Container Image Myths | Stop believing. Start understanding.

Container Image Myths

Container images are a foundational part of cloud-native platforms, yet they are often treated as simple build artifacts rather than security-critical, immutable components. This section breaks down common Container Image myths related to immutability, tagging, image size, caching, vulnerability scanning, and runtime behavior, using real-world scenarios to separate assumptions from reality. The goal is to clarify how container images are built, distributed, and consumed in Kubernetes so teams can design safer, more reliable, and more predictable delivery pipelines.

📄️ Myth: Container images truly support “build once, deploy anywhere"

This statement is frequently repeated in container and DevOps communities. Many engineers confidently claim that once a container image is built, it can run on any machine or Kubernetes cluster, regardless of the underlying hardware.During discussions with developers and SREs, this belief appears almost universally accepted.

📄️ Myth: A Container Image Digest Uniquely Identifies One Image

When discussing container images, the term digest is often used without qualification:

📄️ Myth: Dockerfile COPY preserves file ownership and permissions from the host

While running containers as a non-root user, I noticed something odd.