refactor to avoid checking the labels in the live layer twice

subiquity/server/controllers/filesystem.py

@@ -22,7 +22,7 @@ import os
 import pathlib
 import subprocess
 import time
-from typing import Any, Callable, Dict, List, Optional, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 
 import attr
 import pyudev
@@ -184,6 +184,7 @@ class VariationInfo:
     capability_info: CapabilityInfo = attr.Factory(CapabilityInfo)
     min_size: Optional[int] = None
     system: Optional[SystemDetails] = None
+    needs_systems_mount: bool = False
 
     def is_core_boot_classic(self) -> bool:
         return self.label is not None
@@ -336,12 +337,14 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
             self._source_handler.cleanup()
             self._source_handler = None
 
-    async def _get_system(self, variation_name, label):
+    async def _get_system(
+        self, variation_name, label
+    ) -> Tuple[Optional[SystemDetails], bool]:
         systems = await self.app.snapdapi.v2.systems.GET()
         labels = {system.label for system in systems.systems}
         if label in labels:
             try:
-                system = await self.app.snapdapi.v2.systems[label].GET()
+                return await self.app.snapdapi.v2.systems[label].GET(), True
             except requests.exceptions.HTTPError as http_err:
                 log.warning("v2/systems/%s returned %s", label, http_err.response.text)
                 raise
@@ -349,16 +352,14 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
             try:
                 await self._mount_systems_dir(variation_name)
             except NoSnapdSystemsOnSource:
-                return None
+                return None, False
             try:
-                system = await self.app.snapdapi.v2.systems[label].GET()
+                return await self.app.snapdapi.v2.systems[label].GET(), False
             except requests.exceptions.HTTPError as http_err:
                 log.warning("v2/systems/%s returned %s", label, http_err.response.text)
                 raise
             finally:
                 await self._unmount_systems_dir()
-        log.debug("got system %s", system)
-        return system
 
     def info_for_system(self, name: str, label: str, system: SystemDetails):
         if len(system.volumes) > 1:
@@ -419,40 +420,16 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
 
         return info
 
-    async def _examine_systems(self):
+    def _maybe_disable_encryption(self, info: VariationInfo) -> None:
-        self._variation_info.clear()
-        catalog_entry = self.app.base_model.source.current
-        for name, variation in catalog_entry.variations.items():
-            system = None
-            label = variation.snapd_system_label
-            if label is not None:
-                system = await self._get_system(name, label)
-            log.debug("got system %s for variation %s", system, name)
-            if system is not None and len(system.volumes) > 0:
-                if not self.app.opts.enhanced_secureboot:
-                    log.debug("Not offering enhanced_secureboot: commandline disabled")
-                    continue
-                info = self.info_for_system(name, label, system)
-                if info is None:
-                    continue
         if self.model.bootloader != Bootloader.UEFI:
-                    log.debug(
+            log.debug("Disabling core boot based install options on non-UEFI " "system")
-                        "Disabling core boot based install options on non-UEFI "
-                        "system"
-                    )
             info.capability_info.disallow_if(
                 lambda cap: cap.is_core_boot(),
                 GuidedDisallowedCapabilityReason.NOT_UEFI,
-                        _(
+                _("Enhanced secure boot options only available on UEFI " "systems."),
-                            "Enhanced secure boot options only available on UEFI "
-                            "systems."
-                        ),
             )
         search_drivers = self.app.base_model.source.search_drivers
-                if (
+        if search_drivers is not SEARCH_DRIVERS_AUTOINSTALL_DEFAULT and search_drivers:
-                    search_drivers is not SEARCH_DRIVERS_AUTOINSTALL_DEFAULT
-                    and search_drivers
-                ):
             log.debug(
                 "Disabling core boot based install options as third-party "
                 "drivers selected"
@@ -465,16 +442,32 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
                     "third party drivers."
                 ),
             )
-                self._variation_info[name] = info
+
+    async def _examine_systems(self):
+        self._variation_info.clear()
+        catalog_entry = self.app.base_model.source.current
+        for name, variation in catalog_entry.variations.items():
+            system = None
+            label = variation.snapd_system_label
+            if label is not None:
+                system, in_live_layer = await self._get_system(name, label)
+            log.debug("got system %s for variation %s", system, name)
+            if system is not None and len(system.volumes) > 0:
+                if not self.app.opts.enhanced_secureboot:
+                    log.debug("Not offering enhanced_secureboot: commandline disabled")
+                    continue
+                info = self.info_for_system(name, label, system)
+                if info is None:
+                    continue
+                if not in_live_layer:
+                    info.needs_systems_mount = True
+                self._maybe_disable_encryption(info)
             elif catalog_entry.type.startswith("dd-"):
                 min_size = variation.size
-                self._variation_info[name] = VariationInfo.dd(
+                info = VariationInfo.dd(name=name, min_size=min_size)
-                    name=name, min_size=min_size
-                )
             else:
-                self._variation_info[name] = VariationInfo.classic(
+                info = VariationInfo.classic(name=name, min_size=variation.size)
-                    name=name, min_size=variation.size
+            self._variation_info[name] = info
-                )
 
     @with_context()
     async def apply_autoinstall_config(self, context=None):
@@ -865,12 +858,10 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
             offset = offset + structure.size
 
     async def guided_core_boot(self, disk: Disk):
+        if self._info.needs_systems_mount:
+            await self._mount_systems_dir(self._info.name)
         # Formatting for a core boot classic system relies on some curtin
         # features that are only available with v2 partitioning.
-        systems = await self.app.snapdapi.v2.systems.GET()
-        labels = {system.label for system in systems.systems}
-        if self._info.label not in labels:
-            await self._mount_systems_dir(self._info.name)
         self.model.storage_version = 2
         [volume] = self._info.system.volumes.values()
         self._on_volume = snapdapi.OnVolume.from_volume(volume)