feat: raise on patching charm container (#129)

* raise on patching charm container

* fix tes

* add error message for resource patch conflict

* ignored complexity issue on _patch

* remove override

* statix fix

Author: PietroPasotti

lib/charms/observability_libs/v0/kubernetes_compute_resources_patch.py

@@ -149,7 +149,7 @@ def setUp(self, *unused):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 8
+LIBPATCH = 9
 
 
 _Decimal = Union[Decimal, float, str, int]  # types that are potentially convertible to Decimal
@@ -584,6 +584,14 @@ def __init__(
                 will be observed to re-apply the patch.
         """
         super().__init__(charm, "{}_{}".format(self.__class__.__name__, container_name))
+
+        if container_name == "charm":
+            raise ValueError(
+                "Starting with juju 3.6.9, juju manages the charm container "
+                "constraints and you'll get errors by doing this if the charm is deployed "
+                "on higher juju versions."
+            )
+
         self._charm = charm
         self._container_name = container_name
         self.resource_reqs_func = resource_reqs_func
@@ -606,7 +614,7 @@ def __init__(
     def _on_config_changed(self, _):
         self._patch()
 
-    def _patch(self) -> None:
+    def _patch(self) -> None: # noqa: C901
         """Patch the Kubernetes resources created by Juju to limit cpu or mem.
 
         This method will keep on retrying to patch the kubernetes resource for a default duration of 20 seconds
@@ -657,7 +665,9 @@ def _patch(self) -> None:
         except ApiError as e:
             if e.status.code == 403:
                 msg = f"Kubernetes resources patch failed: `juju trust` this application. {e}"
-
+            elif e.status.code == 409:
+                msg = (f"Kubernetes resources patch failed: someone else (likely juju) "
+                       f"owns the resources you're trying to patch {e}")
             else:
                 msg = f"Kubernetes resources patch failed: {e}"
 

lib/charms/observability_libs/v1/cert_handler.py

@@ -44,7 +44,7 @@
 
 LIBID = "b5cd5cd580f3428fa5f59a8876dcbe6a"
 LIBAPI = 1
-LIBPATCH = 18
+LIBPATCH = 19
 
 VAULT_SECRET_LABEL = "cert-handler-private-vault"
 
@@ -621,7 +621,7 @@ def chain(self) -> Optional[str]:
         cert = self.get_cert()
         if not cert:
             return None
-        chain = cert.chain_as_pem_string()
+        chain = cert.chain_as_pem_string()  # type: ignore
         if cert.certificate not in chain:
             # add server cert to chain
             chain = cert.certificate + "\n\n" + chain

tests/unit/test_kubernetes_compute_resources.py

@@ -5,6 +5,7 @@
 from unittest.mock import MagicMock, Mock, patch
 
 import httpx
+import pytest
 import tenacity
 import yaml
 from charms.observability_libs.v0.kubernetes_compute_resources_patch import (
@@ -155,3 +156,28 @@ def test_is_valid_spec(self):
 
         self.assertFalse(is_valid_spec({"bad": "combo"}))
         self.assertFalse(is_valid_spec({"invalid-key": "1"}))
+
+
+@mock.patch(
+    "charms.observability_libs.v0.kubernetes_compute_resources_patch.ResourcePatcher.apply",
+    MagicMock(return_value=None),
+)
+@mock.patch(
+    "charms.observability_libs.v0.kubernetes_compute_resources_patch.ResourcePatcher.is_failed",
+    MagicMock(return_value=(False, "")),
+)
+@mock.patch("lightkube.core.client.GenericSyncClient")
+@mock.patch.object(
+                KubernetesComputeResourcesPatch,
+                "_namespace",
+                "test-namespace",
+            )
+def test_patch_charm_container_fails_with_warning(_):
+    # When we try to patch the charm container we get an error
+    mm = MagicMock()
+    with pytest.raises(ValueError):
+        KubernetesComputeResourcesPatch(
+            mm,
+            "charm",
+            resource_reqs_func=lambda: adjust_resource_requirements(None, None),
+        )