meta: add interactive_sections endpoint

A feature request for Desktop was to add the ability to retrieve, all at
once, the raw interactive-sections value from autoinstall.

subiquity/common/apidef.py

@@ -135,6 +135,9 @@ class API:
                 the list of components.  free-only choice must be made prior to
                 confirmation of filesystem changes"""
 
+        class interactive_sections:
+            def GET() -> Optional[List[str]]: ...
+
     class errors:
         class wait:
             def GET(error_ref: ErrorReportRef) -> ErrorReportRef:

subiquity/server/server.py

@@ -178,6 +178,11 @@ class MetaController:
         # enabling free only mode means disabling components
         self.app.base_model.mirror.disable_components(to_disable, enable)
 
+    async def interactive_sections_GET(self) -> Optional[List[str]]:
+        if self.app.autoinstall_config is None:
+            return None
+        return self.app.autoinstall_config.get('interactive-sections', None)
+
 
 def get_installer_password_from_cloudinit_log():
     try:

subiquity/server/tests/test_server.py

@@ -19,7 +19,9 @@ from unittest.mock import Mock
 
 from subiquitycore.utils import run_command
 from subiquitycore.tests import SubiTestCase
+from subiquitycore.tests.mocks import make_app
 from subiquity.server.server import (
+    MetaController,
     SubiquityServer,
     cloud_autoinstall_path,
     iso_autoinstall_path,
@@ -121,3 +123,25 @@ early-commands: ["{cmd}"]
                        'early-commands': [cmd],
                        'stuff': 'things'}
         self.assertEqual(after_early, self.server.autoinstall_config)
+
+
+class TestMetaController(SubiTestCase):
+    async def test_interactive_sections_not_present(self):
+        mc = MetaController(make_app())
+        mc.app.autoinstall_config = None
+        self.assertIsNone(await mc.interactive_sections_GET())
+
+    async def test_interactive_sections_empty(self):
+        mc = MetaController(make_app())
+        mc.app.autoinstall_config['interactive-sections'] = []
+        self.assertEqual([], await mc.interactive_sections_GET())
+
+    async def test_interactive_sections_all(self):
+        mc = MetaController(make_app())
+        mc.app.autoinstall_config['interactive-sections'] = ['*']
+        self.assertEqual(['*'], await mc.interactive_sections_GET())
+
+    async def test_interactive_sections_one(self):
+        mc = MetaController(make_app())
+        mc.app.autoinstall_config['interactive-sections'] = ['network']
+        self.assertEqual(['network'], await mc.interactive_sections_GET())