Optimising the disk footprint of GNU/Linux distributions for the Cloud (2013) | Hacker News Reader

Optimising the disk footprint of GNU/Linux distributions for the Cloud (2013)

dicosmo.org

25 pointsedwintorok7 comments

paper: http://hal.inria.fr/docs/00/67/43/79/PDF/paper.pdf

basically the idea here is that you can select on attributes like "fewest packages installed" or "smallest installed size" or "fewest changes to existing system" of the resulting set rather than just picking the first solution that satisfies the dependency tree.

I don't know how useful this is, given that (from the perspective of a package maintainer) most code is written to use one specific library; iow, there are few || dependencies in the tree, even for Gentoo, which supports almost every configuration that upstream does. other distros will have significantly fewer, given that their binaries will, by the nature of Linux linking, be linked to a single set of libraries (assuming no dlopen).

Note that not all packages are created equal. The vast majority of base packages are a few kilobytes each. The space on a minimal system (e.g. Ubuntu core) is by far taken up by just a few packages: locales, charmaps, and tzdata. (You might also count the kernel, initramfs, etc. if you’re trying to create something like a Docker base-image.)

Speaking of Docker base-images, I really wish Emdebian Baked (http://www.emdebian.org/baked/index.html) was still an active project. There’s no reason “finalized” read-only cloud images should have apt installed at all—and therefore no need for any of apt’s dependencies (of which there are shockingly many), or any of the metadata each package comes with to appease apt.

To avoid all the locales and stuff, use Musl libc. Alpine Linux is an option that supports it.

Redhat's Project Atomic can bake in RPMs using ostree.

Alpine Linux might be helpful for minimizing both RAM and disk footprint.

The idea that you need 154 packages to run Apache is pretty sad. Part of it is base system bloat, the rest is tge idea you better link packages with all their possible options (unless you use gentoo).

The multistrap script at https://gist.github.com/anonymous/50dfdfe99438e53c8e58 produces a 425mb Debian system including vim, Linux kernel, Apache, perl and Ruby. After bzip2 that's 115mb, which is about a second's worth of GigE.

But that's assuming you even need to transfer or copy the base image, which in a healthy setup it should be possible to avoid -- the majority of Linux distributions bundle very similar content, and amongst virtual machines of the same distribution, the base systems are almost identical. It wouldn't be difficult to create a differential transfer protocol and/or virtualized block device for this specific use case that minimized copies and transfers.

There is plenty of open source tech for this already. For example with LVM2 thin provisioning it's possible to clone and resize a VM image from 2GB to 40GB, ready for boot in under 2 seconds.. https://gist.github.com/anonymous/fdcbcc27278c287ce5e0

Anyone can conver this article to a "apt-get install thinner" command?

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