Docker Images, Layers & the Dockerfile
~12 min read
How a Dockerfile becomes a versioned, cacheable image, and why layer order matters for build speed.
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Key points
- •Each Dockerfile instruction creates a cacheable layer
- •Order instructions from least-frequently-changing to most-frequently-changing for faster builds
- •An image is immutable layers; a container adds one writable layer on top
- •Images are tagged (e.g. myapp:1.2.0) and pushed to a registry like ECR for orchestrators to pull