1 files changed, 74 insertions, 2 deletions
diff --git a/krebs/4lib/infest/prepare.sh b/krebs/4lib/infest/prepare.sh
index 0bfc49380..b3824c7d4 100644
--- a/krebs/4lib/infest/prepare.sh
+++ b/krebs/4lib/infest/prepare.sh
@@ -1,6 +1,9 @@
 #! /bin/sh
 set -efu
 
+nix_url=https://nixos.org/releases/nix/nix-1.10/nix-1.10-x86_64-linux.tar.bz2
+nix_sha256=504f7a3a85fceffb8766ae5e1005de9e02e489742f5a63cc3e7552120b138bf4
+
 prepare() {(
   if test -e /etc/os-release; then
     . /etc/os-release
@@ -33,6 +36,13 @@ prepare() {(
             ;;
         esac
         ;;
+      nixos)
+        case $(cat /proc/cmdline) in
+          *' root=LABEL=NIXOS_ISO '*)
+            prepare_nixos_iso "$@"
+            exit
+        esac
+        ;;
     esac
   elif test -e /etc/centos-release; then
     case $(cat /etc/centos-release) in
@@ -70,7 +80,25 @@ prepare_debian() {
   prepare_common
 }
 
-prepare_common() {
+prepare_nixos_iso() {
+  mountpoint /mnt
+
+  type git 2>/dev/null || nix-env -iA nixos.git
+
+  mkdir -p /mnt/"$target_path"
+  mkdir -p "$target_path"
+
+  if ! mountpoint "$target_path"; then
+    mount --rbind /mnt/"$target_path" "$target_path"
+  fi
+
+  mkdir -p bin
+  rm -f bin/nixos-install
+  cp "$(type -p nixos-install)" bin/nixos-install
+  sed -i "s@^NIX_PATH=\"[^\"]*\"@NIX_PATH=$target_path@" bin/nixos-install
+}
+
+prepare_common() {(
 
   if ! getent group nixbld >/dev/null; then
     groupadd -g 30000 -r nixbld
@@ -133,6 +161,50 @@ prepare_common() {
     mkdir -p /mnt/nix
     mount --bind /nix /mnt/nix
   fi
-}
+
+  #
+  # install nix
+  #
+
+  # install nix on host (cf. https://nixos.org/nix/install)
+  if ! test -e /root/.nix-profile/etc/profile.d/nix.sh; then
+    (
+      verify() {
+        printf '%s  %s\n' $nix_sha256  $(basename $nix_url) | sha256sum -c
+      }
+      if ! verify; then
+        curl -C - -O "$nix_url"
+        verify
+      fi
+    )
+    nix_src_dir=$(basename $nix_url .tar.bz2)
+    tar jxf $nix_src_dir.tar.bz2
+    $nix_src_dir/install
+  fi
+
+  . /root/.nix-profile/etc/profile.d/nix.sh
+
+  for i in \
+    bash \
+    coreutils \
+    # This line intentionally left blank.
+  do
+    if ! nix-env -q $i | grep -q .; then
+      nix-env -iA nixpkgs.pkgs.$i
+    fi
+  done
+
+  # install nixos-install
+  if ! type nixos-install 2>/dev/null; then
+    nixpkgs_expr='import <nixpkgs> { system = builtins.currentSystem; }'
+    nixpkgs_path=$(find /nix/store -mindepth 1 -maxdepth 1 -name *-nixpkgs-* -type d)
+    nix-env \
+      --arg config "{ nix.package = ($nixpkgs_expr).nix; }" \
+      --arg pkgs "$nixpkgs_expr" \
+      --arg modulesPath 'throw "no modulesPath"' \
+      -f $nixpkgs_path/nixpkgs/nixos/modules/installer/tools/tools.nix \
+      -iA config.system.build.nixos-install
+  fi
+)}
 
 prepare "$@"