Image
Immutable application package built from ordered Dockerfile layers.
DevOps module 03
Package once. Run consistently.
Learn how Docker turns application source into a portable, inspectable and versioned runtime artifact.
Container
Running process created from an image with isolated filesystem and networking.
Registry
Versioned image store used to distribute trusted artifacts.
Volume
Persistent data mounted outside the disposable container layer.
Network
Controlled communication path between containers and external services.
Security
Run as non-root, minimise packages, scan images and avoid embedded secrets.
Build checklist
Small base image
Use a supported minimal image and pin deliberate versions.
Layer efficiency
Copy dependency manifests before source to improve cache reuse.
Runtime safety
Use a non-root user, health checks and read-only configuration where practical.