proposal: use eatmydata for faster installations

[devkral]

what

apt uses syncs a lot. This slows down the installation of packages.

The main advantage safer updates are not relevant for docker as everything is thrown away whenever an error occurs.

Proposal

use eatmydata in images. This speeds up the installation/updates of packages dramatically.

[tianon]

This is a very interesting idea -- I think it would make a lot of sense for most Docker images to have APT use eatmydata, but unfortunately I don't think it's entirely a reasonable default for every use of the Docker images. 😬 🙈

[devkral]

Luckily this is no problem because eatmydata has two modes of operation:

• one which replaces the default call of apt/apt-get via symlink (the real program can be still used without using eatmydata by accessing it via the full path)
• and one where you have to specify it manually (default):
  eatmydata apt ....

This means we can have an opt-out/opt-in mechanism.
It would be enough to preinstall it (opt-in).

With eatmydata preinstalled (and documented) there are multiple advantages:

1. Internal bootstrapping usage for different docker image flavors. This saves time and current.
2. derivated images could use it out of the box.

• less space usage (no need to install it in the first step, often a build layer)
• much faster docker-builds on weaker PCs possible

3. Can be also used for other heavy syncing software