Answer
COPY/ADD track file checksums; any change invalidates following layers, causing rebuild.
Quick Answer
Docker layer caching is based on the content of the instruction and what was copied at that point. If you change any file that COPY or ADD includes, the hash of that instruction changes, invalidating that layer's cache and every layer after it. Even a timestamp change in a copied file busts the cache for the rest of the build.
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ