OCM-21663 | feat: Allow min-replicas=0 for HCP nodepool autoscaling

pkg/machinepool/helper.go

@@ -263,8 +263,9 @@ func (r *ReplicaSizeValidation) MinReplicaValidator() interactive.Validator {
 		if err != nil {
 			return err
 		}
-		if r.Autoscaling && minReplicas < 1 && r.IsHostedCp {
-			return fmt.Errorf("min-replicas must be greater than zero")
+		if r.Autoscaling && minReplicas < 0 && r.IsHostedCp {
+			return fmt.Errorf("min-replicas must be a number that is 0 or greater when autoscaling is" +
+				" enabled")
 		}
 		if r.Autoscaling && minReplicas < 0 && !r.IsHostedCp {
 			return fmt.Errorf("min-replicas must be a number that is 0 or greater when autoscaling is" +

pkg/machinepool/helper_test.go

@@ -516,6 +516,59 @@ var _ = Describe("Machine pool min/max replicas validation", func() {
 			false,
 		),
 	)
+
+	DescribeTable("NodePool (HCP) min replicas validation",
+		func(minReplicas int, autoscaling bool, multiAZ bool, hasError bool) {
+			replicaSizeValidation := &ReplicaSizeValidation{
+				ClusterVersion: "openshift-v4.14.14",
+				MultiAz:        multiAZ,
+				Autoscaling:    autoscaling,
+				IsHostedCp:     true,
+			}
+			err := replicaSizeValidation.MinReplicaValidator()(minReplicas)
+			if hasError {
+				Expect(err).To(HaveOccurred())
+			} else {
+				Expect(err).ToNot(HaveOccurred())
+			}
+		},
+		Entry("Zero replicas - no autoscaling - should succeed",
+			0,
+			false,
+			false,
+			false,
+		),
+		Entry("Zero replicas - autoscaling - should succeed",
+			0,
+			true,
+			false,
+			false,
+		),
+		Entry("Negative replicas - autoscaling - should fail",
+			-1,
+			true,
+			false,
+			true,
+		),
+		Entry("One replica - autoscaling - should succeed",
+			1,
+			true,
+			false,
+			false,
+		),
+		Entry("Multi-AZ - 3 replicas - should succeed",
+			3,
+			true,
+			true,
+			false,
+		),
+		Entry("Multi-AZ - 2 replicas - should fail (not multiple of 3)",
+			2,
+			true,
+			true,
+			true,
+		),
+	)
 })
 
 var _ = Describe("CreateAwsNodePoolBuilder", func() {

pkg/machinepool/machinepool.go

@@ -2109,8 +2109,8 @@ func validateNodePoolEdit(cmd *cobra.Command, autoscaling bool, replicas int, mi
 		return fmt.Errorf("the number of machine pool replicas needs to be a non-negative integer")
 	}
 
-	if autoscaling && cmd.Flags().Changed("min-replicas") && minReplicas < 1 {
-		return fmt.Errorf("min-replicas must be greater than zero")
+	if autoscaling && cmd.Flags().Changed("min-replicas") && minReplicas < 0 {
+		return fmt.Errorf("min-replicas must be a non-negative number when autoscaling is set")
 	}
 
 	if autoscaling && cmd.Flags().Changed("max-replicas") && maxReplicas < 1 {

pkg/machinepool/machinepool_test.go

@@ -108,9 +108,13 @@ var _ = Describe("Machinepool and nodepool", func() {
 			asBuilder := cmv1.NewNodePoolAutoscaling().MaxReplica(4).MinReplica(2)
 			Expect(builder).To(Equal(asBuilder))
 		})
-		It("Test edit nodepool min-replicas < 1 when autoscaling is set", func() {
+		It("Test edit nodepool min-replicas = 0 when autoscaling is set - should succeed", func() {
 			err := validateNodePoolEdit(testCommand, true, 0, 0, 1)
-			Expect(err.Error()).To(Equal("min-replicas must be greater than zero"))
+			Expect(err).ToNot(HaveOccurred())
+		})
+		It("Test edit nodepool min-replicas < 0 when autoscaling is set - should fail", func() {
+			err := validateNodePoolEdit(testCommand, true, 0, -1, 1)
+			Expect(err.Error()).To(Equal("min-replicas must be a non-negative number when autoscaling is set"))
 		})
 		It("Test edit nodepool !autoscaling and replicas < 0 for nodepools", func() {
 			err := validateNodePoolEdit(testCommand, false, -1, 0, 0)

tests/e2e/hcp_machine_pool_test.go

@@ -424,7 +424,15 @@ var _ = Describe("HCP Machine Pool", labels.Feature.Machinepool, func() {
 				"--min-replicas", fmt.Sprintf("%v", zeroMinReplica),
 				"-y",
 			)
-			expectErrMsg := "ERR: min-replicas must be greater than zero"
+			Expect(err).ToNot(HaveOccurred())
+
+			By("Try to set machine pool min replica to negative value - should fail")
+			negativeMinReplica := -1
+			_, err = rosaClient.MachinePool.EditMachinePool(clusterID, mpName,
+				"--min-replicas", fmt.Sprintf("%v", negativeMinReplica),
+				"-y",
+			)
+			expectErrMsg := "ERR: min-replicas must be a non-negative number when autoscaling is set"
 			Expect(err).To(HaveOccurred())
 			Expect(err.Error()).Should(ContainSubstring(expectErrMsg))