{ config, pkgs, modulesPath, ... }: # This attempts to pull a nix expression from this EC2 instance's user-data. let bootScript = pkgs.writeScript "bootscript.sh" '' #!${pkgs.stdenv.shell} -eux echo "attempting to fetch configuration from user-data..." export PATH=${config.nix.package}/bin:${pkgs.wget}/bin:${pkgs.systemd}/bin:${pkgs.gnugrep}/bin:${pkgs.gnused}/bin:${config.system.build.nixos-rebuild}/bin:$PATH 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 userData="$(mktemp)" wget -q --wait=1 --tries=0 --retry-connrefused -O - http://169.254.169.254/2011-01-01/user-data > "$userData" if [[ $? -eq 0 ]]; then echo "user-data fetched" # If the user-data looks like it could be a nix expression, # copy it over. Also, look for a magic three-hash comment and set # that as the channel. if sed '/^\(#\|SSH_HOST_.*\)/d' < "$userData" | grep -q '\S'; then channels="$(grep '^###' "$userData" | sed 's|###\s*||')" printf "%s" "$channels" | while read channel; do echo "writing channel: $channel" done if [[ -n "$channels" ]]; then printf "%s" "$channels" > /root/.nix-channels nix-channel --update fi echo "setting configuration" cp "$userData" /etc/nixos/configuration.nix else echo "user-data does not appear to be a nix expression; ignoring" fi else echo "failed to fetch user-data" fi type -f nixos-rebuild nixos-rebuild switch ''; in { boot.postBootCommands = '' ${bootScript} & ''; }