storage: autoinstall sizing-policy

Co-authored-by: Ryan Mounce <ryan@mounce.com.au>

documentation/autoinstall-reference.md

@@ -311,6 +311,24 @@ When using the "lvm" layout, LUKS encryption can be enabled by supplying a passw
 
 The default is to use the lvm layout.
 
+#### sizing-policy
+
+The lvm layout will, by default, attempt to leave room for snapshots and further expansion.  A sizing-policy key may be supplied to control this behavior.
+
+**type:** string (enumeration)
+**default:** scaled
+
+Supported values are:
+
+ * `scaled` -> adjust space allocated to the root LV based on space available to the VG
+ * `all` -> allocate all remaining VG space to the root LV
+
+The scaling system is currently as follows:
+ * Less than 10 GiB: use all remaining space for root filesystem
+ * Between 10-20 GiB: 10 GiB root filesystem
+ * Between 20-200 GiB: use half of remaining space for root filesystem
+ * Greater than 200 GiB: 100 GiB root filesystem
+
 #### action-based config
 
 For full flexibility, the installer allows storage configuration to be done using a syntax which is a superset of that supported by curtin, described at https://curtin.readthedocs.io/en/latest/topics/storage.html.

subiquity/common/tests/test_types.py

@@ -0,0 +1,32 @@
+# Copyright 2023 Canonical, Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import unittest
+
+from subiquity.common.types import SizingPolicy
+
+
+class TestSizingPolicy(unittest.TestCase):
+    def test_all(self):
+        actual = SizingPolicy.from_string('all')
+        self.assertEqual(SizingPolicy.ALL, actual)
+
+    def test_scaled_size(self):
+        actual = SizingPolicy.from_string('scaled')
+        self.assertEqual(SizingPolicy.SCALED, actual)
+
+    def test_default(self):
+        actual = SizingPolicy.from_string(None)
+        self.assertEqual(SizingPolicy.SCALED, actual)

subiquity/common/types.py

@@ -379,6 +379,14 @@ class SizingPolicy(enum.Enum):
     SCALED = enum.auto()
     ALL = enum.auto()
 
+    @classmethod
+    def from_string(cls, value):
+        if value is None or value == 'scaled':
+            return cls.SCALED
+        if value == 'all':
+            return cls.ALL
+        raise Exception(f'Unknown SizingPolicy value {value}')
+
 
 @attr.s(auto_attribs=True)
 class GuidedResizeValues:

subiquity/server/controllers/filesystem.py

@@ -976,8 +976,11 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
         else:
             capability = GuidedCapability.DIRECT
         password = layout.get('password', None)
-        await self.guided(GuidedChoiceV2(target=target, capability=capability,
-                                         password=password))
+        sizing_policy = SizingPolicy.from_string(
+                layout.get('sizing-policy', None))
+        await self.guided(
+                GuidedChoiceV2(target=target, capability=capability,
+                               password=password, sizing_policy=sizing_policy))
 
     def validate_layout_mode(self, mode):
         if mode not in ('reformat_disk', 'use_gap'):