pyrox.dev
1{ config, pkgs, modulesPath, ... }:
2
3# This attempts to pull a nix expression from this EC2 instance's user-data.
4
5let
6 bootScript = pkgs.writeScript "bootscript.sh" ''
7 #!${pkgs.stdenv.shell} -eux
8
9 echo "attempting to fetch configuration from user-data..."
10
11 export PATH=${config.nix.package}/bin:${pkgs.wget}/bin:${pkgs.systemd}/bin:${pkgs.gnugrep}/bin:${pkgs.gnused}/bin:${config.system.build.nixos-rebuild}/bin:$PATH
12 export NIX_PATH=/nix/var/nix/profiles/per-user/root/channels/nixos:nixos-config=/etc/nixos/configuration.nix:/nix/var/nix/profiles/per-user/root/channels
13
14 userData="$(mktemp)"
15 wget -q --wait=1 --tries=0 --retry-connrefused -O - http://169.254.169.254/2011-01-01/user-data > "$userData"
16
17 if [[ $? -eq 0 ]]; then
18 echo "user-data fetched"
19 # If the user-data looks like it could be a nix expression,
20 # copy it over. Also, look for a magic three-hash comment and set
21 # that as the channel.
22 if sed '/^\(#\|SSH_HOST_.*\)/d' < "$userData" | grep -q '\S'; then
23 channels="$(grep '^###' "$userData" | sed 's|###\s*||')"
24 printf "%s" "$channels" | while read channel; do
25 echo "writing channel: $channel"
26 done
27
28 if [[ -n "$channels" ]]; then
29 printf "%s" "$channels" > /root/.nix-channels
30 nix-channel --update
31 fi
32
33 echo "setting configuration"
34 cp "$userData" /etc/nixos/configuration.nix
35 else
36 echo "user-data does not appear to be a nix expression; ignoring"
37 fi
38 else
39 echo "failed to fetch user-data"
40 fi
41
42 type -f nixos-rebuild
43
44 nixos-rebuild switch
45 '';
46in {
47 imports = [ "${modulesPath}/virtualisation/amazon-image.nix" ];
48 boot.postBootCommands = ''
49 ${bootScript} &
50 '';
51}