Container basics

What is a "Container"?

Containers are lightweight environments that bundle applications and their dependencies, enabling consistent performance across various environments. A well-constructed containerized application solves compatibility issues by packaging the code, libraries, and dependencies together, ensuring smooth deployment from development to production. 

Key Concepts: 

• Segregation: Containers operate independently on the same host, keeping applications and their resources separate. This prevents interference and enhances efficiency in shared environments. However, because containers share the same Linux kernel, this segregation may introduce security challenges that require additional attention. 

• Efficiency: Containers differ from traditional VMs by sharing the host system’s OS kernel. This design reduces overhead, leading to faster start times and lower resource consumption. While this provides significant efficiency, it also introduces potential security risks that will be addressed later in this document. 

• Portability: Containers are self-contained, meaning they can run on any system that supports container runtimes. While Docker remains a widely recognized runtime, Kubernetes production systems primarily utilize containerd and CRI-O, which conform to the Container Runtime Interface (CRI) standards. 

The predictable nature of containers makes them essential in agile development, especially within DevOps and CI/CD pipelines. Tools like Docker allow developers to replicate environments, enabling easy transitions across different stages of development. This portability and consistency in environment settings help teams innovate faster and streamline their workflows, making containerization an essential component of modern software development and deployment practices. 

Another important term to know is Container Images: