fix: reorder drift checks to save on computation (aws#464)

* reorder drift

* tests

pkg/controllers/machine/disruption/drift.go

@@ -102,16 +102,18 @@ func (d *Drift) Reconcile(ctx context.Context, provisioner *v1alpha5.Provisioner
 // isDrifted will check if a machine is drifted from the fields in the provisioner.Spec and
 // the cloudprovider
 func (d *Drift) isDrifted(ctx context.Context, provisioner *v1alpha5.Provisioner, machine *v1alpha5.Machine) (cloudprovider.DriftReason, error) {
+	// First check for static drift or node requirements have drifted to save on API calls.
+	if reason := lo.FindOrElse([]cloudprovider.DriftReason{areStaticFieldsDrifted(provisioner, machine), areNodeRequirementsDrifted(provisioner, machine)}, "", func(i cloudprovider.DriftReason) bool {
+		return i != ""
+	}); reason != "" {
+		return reason, nil
+	}
+
 	driftedReason, err := d.cloudProvider.IsMachineDrifted(ctx, machine)
 	if err != nil {
 		return "", err
 	}
-
-	reason := lo.FindOrElse([]cloudprovider.DriftReason{driftedReason, areStaticFieldsDrifted(provisioner, machine), areNodeRequirementsDrifted(provisioner, machine)}, "", func(i cloudprovider.DriftReason) bool {
-		return i != ""
-	})
-
-	return reason, nil
+	return driftedReason, nil
 }
 
 // Eligible fields for static drift are described in the docs

pkg/controllers/machine/disruption/drift_test.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/aws/karpenter-core/pkg/apis/settings"
 	"github.com/aws/karpenter-core/pkg/apis/v1alpha5"
+	"github.com/aws/karpenter-core/pkg/controllers/machine/disruption"
 	controllerprov "github.com/aws/karpenter-core/pkg/controllers/provisioner"
 	"github.com/aws/karpenter-core/pkg/test"
 
@@ -63,6 +64,33 @@ var _ = Describe("Drift", func() {
 		machine = ExpectExists(ctx, env.Client, machine)
 		Expect(machine.StatusConditions().GetCondition(v1alpha5.MachineDrifted).IsTrue()).To(BeTrue())
 	})
+	It("should detect static drift before cloud provider drift", func() {
+		cp.Drifted = "drifted"
+		provisioner.Annotations = lo.Assign(provisioner.Annotations, map[string]string{
+			v1alpha5.ProvisionerHashAnnotationKey: "123456789",
+		})
+		ExpectApplied(ctx, env.Client, provisioner, machine)
+		ExpectReconcileSucceeded(ctx, disruptionController, client.ObjectKeyFromObject(machine))
+
+		machine = ExpectExists(ctx, env.Client, machine)
+		Expect(machine.StatusConditions().GetCondition(v1alpha5.MachineDrifted).IsTrue()).To(BeTrue())
+		Expect(machine.StatusConditions().GetCondition(v1alpha5.MachineDrifted).Reason).To(Equal(string(disruption.ProvisionerStaticallyDrifted)))
+	})
+	It("should detect node requirement drift before cloud provider drift", func() {
+		cp.Drifted = "drifted"
+		provisioner.Spec.Requirements = []v1.NodeSelectorRequirement{
+			v1.NodeSelectorRequirement{
+				Key:      v1.LabelInstanceTypeStable,
+				Operator: v1.NodeSelectorOpDoesNotExist,
+			},
+		}
+		ExpectApplied(ctx, env.Client, provisioner, machine)
+		ExpectReconcileSucceeded(ctx, disruptionController, client.ObjectKeyFromObject(machine))
+
+		machine = ExpectExists(ctx, env.Client, machine)
+		Expect(machine.StatusConditions().GetCondition(v1alpha5.MachineDrifted).IsTrue()).To(BeTrue())
+		Expect(machine.StatusConditions().GetCondition(v1alpha5.MachineDrifted).Reason).To(Equal(string(disruption.NodeRequirementDrifted)))
+	})
 	It("should not detect drift if the feature flag is disabled", func() {
 		cp.Drifted = "drifted"
 		ctx = settings.ToContext(ctx, test.Settings(settings.Settings{DriftEnabled: false}))