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# nixos-images
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Automatically weekly updated images for NixOS. This project is intended to extend the images created by hydra.nixos.org.
We are currently creating the images listed below:
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## Netboot images
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You can boot the netboot image using this [ipxe script ](https://github.com/nix-community/nixos-images/releases/download/nixos-unstable/netboot-x86_64-linux.ipxe ).
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It consists of the [kernel image ](https://github.com/nix-community/nixos-images/releases/download/nixos-unstable/bzImage-x86_64-linux ) and [initrd ](https://github.com/nix-community/nixos-images/releases/download/nixos-unstable/initrd-x86_64-linux ).
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## Kexec tarballs
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These images are used for unattended remote installation in [nixos-anywhere ](https://github.com/numtide/nixos-anywhere ).
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Kexec is a mechanism in Linux to load a new kernel from a running Linux to
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replace the current kernel. This is useful for booting the Nixos installer from
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existing Linux distributions, such as server provider that do not offer a NixOS
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option. After running kexec, the NixOS installer exists only in memory. At the
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time of writing, this requires at least 1.5GB of physical RAM (swap does not
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count) in the system. If not enough RAM is available, the initrd cannot be
loaded. Because the NixOS runs only in RAM, users can reformat all the system's
discs to prepare for a new NixOS installation.
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It can be booted as follows by running these commands as root:
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```
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curl -L https://github.com/nix-community/nixos-images/releases/download/nixos-unstable/nixos-kexec-installer-noninteractive-x86_64-linux.tar.gz | tar -xzf- -C /root
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/root/kexec/run
```
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The kexec installer comes with the following features:
- Re-uses ssh host keys from the sshd to not break `.ssh/known_hosts`
- Authorized ssh keys are read from `/root/.ssh/authorized_keys` , `/root/.ssh/authorized_keys2` and `/etc/ssh/authorized_keys.d/root`
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- Static ip addresses and routes are restored after reboot.
Interface that had dynamic addresses before are configured with DHCP and
to accept prefixes from ipv6 router advertisement
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The actual kexec happens with a slight delay (6s). This allows for easier
integration into automated nixos installation scripts, since you can cleanly
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disconnect from the running machine before the kexec takes place. The tarball
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is also designed to be run from NixOS, which can be useful for new installations
