outpost: rewrite kubernetes controller

passbook/outposts/controllers/k8s/base.py

@@ -0,0 +1,105 @@
+"""Base Kubernetes Reconciler"""
+from typing import Generic, TypeVar
+
+from kubernetes.client import V1ObjectMeta
+from kubernetes.client.rest import ApiException
+from structlog import get_logger
+
+from passbook import __version__
+from passbook.lib.sentry import SentryIgnoredException
+from passbook.outposts.models import Outpost
+
+# pylint: disable=invalid-name
+T = TypeVar("T")
+
+
+class ReconcileTrigger(SentryIgnoredException):
+    """Base trigger raised by child classes to notify us"""
+
+
+class NeedsRecreate(ReconcileTrigger):
+    """Exception to trigger a complete recreate of the Kubernetes Object"""
+
+
+class NeedsUpdate(ReconcileTrigger):
+    """Exception to trigger an update to the Kubernetes Object"""
+
+
+class KubernetesObjectReconciler(Generic[T]):
+    """Base Kubernetes Reconciler, handles the basic logic."""
+
+    def __init__(self, outpost: Outpost):
+        self.outpost = outpost
+        self.namespace = ""
+        self.logger = get_logger(
+            component=f"k8s-reconciler-{self.__class__.__name__}", outpost=outpost
+        )
+
+    def run(self):
+        """Create object if it doesn't exist, update if needed or recreate if needed."""
+        current = None
+        reference = self.get_reference_object()
+        try:
+            try:
+                current = self.retrieve()
+            except ApiException as exc:
+                if exc.status == 404:
+                    self.logger.debug("Failed to get current, triggering recreate")
+                    raise NeedsRecreate from exc
+                self.logger.debug("Other unhandled error", exc=exc)
+            else:
+                self.logger.debug("Got current, running reconcile")
+                self.reconcile(current, reference)
+        except NeedsRecreate:
+            self.logger.debug("Recreate requested")
+            if current:
+                self.logger.debug("Deleted old")
+                self.delete(current)
+            else:
+                self.logger.debug("No old found, creating")
+            self.logger.debug("Created")
+            self.create(reference)
+        except NeedsUpdate:
+            self.logger.debug("Updating")
+            self.update(current, reference)
+        else:
+            self.logger.debug("Nothing to do...")
+
+    def get_reference_object(self) -> T:
+        """Return object as it should be"""
+        raise NotImplementedError
+
+    def reconcile(self, current: T, reference: T):
+        """Check what operations should be done, should be raised as
+        ReconcileTrigger"""
+        raise NotImplementedError
+
+    def create(self, reference: T):
+        """API Wrapper to create object"""
+        raise NotImplementedError
+
+    def retrieve(self) -> T:
+        """API Wrapper to retrive object"""
+        raise NotImplementedError
+
+    def delete(self, reference: T):
+        """API Wrapper to delete object"""
+        raise NotImplementedError
+
+    def update(self, current: T, reference: T):
+        """API Wrapper to update object"""
+        raise NotImplementedError
+
+    def get_object_meta(self, **kwargs) -> V1ObjectMeta:
+        """Get common object metadata"""
+        return V1ObjectMeta(
+            namespace=self.namespace,
+            labels={
+                "app.kubernetes.io/name": f"passbook-{self.outpost.type.lower()}",
+                "app.kubernetes.io/instance": self.outpost.name,
+                "app.kubernetes.io/version": __version__,
+                "app.kubernetes.io/managed-by": "passbook.beryju.org",
+                "passbook.beryju.org/outpost-uuid": self.outpost.uuid.hex,
+            },
+            **kwargs,
+        )