Preparation
Build NixOS kexec package
# new cmd: nix-build '<nixpkgs/nixos>' -A config.system.build.kexec_tarball -I nixos-config=./configuration.nix -Q -j 4
{ lib, pkgs, config, ... }:
with lib;
{
imports = [ <nixpkgs/nixos/modules/installer/netboot/netboot-minimal.nix> ./kexec.nix ./justdoit.nix ];
#boot.supportedFilesystems = [ "zfs" ];
boot.loader.grub.enable = false;
boot.kernelParams = [
"console=ttyS0,115200" # allows certain forms of remote access, if the hardware is setup right
"panic=30" "boot.panic_on_fail" # reboot the machine upon fatal boot issues
];
systemd.services.sshd.wantedBy = mkForce [ "multi-user.target" ];
networking.hostName = "kexec";
# example way to embed an ssh pubkey into the tar
users.users.root.openssh.authorizedKeys.keys = [ "ssh-rsa AAAAB3.... Your-SSH-key" ];
}
- Build kexec package like shown at the beginning of the file:
nix-build '<nixpkgs/nixos>' -A config.system.build.kexec_tarball -I nixos-config=./configuration.nix -Q -j 4
Create Scaleway Instance
- Open Scaleway "Create a server" page
- Enter name
- Select region
- Select server type
- This will only work for the V and X types of servers (e.g. VC1M or X64-15GB)
- I selected a VC1M for the rest of this guide
- Select "Debian Sid" from the distributions tab
- At the time of writing of this guide the Ubuntu Xenial did not have a kexec enabled kernel
- create server
- wait until server has been provisioned and is done booting
- Can be checked by looking at the console
Start NixOS kexec system
- copy the results of the nix-build to the server
scp result/tarball/nixos-system-x86_64-linux.tar.xz root@51.YY.XX.93:
- ssh into the server
- extract the tarball into /
cd /
tar -xf /root/nixos-system-x86_64-linux.tar.xz
- execute the kexec_nixos script
./kexec_nixos
- You should see output like this:
root@scalenix:/# ./kexec_nixos
++ mktemp -d
+ cd /tmp/tmp.iDXuzu8Ec4
+ pwd
/tmp/tmp.iDXuzu8Ec4
+ mkdir initrd
+ pushd initrd
/tmp/tmp.iDXuzu8Ec4/initrd /tmp/tmp.iDXuzu8Ec4
+ cat /ssh_pubkey
cat: /ssh_pubkey: No such file or directory
+ find -type f
+ cpio -o -H newc
+ gzip -9
1 block
+ popd
/tmp/tmp.iDXuzu8Ec4
+ cat /nix/store/2lmw78k2ralvpn6fa270b53nz1xgqk8b-image/initrd extra.gz
+ kexec -l /nix/store/2lmw78k2ralvpn6fa270b53nz1xgqk8b-image/kernel --initrd=final.gz '--append=init=/nix/store/sv9hndbkrdxr1psi2jr82hkm1ba0j8bx-nixos-system-kexec-17.09.git.f3841ab/init loglevel=4 console=ttyS0,115200 panic=30 boot.panic_on_fail'
+ sync
+ echo 'executing kernel, filesystems will be improperly umounted'
executing kernel, filesystems will be improperly umounted
+ kexec -e
packet_write_wait: Connection to 51.15.71.93 port 22: Broken pipe
- Once the ssh connection is broken take a look at the servers console in the webinterface
