Which of the following is NOT a characteristic of Containers?

Containers are designed based on the principle of immutability. A container image is a static, unchangeable file that includes everything needed to run an application. This design ensures that containers are predictable and repeatable, behaving identically across different environments. They are also self-contained, packaging the application with all its dependencies. The concept of being "ever-changing" directly contradicts the core tenet of immutability, where updates are handled by replacing an existing container with a new one built from an updated image, rather than modifying a running container.

A. Predictable: This is incorrect because a primary benefit of containers is their predictable behavior, as they bundle dependencies, eliminating the "it works on my machine" problem.

B. Repeatable: This is incorrect because container images serve as templates, allowing for the consistent and repeatable creation of identical application instances.

D. Self-contained: This is incorrect because being self-contained is a defining feature; containers package an application and all its libraries and dependencies into a single, isolated unit.

1. Nokia White Paper: The move to cloud-native: A Nokia perspective for communication service providers. (2020). This document emphasizes key cloud-native characteristics. On page 4, it states, "Cloud-native applications are packaged as lightweight, self-contained containers..." and discusses the "immutable infrastructure" paradigm, which is the opposite of "ever-changing." The benefits of CI/CD pipelines, which rely on predictable and repeatable deployments, are also highlighted.

2. Nokia White Paper: Cloud native design for 5G Core. (2021). This paper describes the principles of cloud-native architecture, which heavily utilizes containers. Section 2, "Cloud native principles," discusses how applications are decomposed into "independent, self-contained and reusable microservices," which are then packaged into containers. This supports the self-contained, predictable, and repeatable nature required for scalable 5G networks.

3. University of California, Berkeley Courseware: CS 162: Operating Systems and System Programming, Lecture 19: Virtual Machines & Containers. The lecture notes describe containers (like Docker) as providing a "consistent, predictable environment" and being "self-contained." This directly confirms options A, B, and D as valid characteristics. The concept of building immutable images is central to this consistency. (Available through Berkeley EECS course materials).