Add filesystem option to automatically grow to the maximum size

This is primarily for EC2 and other cloud environments, where the disk
may be bigger than the original image.

2 files changed, 37 insertions, 1 deletions

diff --git a/nixos/tests/make-test.nix b/nixos/tests/make-test.nix
index 285ca5b71d6e..f3e26aa7e74d 100644
--- a/nixos/tests/make-test.nix
+++ b/nixos/tests/make-test.nix
@@ -2,4 +2,4 @@ f: { system ? builtins.currentSystem, ... } @ args:
 
 with import ../lib/testing.nix { inherit system; };
 
-makeTest (if builtins.isFunction f then f (args // { inherit pkgs; }) else f)
+makeTest (if builtins.isFunction f then f (args // { inherit pkgs; inherit (pkgs) lib; }) else f)
diff --git a/nixos/tests/resize-root.nix b/nixos/tests/resize-root.nix
new file mode 100644
index 000000000000..c8ccab38ab6f
--- /dev/null
+++ b/nixos/tests/resize-root.nix
@@ -0,0 +1,36 @@
+import ./make-test.nix ({ pkgs, lib, ...} : {
+
+  meta.maintainers = [ lib.maintainers.eelco ];
+
+  machine = { config, pkgs, ... }: {
+    virtualisation.diskSize = 512;
+    fileSystems = lib.mkVMOverride {
+      "/".autoResize = true;
+    };
+  };
+
+  testScript =
+    ''
+      # Create a VM with a 512 MiB disk.
+      $machine->start;
+      $machine->waitForUnit("multi-user.target");
+      my $blocks = $machine->succeed("stat -c %b -f /");
+      my $bsize = $machine->succeed("stat -c %S -f /");
+      my $size = $blocks * $bsize;
+      die "wrong free space $size" if $size < 480 * 1024 * 1024 || $size > 512 * 1024 * 1024;
+      $machine->succeed("touch /marker");
+      $machine->shutdown;
+
+      # Grow the disk to 1024 MiB.
+      system("qemu-img resize vm-state-machine/machine.qcow2 1024M") == 0 or die;
+
+      # Start the VM again and check whether the initrd has correctly
+      # grown the root filesystem.
+      $machine->start;
+      $machine->waitForUnit("multi-user.target");
+      $machine->succeed("[ -e /marker ]");
+      my $blocks = $machine->succeed("stat -c %b -f /");
+      my $size = $blocks * $bsize;
+      die "wrong free space $size" if $size < 980 * 1024 * 1024 || $size > 1024 * 1024 * 1024;
+    '';
+})