Docker tutorial is designed for the developers and those who are interested in learning Docker as a container service. This is the explanation of a newly aged Software Containerization Technology.
What is Docker?
Docker is a new technology for the Software Containerization in the field of IT. This is a container service designed as open source project that facilitates deployment of applications inside the software containers.
What is Container?
A Container is a standardized unit of software that makes packages of code and all its dependencies for the development, deployment, and shipment of the applications. Using Container the applications run quickly and reliably from one computing environment to another.
A Brief History of Docker
On March 20, 2013, a platform/service company named by dotCloud released an open source project known as Docker that relies on Linux Kernel Features such as namespaces and cgroups, to ensure resource isolation and to package an application along with its dependencies. In June 2014, the first version(Docker 1.0) was released as milestone signifying a level of quality, feature completeness, backward compatibility, and API stability to meet enterprise IT standards. Since then Docker has gain popularity and its usage has spread like wildfire in the software industry.
Uses of Docker
Using Docker, any Developer or system Admin can easily deploy the applications in a container as it provides an additional layer of abstraction and automation of OS-level Virtualization on Linux. In the simple form of words, this is a platform to build applications, package them along with their dependencies into a container and then these containers can be easily shipped to run on other machines.
Features of Docker
- A user can easily build, ship, and run its applications.
- All containers run by a single operating system kernel.
- Docker container is more light-weight than the virtual machines.
- A user can deploy Docker containers anywhere, on any physical and virtual machines and even on the cloud.
Components of Docker
Docker Container: It is a software package runs on Docker engine that is derived from “images” (created by combining and modifying standard images downloaded from public repositories by specifying their precise contents) specifying their precise contents.
Docker Engine: This is a Client-Server application installed on the host machine. This engine is the core component of Docker system.
Docker Hub: This is the Docker registry used to host various Docker images.
Docker Compose: This component is used to define applications using multiple Docker containers.
Docker for Windows: This allows a user to run Docker containers on Windows OS.
Docker for Linux: This allows a user to run Docker containers on the Linux OS.
Docker for Mac: This allows a user to run Docker containers on the Mac OS.
Advantages of Docker
Return on Investment and Cost Savings: ROI (Return on Investment) is the first advantage of using Dockers it is the biggest driver of most management decisions while selecting a new product. More a solution can drive down costs the better a solution it is. And in this way, Docker facilitates this saving by reducing infrastructure resources dramatically.
Standardization and Productivity: Standardization is the biggest advantage to a Docker-based architecture. It provides consistency across multiple developments and ensures repeatable development, builds, test, and production environments.
It allows a user to commit changes to the Docker images by containers. In case of upgrading any component, if there is a loss to the whole environment, then Docker container makes it easy to roll back the previous version of your Docker images by testing in a few minutes. It replicates quickly and achieves redundancy in a fast manner.
Rapid deployment: Docker reduces deployment in seconds via containers for every process and does not boot on OS. Deployment becomes easy as data can be created and destroyed without worrying.
Sharing: User can share its own containers by using a distant repository. For this sharing purpose, Red Hat provides a registry and also enables configuration for an individual repository.
Light and Minimal Overhead: Docker facilitates light and minimal overhead in a way of typically very small Docker images that reduces the deployment time of new application containers and enhance their rapid delivery.
Security: For security concerns, Docker provides a secure environment to run all the applications being isolated from each other thus having complete control over traffic flow and management.
Disadvantages of Docker
Missing Features: Docker is lack of many features like container self-registration, self-inspects, copying files from the host to the container, etc.
Complicated Data Storage: The data storage becomes complicated in using Docker as by design, all of the data inside a container leaves for a very long time when a container goes down that needs further a backup and recovery strategy.
Cross-Platform Compatibility: If an application is designed to run on Docker engine on Windows platform then it can’t run on Linux or vice-versa and this led to the limitation thus makes Docker less attractive in some highly heterogeneous environments which are composed of both Windows and Linux servers.
Split Container Ecosystem: Some container products don’t work with other ones because of the core platform of Docker as defined open-source.