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Discussion on: A crash course on optimizing your Docker images for production

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vinayhegde1990 profile image
Vinay Hegde

Great article for people like me grappling the nuances of Docker, Adnan!

Quick question - Is the final code snippet you've shared (starting with FROM alpine AS builder) and ending with (CMD ["node", "app.js"]) part of the same Dockerfile?

If yes, won't that add more layers & thus increase overall size? Please correct me if I'm wrong.

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adnanrahic profile image
Adnan Rahić Author

On the contrary. It'll reduce the number of layers. The builder image is an intermediary image and will not be part of the final image. The bottom part of the Dockerfile is where you create a fresh image and copy over the node_modules. In doing so drastically reducing the number of layers, and excluding build dependencies.

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vinayhegde1990 profile image
Vinay Hegde

Thanks for the explanation that builder images are intermediate and not a part of the final one.

While I'll surely dabble with it myself for better clarity, from your experience so far - is this reduction possible for only Node apps or can be replicated for virtually any application?

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adnanrahic profile image
Adnan Rahić Author

It has nothing to do with the programming language or runtime. It solely has to do with the way you structure and build your images.