feat(models): add SnapInfo model for snapd response (#908)

Author: PraaneshSelvaraj

craft_providers/actions/snap_installer.py

@@ -27,7 +27,7 @@
 import subprocess
 import urllib.parse
 from http import HTTPStatus
-from typing import TYPE_CHECKING, Any, cast
+from typing import TYPE_CHECKING, cast
 
 import pydantic
 import requests
@@ -40,6 +40,7 @@
     details_from_called_process_error,
 )
 from craft_providers.instance_config import InstanceConfiguration
+from craft_providers.models import SnapInfo
 from craft_providers.util import snap_cmd, temp_paths
 
 if TYPE_CHECKING:
@@ -126,7 +127,7 @@ def _pack_host_snap(*, snap_name: str, output: pathlib.Path) -> None:
     )
 
 
-def get_host_snap_info(snap_name: str) -> dict[str, Any]:
+def get_host_snap_info(snap_name: str) -> SnapInfo:
     """Get info about a snap installed on the host."""
     quoted_name = urllib.parse.quote(snap_name, safe="")
     url = f"http+unix://%2Frun%2Fsnapd.socket/v2/snaps/{quoted_name}"
@@ -137,7 +138,8 @@ def get_host_snap_info(snap_name: str) -> dict[str, Any]:
             brief="Unable to connect to snapd service."
         ) from error
     snap_info.raise_for_status()
-    return cast("dict[str, Any]", snap_info.json()["result"])
+    result = snap_info.json()["result"]
+    return SnapInfo.model_validate(result)
 
 
 def _get_target_snap_revision_from_snapd(
@@ -294,12 +296,15 @@ def _add_assertions_from_host(executor: Executor, snap_name: str) -> None:
     )
     snap_info = get_host_snap_info(snap_name)
 
+    if not snap_info.publisher:
+        raise ProviderError("Can't get assertion for snap with no publisher info.")
+
     try:
         with _get_assertions_file(
             snap_name=snap_name,
-            snap_id=snap_info["id"],
-            snap_revision=snap_info["revision"],
-            snap_publisher_id=snap_info["publisher"]["id"],
+            snap_id=snap_info.id,
+            snap_revision=snap_info.revision,
+            snap_publisher_id=snap_info.publisher.id,
         ) as host_assert_path:
             executor.push_file(
                 source=host_assert_path,
@@ -352,14 +357,14 @@ def inject_from_host(*, executor: Executor, snap_name: str, classic: bool) -> No
         )
 
     host_snap_info = get_host_snap_info(snap_name)
-    host_snap_base = host_snap_info.get("base", None)
+    host_snap_base = host_snap_info.base
     if host_snap_base:
         logger.debug(
             "Installing base snap %r for %r from host", host_snap_base, snap_name
         )
         inject_from_host(executor=executor, snap_name=host_snap_base, classic=False)
 
-    host_revision = host_snap_info["revision"]
+    host_revision = host_snap_info.revision
     target_revision = _get_snap_revision_ensuring_source(
         snap_name=snap_store_name,
         source=SNAP_SRC_HOST,

craft_providers/models/__init__.py

@@ -0,0 +1,21 @@
+#
+# Copyright 2026 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+"""Models representing application states."""
+
+from craft_providers.models.snaps import SnapInfo, SnapPublisher
+
+__all__ = ["SnapInfo", "SnapPublisher"]

craft_providers/models/snaps.py

@@ -0,0 +1,39 @@
+#
+# Copyright 2026 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+"""Pydantic models for snap metadata returned by snapd."""
+
+import pydantic
+
+
+class SnapPublisher(pydantic.BaseModel, extra="ignore"):
+    """Publisher information returned by snapd."""
+
+    id: str
+
+
+class SnapInfo(pydantic.BaseModel, extra="ignore"):
+    """Information about an installed snap returned by snapd."""
+
+    id: str
+    name: str | None = None
+    type: str | None = None
+    version: str | None = None
+    channel: str | None = None
+    confinement: str | None = None
+    revision: str
+    publisher: SnapPublisher | None = None
+    base: str | None = None

tests/integration/conftest.py

@@ -28,7 +28,6 @@
 import sys
 import tempfile
 from collections.abc import Callable, Generator
-from typing import cast
 
 import pytest
 from craft_providers import lxd, multipass
@@ -61,7 +60,7 @@ def snap_exists(snap_name: str) -> bool:
 
 def is_installed_dangerously(snap_name: str) -> bool:
     """Returns true if a snap is installed dangerously."""
-    return cast(str, get_host_snap_info(snap_name)["revision"]).startswith("x")
+    return get_host_snap_info(snap_name).revision.startswith("x")
 
 
 @pytest.fixture