Move secrets module outside of nixops

1 files changed, 61 insertions, 0 deletions

diff --git a/modules/secrets.nix b/modules/secrets.nix
new file mode 100644
index 0000000..b282e56
--- /dev/null
+++ b/modules/secrets.nix
@@ -0,0 +1,61 @@
+{ lib, pkgs, config, ... }:
+{
+  options.secrets = {
+    keys = lib.mkOption {
+      type = lib.types.listOf lib.types.unspecified;
+      default = [];
+      description = "Keys to upload to server";
+    };
+    location = lib.mkOption {
+      type = lib.types.path;
+      default = "/var/secrets";
+      description = "Location where to put the keys";
+    };
+  };
+  config = let
+    location = config.secrets.location;
+    keys = config.secrets.keys;
+    empty = pkgs.runCommand "empty" { preferLocalBuild = true; } "mkdir -p $out && touch $out/done";
+    dumpKey = v: ''
+        mkdir -p secrets/$(dirname ${v.dest})
+        echo -n ${lib.strings.escapeShellArg v.text} > secrets/${v.dest}
+        cat >> mods <<EOF
+        ${v.user or "root"} ${v.group or "root"} ${v.permissions or "0600"} secrets/${v.dest}
+        EOF
+        '';
+    secrets = pkgs.runCommand "secrets.tar" {} ''
+      touch mods
+      tar --format=ustar --mtime='1970-01-01' -P --transform="s@${empty}@secrets@" -cf $out ${empty}/done
+      ${builtins.concatStringsSep "\n" (map dumpKey keys)}
+      cat mods | while read u g p k; do
+      tar --format=ustar --mtime='1970-01-01' --owner="$u" --group="$g" --mode="$p" --append -f $out "$k"
+      done
+      '';
+  in lib.mkIf (builtins.length keys > 0) {
+    system.activationScripts.secrets = {
+      deps = [ "users" "wrappers" ];
+      text = ''
+        install -m0750 -o root -g keys -d ${location}
+        if [ -f /run/keys/secrets.tar ]; then
+          if [ ! -f ${location}/currentSecrets ] || ! sha512sum -c --status "${location}/currentSecrets"; then
+            echo "rebuilding secrets"
+            rm -rf ${location}
+            install -m0750 -o root -g keys -d ${location}
+            ${pkgs.gnutar}/bin/tar --strip-components 1 -C ${location} -xf /run/keys/secrets.tar
+            sha512sum /run/keys/secrets.tar > ${location}/currentSecrets
+            find ${location} -type d -exec chown root:keys {} \; -exec chmod o-rx {} \;
+          fi
+        fi
+        '';
+    };
+    deployment.keys."secrets.tar" = {
+      permissions = "0400";
+      # keyFile below is not evaluated at build time by nixops, so the
+      # `secrets` path doesn’t necessarily exist when uploading the
+      # keys, and nixops is unhappy.
+      user = "root${builtins.substring 10000 1 secrets}";
+      group = "root";
+      keyFile = "${secrets}";
+    };
+  };
+}