[release-4.20] OCPBUGS-61896: set appropriate rolling update settings

bindata/oauth-openshift/deployment.yaml

@@ -9,7 +9,8 @@ spec:
   strategy:
     type: RollingUpdate
     rollingUpdate:
-      maxUnavailable: 1
+      # those are being adjusted for each control plane size by the deployment controller
+      maxUnavailable: 0
       maxSurge: 0
   selector:
     matchLabels:

pkg/controllers/deployment/deployment_controller.go

@@ -11,6 +11,7 @@ import (
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/util/intstr"
 	"k8s.io/client-go/informers"
 	coreinformers "k8s.io/client-go/informers/core/v1"
 	"k8s.io/client-go/kubernetes"
@@ -253,12 +254,17 @@ func (c *oauthServerDeploymentSyncer) Sync(ctx context.Context, syncContext fact
 		return nil, false, append(errs, fmt.Errorf("unable to ensure at most one pod per node: %v", err))
 	}
 
-	// Set the replica count to the number of master nodes.
-	masterNodeCount, err := c.countNodes(expectedDeployment.Spec.Template.Spec.NodeSelector)
+	// Set the replica count to the number of control plane nodes.
+	controlPlaneCount, err := c.countNodes(expectedDeployment.Spec.Template.Spec.NodeSelector)
 	if err != nil {
-		return nil, false, append(errs, fmt.Errorf("failed to determine number of master nodes: %v", err))
+		return nil, false, append(errs, fmt.Errorf("failed to determine number of control plane nodes: %v", err))
 	}
-	expectedDeployment.Spec.Replicas = masterNodeCount
+	if controlPlaneCount == nil {
+		return nil, false, append(errs, fmt.Errorf("found nil control plane nodes count"))
+	}
+
+	expectedDeployment.Spec.Replicas = controlPlaneCount
+	setRollingUpdateParameters(*controlPlaneCount, expectedDeployment)
 
 	deployment, _, err := resourceapply.ApplyDeployment(ctx, c.deployments,
 		syncContext.Recorder(),
@@ -311,3 +317,14 @@ func (c *oauthServerDeploymentSyncer) getConfigResourceVersions() ([]string, err
 
 	return configRVs, nil
 }
+
+// Given the control plane sizes, we adjust the max unavailable and max surge values to mimic "MinAvailable".
+// We always ensure it is controlPlaneCount - 1, as this allows us to keep have at least a single replica running.
+// We also set MaxSurge to always be exactly the control plane count, as this allows us to more quickly replace failing
+// deployments with a new replica set. This does not clash with the pod anti affinity set above.
+func setRollingUpdateParameters(controlPlaneCount int32, deployment *appsv1.Deployment) {
+	maxUnavailable := intstr.FromInt32(max(controlPlaneCount-1, 1))
+	maxSurge := intstr.FromInt32(controlPlaneCount)
+	deployment.Spec.Strategy.RollingUpdate.MaxUnavailable = &maxUnavailable
+	deployment.Spec.Strategy.RollingUpdate.MaxSurge = &maxSurge
+}

pkg/controllers/deployment/deployment_controller_test.go

@@ -0,0 +1,101 @@
+package deployment
+
+import (
+	"testing"
+
+	appsv1 "k8s.io/api/apps/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
+)
+
+func TestSetRollingUpdateParameters(t *testing.T) {
+	testCases := []struct {
+		name                   string
+		controlPlaneCount      int32
+		expectedMaxUnavailable int32
+		expectedMaxSurge       int32
+	}{
+		{
+			name:                   "single control plane node",
+			controlPlaneCount:      1,
+			expectedMaxUnavailable: 1, // max(1-1, 1) = max(0, 1) = 1
+			expectedMaxSurge:       1,
+		},
+		{
+			name:                   "two control plane nodes",
+			controlPlaneCount:      2,
+			expectedMaxUnavailable: 1, // max(2-1, 1) = max(1, 1) = 1
+			expectedMaxSurge:       2,
+		},
+		{
+			name:                   "three control plane nodes",
+			controlPlaneCount:      3,
+			expectedMaxUnavailable: 2, // max(3-1, 1) = max(2, 1) = 2
+			expectedMaxSurge:       3,
+		},
+		{
+			name:                   "four control plane nodes",
+			controlPlaneCount:      4,
+			expectedMaxUnavailable: 3, // max(4-1, 1) = max(3, 1) = 3
+			expectedMaxSurge:       4,
+		},
+		{
+			name:                   "five control plane nodes",
+			controlPlaneCount:      5,
+			expectedMaxUnavailable: 4, // max(5-1, 1) = max(4, 1) = 4
+			expectedMaxSurge:       5,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Create a test deployment with rolling update strategy
+			deployment := &appsv1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "test-deployment",
+					Namespace: "test-namespace",
+				},
+				Spec: appsv1.DeploymentSpec{
+					Strategy: appsv1.DeploymentStrategy{
+						Type: appsv1.RollingUpdateDeploymentStrategyType,
+						RollingUpdate: &appsv1.RollingUpdateDeployment{
+							MaxUnavailable: &intstr.IntOrString{Type: intstr.Int, IntVal: 0},
+							MaxSurge:       &intstr.IntOrString{Type: intstr.Int, IntVal: 0},
+						},
+					},
+				},
+			}
+
+			// Call the function under test
+			setRollingUpdateParameters(tc.controlPlaneCount, deployment)
+
+			// Verify MaxUnavailable is set correctly
+			if deployment.Spec.Strategy.RollingUpdate.MaxUnavailable == nil {
+				t.Errorf("MaxUnavailable should not be nil")
+			} else {
+				actualMaxUnavailable := deployment.Spec.Strategy.RollingUpdate.MaxUnavailable.IntVal
+				if actualMaxUnavailable != tc.expectedMaxUnavailable {
+					t.Errorf("Expected MaxUnavailable to be %d, got %d", tc.expectedMaxUnavailable, actualMaxUnavailable)
+				}
+			}
+
+			// Verify MaxSurge is set correctly
+			if deployment.Spec.Strategy.RollingUpdate.MaxSurge == nil {
+				t.Errorf("MaxSurge should not be nil")
+			} else {
+				actualMaxSurge := deployment.Spec.Strategy.RollingUpdate.MaxSurge.IntVal
+				if actualMaxSurge != tc.expectedMaxSurge {
+					t.Errorf("Expected MaxSurge to be %d, got %d", tc.expectedMaxSurge, actualMaxSurge)
+				}
+			}
+
+			// Verify the values are of type Int (not String)
+			if deployment.Spec.Strategy.RollingUpdate.MaxUnavailable.Type != intstr.Int {
+				t.Errorf("Expected MaxUnavailable to be of type Int, got %v", deployment.Spec.Strategy.RollingUpdate.MaxUnavailable.Type)
+			}
+			if deployment.Spec.Strategy.RollingUpdate.MaxSurge.Type != intstr.Int {
+				t.Errorf("Expected MaxSurge to be of type Int, got %v", deployment.Spec.Strategy.RollingUpdate.MaxSurge.Type)
+			}
+		})
+	}
+}