filesystem: swap options

Under some plymouth configs, cryptsetup shows warnings on boot for
underspecified cryptoswap options.  This makes the warnings go away, but
we've hardcoded some options that may change in the future.

LP: #2063252

subiquity/common/filesystem/manipulator.py

@@ -180,11 +180,19 @@ class FilesystemManipulator:
 
     delete_lvm_partition = delete_logical_volume
 
+    cryptoswap_options = [
+        "cipher=aes-cbc-essiv:sha256",
+        "initramfs",
+        "plain",
+        "size=256",
+        "swap",
+    ]
+
     def create_cryptoswap(self, device):
         dmc = self.model.add_dm_crypt(
             device,
             keyfile="/dev/urandom",
-            options=["swap", "initramfs"],
+            options=self.cryptoswap_options,
         )
         self.create_filesystem(dmc, dict(fstype="swap"))
         return dmc

subiquity/server/controllers/tests/test_filesystem.py

@@ -466,6 +466,7 @@ class TestGuided(IsolatedAsyncioTestCase):
         self.controller = FilesystemController(self.app)
         self.controller.supports_resilient_boot = True
         self.controller._examine_systems_task.start_sync()
+        self.controller.cryptoswap_options = ["a", "b"]
         self.app.dr_cfg = DRConfig()
         self.app.base_model.source.current.type = "fsimage"
         self.app.base_model.source.current.variations = {
@@ -657,7 +658,7 @@ class TestGuided(IsolatedAsyncioTestCase):
         self.assertIsNone(swap.fs())
         [dmc] = self.model.all_dm_crypts()
         self.assertEqual("/dev/urandom", dmc.keyfile)
-        self.assertEqual(["swap", "initramfs"], dmc.options)
+        self.assertEqual(["a", "b"], dmc.options)
         self.assertEqual("swap", dmc.fs().fstype)
         [rpool] = self.model._all(type="zpool", pool="rpool")
         self.assertIsNone(rpool.path)