers shows no sign of slowing. New businesses continue to jump onto the bandwagon on a regular basis.