nixos/overlayfs: add test

nixos/tests/all-tests.nix

@@ -172,6 +172,7 @@ in
   osquery = handleTest ./osquery.nix {};
   osrm-backend = handleTest ./osrm-backend.nix {};
   ostree = handleTest ./ostree.nix {};
+  overlayfs = handleTest ./overlayfs.nix {};
   pam-oath-login = handleTest ./pam-oath-login.nix {};
   pam-u2f = handleTest ./pam-u2f.nix {};
   pantheon = handleTest ./pantheon.nix {};

nixos/tests/overlayfs.nix

@@ -0,0 +1,57 @@
+import ./make-test.nix ({ pkgs, ... }: {
+  name = "overlayfs";
+  meta.maintainers = with pkgs.stdenv.lib.maintainers; [ bachp ];
+
+  machine = { pkgs, ... }: {
+    virtualisation.emptyDiskImages = [ 512 ];
+    networking.hostId = "deadbeef";
+    environment.systemPackages = with pkgs; [ parted ];
+  };
+
+  testScript = ''
+    $machine->succeed("ls /dev");
+
+    $machine->succeed("mkdir -p /tmp/mnt");
+
+    # Test ext4 + overlayfs
+    $machine->succeed(
+
+      "mkfs.ext4 -F -L overlay-ext4 /dev/vdb",
+      "mount -t ext4 /dev/vdb /tmp/mnt",
+
+      "mkdir -p /tmp/mnt/upper /tmp/mnt/lower /tmp/mnt/work /tmp/mnt/merged",
+
+      # Setup some existing files
+      "echo 'Replace' > /tmp/mnt/lower/replace.txt",
+      "echo 'Append' > /tmp/mnt/lower/append.txt",
+      "echo 'Overwrite' > /tmp/mnt/lower/overwrite.txt",
+
+      "mount -t overlay overlay -o lowerdir=/tmp/mnt/lower,upperdir=/tmp/mnt/upper,workdir=/tmp/mnt/work /tmp/mnt/merged",
+
+      # Test new
+      "echo 'New' > /tmp/mnt/merged/new.txt",
+      "[[ \"\$(cat /tmp/mnt/merged/new.txt)\" == \"New\" ]]",
+
+      # Test replace
+      "[[ \"\$(cat /tmp/mnt/merged/replace.txt)\" == \"Replace\" ]]",
+      "echo 'Replaced' > /tmp/mnt/merged/replace-tmp.txt",
+      "mv /tmp/mnt/merged/replace-tmp.txt /tmp/mnt/merged/replace.txt",
+      "[[ \"\$(cat /tmp/mnt/merged/replace.txt)\" == \"Replaced\" ]]",
+
+      # Overwrite
+      "[[ \"\$(cat /tmp/mnt/merged/overwrite.txt)\" == \"Overwrite\" ]]",
+      "echo 'Overwritten' > /tmp/mnt/merged/overwrite.txt",
+      "[[ \"\$(cat /tmp/mnt/merged/overwrite.txt)\" == \"Overwritten\" ]]",
+
+      # Test append
+      "[[ \"\$(cat /tmp/mnt/merged/append.txt)\" == \"Append\" ]]",
+      "echo 'ed' >> /tmp/mnt/merged/append.txt",
+      #"cat /tmp/mnt/merged/append.txt && exit 1",
+      "[[ \"\$(cat /tmp/mnt/merged/append.txt)\" == \"Append\ned\" ]]",
+
+      "umount /tmp/mnt/merged",
+      "umount /tmp/mnt",
+      "udevadm settle"
+    );
+  '';
+})