1 files changed, 90 insertions, 0 deletions
diff --git a/nixos/tests/containers-tmpfs.nix b/nixos/tests/containers-tmpfs.nix
new file mode 100644
index 00000000000..d95178d1ff5
--- /dev/null
+++ b/nixos/tests/containers-tmpfs.nix
@@ -0,0 +1,90 @@
+import ./make-test-python.nix ({ pkgs, lib, ... }: {
+  name = "containers-tmpfs";
+  meta = {
+    maintainers = with lib.maintainers; [ patryk27 ];
+  };
+
+  machine =
+    { pkgs, ... }:
+    { imports = [ ../modules/installer/cd-dvd/channel.nix ];
+      virtualisation.writableStore = true;
+
+      containers.tmpfs =
+        {
+          autoStart = true;
+          tmpfs = [
+            # Mount var as a tmpfs
+            "/var"
+
+            # Add a nested mount inside a tmpfs
+            "/var/log"
+
+            # Add a tmpfs on a path that does not exist
+            "/some/random/path"
+          ];
+          config = { };
+        };
+
+      virtualisation.additionalPaths = [ pkgs.stdenv ];
+    };
+
+  testScript = ''
+      machine.wait_for_unit("default.target")
+      assert "tmpfs" in machine.succeed("nixos-container list")
+
+      with subtest("tmpfs container is up"):
+          assert "up" in machine.succeed("nixos-container status tmpfs")
+
+
+      def tmpfs_cmd(command):
+          return f"nixos-container run tmpfs -- {command} 2>/dev/null"
+
+
+      with subtest("/var is mounted as a tmpfs"):
+          machine.succeed(tmpfs_cmd("mountpoint -q /var"))
+
+      with subtest("/var/log is mounted as a tmpfs"):
+          assert "What: tmpfs" in machine.succeed(
+              tmpfs_cmd("systemctl status var-log.mount --no-pager")
+          )
+          machine.succeed(tmpfs_cmd("mountpoint -q /var/log"))
+
+      with subtest("/some/random/path is mounted as a tmpfs"):
+          assert "What: tmpfs" in machine.succeed(
+              tmpfs_cmd("systemctl status some-random-path.mount --no-pager")
+          )
+          machine.succeed(tmpfs_cmd("mountpoint -q /some/random/path"))
+
+      with subtest(
+          "files created in the container in a non-tmpfs directory are visible on the host."
+      ):
+          # This establishes legitimacy for the following tests
+          machine.succeed(
+              tmpfs_cmd("touch /root/test.file"),
+              tmpfs_cmd("ls -l  /root | grep -q test.file"),
+              "test -e /var/lib/containers/tmpfs/root/test.file",
+          )
+
+      with subtest(
+          "/some/random/path is writable and that files created there are not "
+          + "in the hosts container dir but in the tmpfs"
+      ):
+          machine.succeed(
+              tmpfs_cmd("touch /some/random/path/test.file"),
+              tmpfs_cmd("test -e /some/random/path/test.file"),
+          )
+          machine.fail("test -e /var/lib/containers/tmpfs/some/random/path/test.file")
+
+      with subtest(
+          "files created in the hosts container dir in a path where a tmpfs "
+          + "file system has been mounted are not visible to the container as "
+          + "the do not exist in the tmpfs"
+      ):
+          machine.succeed(
+              "touch /var/lib/containers/tmpfs/var/test.file",
+              "test -e /var/lib/containers/tmpfs/var/test.file",
+              "ls -l /var/lib/containers/tmpfs/var/ | grep -q test.file 2>/dev/null",
+          )
+          machine.fail(tmpfs_cmd("ls -l /var | grep -q test.file"))
+    '';
+})