fix cryptsetup luksOpen idempotency, add luks-lvm test

default.nix

@@ -151,7 +151,7 @@ let
     recursiveUpdate
     (mount-f { device = "/dev/mapper/${x.name}"; } x.content)
     {luks.${q.device} = ''
-      cryptsetup luksOpen ${q.device} ${x.name} ${if builtins.hasAttr "keyfile" x then "--key-file " + x.keyfile else ""}
+      cryptsetup status ${x.name} >/dev/null 2>/dev/null || cryptsetup luksOpen ${q.device} ${x.name} ${if builtins.hasAttr "keyfile" x then "--key-file " + x.keyfile else ""}
     '';}
   );
 

example/luks-lvm.nix

@@ -0,0 +1,78 @@
+{
+  type = "devices";
+  content = {
+    vdb = {
+      type = "table";
+      format = "gpt";
+      partitions = [
+        {
+          type = "partition";
+          part-type = "ESP";
+          start = "1MiB";
+          end = "100MiB";
+          fs-type = "FAT32";
+          bootable = true;
+          content = {
+            type = "filesystem";
+            format = "vfat";
+            mountpoint = "/boot";
+            options = [
+              "defaults"
+            ];
+          };
+        }
+        {
+          type = "partition";
+          part-type = "primary";
+          start = "100MiB";
+          end = "100%";
+          content = {
+            type = "luks";
+            algo = "aes-xts...";
+            name = "crypted";
+            keyfile = "/tmp/secret.key";
+            extraArgs = [
+              "--hash sha512"
+              "--iter-time 5000"
+            ];
+            content = {
+              type = "lvm";
+              name = "pool";
+              lvs = {
+                root = {
+                  type = "lv";
+                  size = "100M";
+                  mountpoint = "/";
+                  content = {
+                    type = "filesystem";
+                    format = "ext4";
+                    mountpoint = "/";
+                    options = [
+                      "defaults"
+                    ];
+                  };
+                };
+                home = {
+                  type = "lv";
+                  size = "10M";
+                  content = {
+                    type = "filesystem";
+                    format = "ext4";
+                    mountpoint = "/home";
+                  };
+                };
+                raw = {
+                  type = "lv";
+                  size = "10M";
+                  content = {
+                    type = "noop";
+                  };
+                };
+              };
+            };
+          };
+        }
+      ];
+    };
+  };
+}

tests/luks-lvm.nix

@@ -0,0 +1,39 @@
+{ makeTest ? import <nixpkgs/nixos/tests/make-test-python.nix>
+, pkgs ? (import <nixpkgs> {})
+}:
+let
+  makeTest' = args:
+    makeTest args {
+      inherit pkgs;
+      inherit (pkgs) system;
+    };
+  disko-config = import ../example/luks-lvm.nix;
+  tsp-create = pkgs.writeScript "create" ((pkgs.callPackage ../. {}).create disko-config);
+  tsp-mount = pkgs.writeScript "mount" ((pkgs.callPackage ../. {}).mount disko-config);
+in makeTest' {
+  name = "disko";
+
+  nodes.machine =
+    { config, pkgs, modulesPath, ... }:
+
+    {
+      imports = [
+        (modulesPath + "/profiles/installation-device.nix")
+        (modulesPath + "/profiles/base.nix")
+      ];
+
+      # speed-up eval
+      documentation.enable = false;
+
+      virtualisation.emptyDiskImages = [ 512 ];
+    };
+
+  testScript = ''
+    machine.succeed("echo 'secret' > /tmp/secret.key");
+    machine.succeed("${tsp-create}");
+    machine.succeed("${tsp-mount}");
+    machine.succeed("${tsp-mount}"); # verify that the command is idempotent
+    machine.succeed("cryptsetup isLuks /dev/vdb2");
+    machine.succeed("grep -qs '/mnt/home' /proc/mounts");
+  '';
+}