Answer
Lower layers cannot be changed without invalidating upper layers; ordering helps maximize caching.
Quick Answer
Each instruction in a Dockerfile creates a cached layer. If an early layer changes (like COPY package.json), all subsequent layers are invalidated and rebuilt. Put slow, rarely-changing steps (install OS packages) early; put fast, frequently-changing steps (copy your code) late. This keeps rebuilds fast during development.
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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