And those lightweight VM base images are possible because Docker applied a downward pressure on OS base image sizes! Alpine Linux doesn't get enough credit for this; in addition to being a great base image, it was also the first distro to prioritise fast and small image creation (Gentoo and Arch were small, but not fast to create).

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kgwgk 3 hours ago | parent [-]

Maybe in that alternative future of massive block devices some downward pressure on image sizes would have been applied just the same.

	▲	avsm 3 hours ago \| parent [-]
		It's not as easy; a block device has to be bootable and so usually bundles a kernel (large). And because the filesystem inside is opaque, you can't do layering like Docker does easily via overlayfs and friends. libguestfs does a heroic job of making VM images easier to manipulate from code, but it's an uphill battle...