If your Docker build takes 30+ seconds every time you change a single line of code, your Dockerfile is working against you. The secret to lightning-fast builds lies in mastering layer caching.
Here are the five core rules to optimize your Dockerfiles for maximum performance and predictability.
1. Order by Volatility (Least to Most)
When Docker builds an image, it caches the instructions as layers and reuses them if their content hash hasn't changed. However, if a single layer changes, all subsequent layers get rebuilt.
Because of this cascading effect, you must sort your instructions from the least volatile (changes rarely) to the most volatile (changes constantly).
