The secret to fast Docker builds and secure images is knowing what NOT to include.
1Context is Everything
A smaller build context means faster transfers and less disk usage. For large projects, an optimized .dockerignore can save gigabytes of data transfer over time.
2The Security Layer
Your final image might be public on Docker Hub. If you forget to ignore .env, .git, or npm-debug.log, you might be exposing your server's deepest secrets to the world.
3Cache Efficiency
Ignoring temporary files and logs ensures that Docker's layer cache isn't invalidated by irrelevant file changes, keeping your rebuilds consistently fast.
