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weberc2
Asked: 2021-10-27 17:39:13 +0800 CST

How to do a fresh install on every boot

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I want my servers to come up cleanly on each boot rather than having state which persists across boots. Short of PXE-booting, is there any way to do this? In particular, I’m curious if live-CDs do something similar (writes don’t persist—perhaps they use an in-memory filesystem)?

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2 Answers

  1. "I’m curious if live-CDs do something similar"

    Yes that's exactly what they do. The live session is loaded into RAM and changes do not persist after a reboot.

    You can accomplish what you are asking with a liveCD, but you can also use a USB flash drive with installation media. Just choose the "Try Ubuntu" option.

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  2. Here's something I have used in the past: The overlayroot package in the Ubuntu repositories.

    Description: use an overlayfs on top of a read-only root filesystem This package adds functionality to an initramfs built by initramfs-tools. When installed and configured, the initramfs will mount an overlayfs filesystem on top of a read-only root volume. . The changes can be written to a in-memory temporary filesystem, a filesystem on an existing block device, or a dmcrypt encrypted block device.

    In other words,

    • The booted system (/) is read-only, like a LiveUSB's "Try Ubuntu" environment. Changes can be made, but those changes are on the overlayfs, and do not persist across a reboot.

    • For editable data, store the data on a different partition. A different partition can be mounted read/write, so those changes do persist across reboots.

    • When time comes to tweak or update the system, a GRUB command will mount the system read-write. You set up your system exactly way you want it to boot every time, then just turn overlayroot back on and reboot.

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