templates: persist appliance metadata on install

Appliance fields that describe the appliance (vendor information, default
credentials, installation instructions...) were dropped when installing a
template. Keep them in a new appliance_metadata JSON column on the
templates table, filled by the appliance-to-template conversion for both
registry v1-6 and v8 (version level values override the appliance level
ones). The nested schema allows extra fields so future registry fields
persist without a migration.

tests/api/routes/controller/test_templates.py

@@ -173,6 +173,44 @@ class TestTemplateRoutes:
         assert response.status_code == status.HTTP_200_OK
         assert response.json()["netmiko_device_type"] == ""
 
+    async def test_template_appliance_metadata_roundtrip(self, app: FastAPI, client: AsyncClient) -> None:
+        """
+        Appliance metadata persists with the template: create, read back,
+        and replace on update. Unknown fields are kept (extra=allow) so that
+        future appliance registry fields do not vanish.
+        """
+
+        template_id = str(uuid.uuid4())
+        params = {
+            "template_id": template_id,
+            "name": "VPCS_METADATA",
+            "compute_id": "local",
+            "template_type": "vpcs",
+            "appliance_metadata": {
+                "vendor_name": "Test vendor",
+                "default_username": "admin",
+                "future_field": "kept",
+            },
+        }
+
+        response = await client.post(app.url_path_for("create_template"), json=params)
+        assert response.status_code == status.HTTP_201_CREATED
+        metadata = response.json()["appliance_metadata"]
+        assert metadata["vendor_name"] == "Test vendor"
+        assert metadata["default_username"] == "admin"
+        assert metadata["future_field"] == "kept"
+
+        # read back from the database
+        response = await client.get(app.url_path_for("get_template", template_id=template_id))
+        assert response.status_code == status.HTTP_200_OK
+        assert response.json()["appliance_metadata"] == metadata
+
+        # the metadata object is replaced as a whole on update
+        params = {"appliance_metadata": {"default_username": "root"}}
+        response = await client.put(app.url_path_for("update_template", template_id=template_id), json=params)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.json()["appliance_metadata"] == {"default_username": "root"}
+
     async def test_template_delete(self, app: FastAPI, client: AsyncClient) -> None:
 
         template_id = str(uuid.uuid4())

tests/controller/test_appliance_manager.py

@@ -97,6 +97,10 @@ async def test_install_docker_version_skips_image_resolution(monkeypatch):
     assert template["template_type"] == "docker"
     # the version image name is injected into the template
     assert template["image"] == "xrd:1.0"
+    # appliance metadata survives the install and validates through TemplateCreate
+    metadata = template["appliance_metadata"]
+    assert metadata["vendor_name"] == "Test vendor"
+    assert metadata["appliance_id"] == appliance.id
 
 
 @pytest.mark.asyncio

tests/controller/test_appliance_to_template.py

@@ -555,3 +555,69 @@ def test_v8_get_template_type():
 
     v6 = {"registry_version": 6, "docker": {"image": "test:latest"}}
     assert converter.get_template_type(v6, None) == "docker"
+
+
+def test_v8_appliance_metadata_copied_to_template():
+    """
+    Appliance metadata (vendor information, default credentials...) is kept
+    on the template instead of being dropped, with version level values
+    overriding the appliance level ones.
+    """
+
+    appliance = dict(VYOS_V8, default_username="vyos", default_password="vyospass")
+    version = dict(VYOS_V8["versions"][1], default_username="vyos145")
+
+    template = ApplianceToTemplate().new_template(appliance, version, "local")
+
+    metadata = template["appliance_metadata"]
+    assert metadata["appliance_id"] == VYOS_V8["appliance_id"]
+    assert metadata["vendor_name"] == "VyOS Inc."
+    assert metadata["status"] == "stable"
+    # the version level default_username overrides the appliance level one
+    assert metadata["default_username"] == "vyos145"
+    assert metadata["default_password"] == "vyospass"
+
+
+def test_v8_appliance_metadata_version_level_overrides():
+    appliance = dict(VYOS_V8, installation_instructions="appliance instructions")
+    version = dict(VYOS_V8["versions"][1], installation_instructions="version instructions")
+
+    template = ApplianceToTemplate().new_template(appliance, version, "local")
+
+    assert template["appliance_metadata"]["installation_instructions"] == "version instructions"
+
+
+def test_v6_appliance_metadata_copied_to_template():
+    """
+    Registry versions 1-6 appliances keep their metadata too (the fields
+    they have: the v8-only ones are simply absent).
+    """
+
+    appliance = {
+        "registry_version": 6,
+        "name": "SRLinux",
+        "category": "router",
+        "description": "Nokia SR Linux",
+        "vendor_name": "Nokia",
+        "docker": {"adapters": 35, "image": "ghcr.io/nokia/srlinux:latest"},
+    }
+
+    template = ApplianceToTemplate().new_template(appliance, None, "local")
+
+    metadata = template["appliance_metadata"]
+    assert metadata["description"] == "Nokia SR Linux"
+    assert metadata["vendor_name"] == "Nokia"
+    assert "default_username" not in metadata
+
+
+def test_no_appliance_metadata_when_appliance_has_none():
+    appliance = {
+        "registry_version": 8,
+        "name": "Test",
+        "category": "guest",
+        "settings": [{"name": "only", "template_type": "qemu", "template_properties": {"ram": 512}}],
+    }
+
+    template = ApplianceToTemplate().new_template(appliance, None, "local")
+
+    assert "appliance_metadata" not in template