Remove node_modules from the final image

[shouichi]

No description provided.

[byroot]

I think not including the source is a good practice, but the RUN here is in its own layer, so this making the image any smaller.

[shouichi]

Thank you for the review. If I'm not mistaken, it does reduce the image size of the final image. Because node_modules is removed from the build image and node_module is prevented from copying (in COPY --from=build /rails /rails) in the final image.

[byroot]

Ah sorry, I missed that. Yeah, then the more logical thing would be to use --exclude flag in COPY, but it's relatively recent and might not be supported everywhere, so I guess it's OK.