source: add ability to select source in autoinstall

The source autoinstall section now supports the "id" field where the
user can supply the ID of a source, e.g., "ubuntu-server" or
"ubuntu-server-minimal".

If the field is not supplied, the installation will use the source
declared default: true (if any) in the source catalog. Otherwise, it the
first source declared will be used.

Signed-off-by: Olivier Gayot <olivier.gayot@canonical.com>

autoinstall-schema.json

@@ -123,6 +123,9 @@
             "properties": {
                 "search_drivers": {
                     "type": "boolean"
+                },
+                "id": {
+                    "type": "string"
                 }
             },
             "required": [

examples/autoinstall-user-data.yaml

@@ -13,6 +13,8 @@ late-commands:
   - echo a
 keyboard:
   layout: gb
+source:
+  id: ubuntu-server-minimal
 updates: security
 user-data:
   users:

scripts/runtests.sh

@@ -225,8 +225,11 @@ LANG=C.UTF-8 timeout --foreground 60 \
     --output-base "$tmpdir" \
     --machine-config examples/simple.json \
     --autoinstall examples/autoinstall-user-data.yaml \
-    --kernel-cmdline autoinstall
+    --kernel-cmdline autoinstall \
+    --source-catalog examples/install-sources.yaml
 validate
+python3 scripts/check-yaml-fields.py "$tmpdir"/var/log/installer/autoinstall-user-data \
+        'autoinstall.source.id="ubuntu-server-minimal"'
 grep -q 'finish: subiquity/Install/install/postinstall/run_unattended_upgrades: SUCCESS: downloading and installing security updates' $tmpdir/subiquity-server-debug.log
 
 # The OOBE doesn't exist in WSL < 20.04

subiquity/models/source.py

@@ -88,6 +88,13 @@ class SourceModel:
         if self.current is None:
             self.current = self.sources[0]
 
+    def get_matching_source(self, id_: str) -> CatalogEntry:
+        """ Return a source object that has the ID requested. """
+        for source in self.sources:
+            if source.id == id_:
+                return source
+        raise KeyError
+
     def get_source(self):
         path = os.path.join(self._dir, self.current.path)
         if self.current.preinstalled_langs:

subiquity/server/controllers/source.py

@@ -13,6 +13,7 @@
 # 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 contextlib
 from typing import Any, Optional
 import os
 
@@ -59,6 +60,9 @@ class SourceController(SubiquityController):
              "search_drivers": {
                  "type": "boolean",
              },
+             "id": {
+                 "type": "string",
+             },
          },
          "required": ["search_drivers"],
     }
@@ -71,15 +75,19 @@ class SourceController(SubiquityController):
         super().__init__(app)
         self._handler = None
         self.source_path: Optional[str] = None
+        self.ai_source_id: Optional[str] = None
 
     def make_autoinstall(self):
-        return {"search_drivers": self.model.search_drivers}
+        return {
+                "search_drivers": self.model.search_drivers,
+                "id": self.model.current.id,
+               }
 
     def load_autoinstall_data(self, data: Any) -> None:
         if data is None:
             # For some reason, the schema validator does not reject
             # "source: null" despite "type" being "object"
-            data = self.autoinstall_default
+            data = {**self.autoinstall_default, "id": None}
 
         # search_drivers is marked required so the schema validator should
         # reject any missing data.
@@ -87,6 +95,15 @@ class SourceController(SubiquityController):
 
         self.model.search_drivers = data["search_drivers"]
 
+        # At this point, the model has not yet loaded the sources from the
+        # catalog. So we store the data and lean on apply_autoinstall_config.
+        self.ai_source_id = data.get("id")
+
+    async def apply_autoinstall_config(self) -> None:
+        if self.ai_source_id is None:
+            return
+        self.model.current = self.model.get_matching_source(self.ai_source_id)
+
     def start(self):
         path = '/cdrom/casper/install-sources.yaml'
         if self.app.opts.source_catalog is not None:
@@ -129,7 +146,6 @@ class SourceController(SubiquityController):
     async def POST(self, source_id: str,
                    search_drivers: bool = False) -> None:
         self.model.search_drivers = search_drivers
-        for source in self.model.sources:
+        with contextlib.suppress(KeyError):
-            if source.id == source_id:
+            self.model.current = self.model.get_matching_source(source_id)
-                self.model.current = source
         await self.configured()