Software Development Lifecycle (SDLC) evolved from waterfall software delivery to agile using modern DevOps and DevSecOps processes. Modern software applications are developed as encapsulated packages including application code, software dependencies, and runtime environment. This encapsulated is done using containerization technologies, and the most used in industry is Docker.

What is containerization?

Containerization technology is used for the development and delivery of modern applications. Both small and enterprise softwares using container technologies like Docker. Traditionally applications were developed using water methodologies where application requirements were created, applications were developed by developers, and the operations teams were responsible for deploying them in on-premises environments. The time it took to get the applications in front of customers was in months, and there was no guarantee of delivering a reliable software.

Then virtualization came, where the organizations can use on hardware and create multiple virtual machines for distributing load across the same infrastructure to save operational costs. In this case, applications are deployed manually using scripts and custom provisioning on VMs.

After virtualization, the modern way of delivering applications are cloud-native applications while organizations follow agile workflows and delivering software release on several times a day instead of months. The reliability of software in increased drastically and using application encapsulation using Docker, developers can deliver code faster without the problem of "works on your my machine".

Security also became important in DevOps software delivery so tools in Static Code Analysis play a crucial role in shipping secure code in staging and production environments.

What is Docker?

Docker is a company behind open source containerization technology names Docker. Built using Golang, an open-source programming language by Google. Docker helps build, release and run containerized applications anywhere, in dev, staging, and production, without requiring to create different environment configurations.

Docker is evolved after the virtualization technology. It runs on different operation systems, MacOS, Linux and Windows. Developers install Docker Desktop on their local development environments and using Dockerfile and version control systems like Git to development, test build applications. Applications run inside docker containers using the image created using the Dockerfile. Dockerfile containers instructions containing a lightweight base image and application configurations, these are called as layers. For small sizes of images, it is recommended to use minimal OS base image. Once docker image is created, we can run the container using the image.

Here are the following commands you need to build image and run container out of it: