Containers: what they give and when they're redundant
What problem it solves
Matching versions and dependencies across machines. Instead of installing and configuring on each server, you build one image and run it everywhere. Hence the ease of scaling: running another instance is a matter of seconds.
How to build a good image
A lean, up-to-date base, a multi-stage build so build tools don't reach the final image, a user without full permissions, and an explicit version tag — not just “latest.”
Don't put secrets in the image. They're injected at runtime.
When you don't need it
A static site, a small function, or a system running on a managed platform that handles this itself. Containers add a layer to maintain; if you don't get portability or uniformity from them, skip them.
Going deeper
Scan images for vulnerabilities in the build process, and rebuild on a regular cadence even without a code change — most vulnerabilities come from the base layer. And set a clear tagging policy so you can always say exactly which version is running now.