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 #!${pkgs.stdenv.shell} -eu
8
9 echo "attempting to fetch configuration from EC2 user data..."
10
11 export PATH=${config.nix.package}/bin:${pkgs.systemd}/bin:${pkgs.gnugrep}/bin:${pkgs.gnused}/bin:${config.system.build.nixos-rebuild}/bin:$PATH
12 export NIX_PATH=/nix/var/nix/profiles/per-user/root/channels/nixos:nixos-config=/etc/nixos/configuration.nix:/nix/var/nix/profiles/per-user/root/channels
13
14 userData=/etc/ec2-metadata/user-data
15
16 if [ -s "$userData" ]; then
17
18 # If the user-data looks like it could be a nix expression,
19 # copy it over. Also, look for a magic three-hash comment and set
20 # that as the channel.
21 if sed '/^\(#\|SSH_HOST_.*\)/d' < "$userData" | grep -q '\S'; then
22 channels="$(grep '^###' "$userData" | sed 's|###\s*||')"
23 printf "%s" "$channels" | while read channel; do
24 echo "writing channel: $channel"
25 done
26
27 if [[ -n "$channels" ]]; then
28 printf "%s" "$channels" > /root/.nix-channels
29 nix-channel --update
30 fi
31
32 echo "setting configuration from EC2 user data"
33 cp "$userData" /etc/nixos/configuration.nix
34 else
35 echo "user data does not appear to be a Nix expression; ignoring"
36 exit
37 fi
38 else
39 echo "no user data is available"
40 exit
41 fi
42
43 nixos-rebuild switch
44 '';
45in {
46 boot.postBootCommands = ''
47 ${bootScript} &
48 '';
49}