Mastering Cloud‑Native Container Design: 8 Essential Principles

Introduction

This article is based on Red Hat consultant Bilgin Ibryam’s whitepaper “Principles of Container‑Based Application Design”, which has been republished on the Kubernetes website. The original whitepaper can be downloaded from Red Hat’s site.

Classic Software Design Principles

KISS – Keep It Simple, Stupid

DRY – Don’t Repeat Yourself

YAGNI – You Aren’t Gonna Need It

SoC – Separation of Concerns

SOLID – Single Responsibility, Open‑Closed, Liskov Substitution, Interface Segregation, Dependency Inversion

Red Hat adds a set of cloud‑native container design principles:

Single‑Concern Principle (SCP)

High Observability Principle (HOP)

Life‑Cycle Conformance Principle (LCP)

Image Immaturity Principle (IIP)

Process Disposability Principle (PDP)

Self‑Containment Principle (S‑CP)

Runtime Confinement Principle (RCP)

Single‑Concern Principle (SCP)

The SCP is similar to the SOLID SRP but focuses on a container’s responsibility rather than a class’s. A container should solve one problem well, making its image reusable across applications. Typically a container runs a single process that addresses a single concern.

If a microservice needs to handle multiple concerns, use sidecar or init‑container patterns to keep each container focused on a single task.

High Observability Principle (HOP)

Containers must expose APIs that allow the platform to observe health and behavior, enabling automated updates and lifecycle management. Applications should emit logs to STDOUT/STDERR and expose metrics and tracing data (e.g., Prometheus, OpenTracing) for aggregation tools.

Life‑Cycle Conformance Principle (LCP)

LCP requires containers to consume platform events and react appropriately, such as handling SIGTERM for graceful shutdown, or using PreStop and PostStart hooks for initialization and cleanup.

Image Immaturity Principle (IIP)

Once built, a container image must be immutable across environments. Any change requires building a new image, enabling reliable roll‑backs and forward‑rolls.

Process Disposability Principle (PDP)

Containers should be short‑lived and replaceable at any time, supporting rapid start‑up and shutdown, and allowing the platform to reschedule them on different hosts.

Self‑Containment Principle (S‑CP)

A container must include everything it needs to run, relying only on the Linux kernel and any additional libraries, runtimes, or dependencies packaged at build time. Configuration that varies per environment should be supplied at runtime (e.g., via ConfigMaps).

Runtime Confinement Principle (RCP)

Containers must declare their resource requirements (CPU, memory, network, disk) so the platform can schedule, auto‑scale, and enforce limits, preventing termination due to resource exhaustion.

Conclusion

Cloud‑native is both a destination and a way of working. Following these principles helps you become a good cloud‑native citizen.

Additional Best Practices

Keep images as small as possible by removing temporary files and unnecessary packages.

Support arbitrary user IDs; avoid requiring a specific user.

Expose important ports with the EXPOSE instruction.

Use volumes for persistent data.

Add metadata (labels, annotations) to images.

Synchronize host and image time/ID when needed.