pkg/types/defaults/installconfig: Set defaults for null replicas

We don't currently support configuring zero workers [1], largely
because some key operators still do not tolerate masters.  Still, some
users are attempting to work around our checks by leaving 'replicas'
unset (which ends up as nil in Go) [2].  This commit adjusts our
install-config defaulting to fill in the default replica counts when
the user provides machine-pool entries but leaves replicas unset.

[1]: #958
[2]: https://bugzilla.redhat.com/show_bug.cgi?id=1670005#c1

pkg/types/defaults/installconfig.go

@@ -9,6 +9,7 @@ import (
 	libvirtdefaults "github.com/openshift/installer/pkg/types/libvirt/defaults"
 	nonedefaults "github.com/openshift/installer/pkg/types/none/defaults"
 	openstackdefaults "github.com/openshift/installer/pkg/types/openstack/defaults"
+	"k8s.io/utils/pointer"
 )
 
 var (
@@ -43,23 +44,40 @@ func SetInstallConfigDefaults(c *types.InstallConfig) {
 			},
 		}
 	}
+	numberOfMasters := int64(3)
+	numberOfWorkers := int64(3)
+	if c.Platform.Libvirt != nil {
+		numberOfMasters = 1
+		numberOfWorkers = 1
+	}
 	if len(c.Machines) == 0 {
-		numberOfMasters := int64(3)
-		numberOfWorkers := int64(3)
-		if c.Platform.Libvirt != nil {
-			numberOfMasters = 1
-			numberOfWorkers = 1
-		}
 		c.Machines = []types.MachinePool{
 			{
 				Name:     "master",
-				Replicas: func(x int64) *int64 { return &x }(numberOfMasters),
+				Replicas: &numberOfMasters,
 			},
 			{
 				Name:     "worker",
-				Replicas: func(x int64) *int64 { return &x }(numberOfWorkers),
+				Replicas: &numberOfWorkers,
 			},
 		}
+	} else {
+		for i := range c.Machines {
+			switch c.Machines[i].Name {
+			case "master":
+				if c.Machines[i].Replicas == nil {
+					c.Machines[i].Replicas = &numberOfMasters
+				}
+			case "worker":
+				if c.Machines[i].Replicas == nil {
+					c.Machines[i].Replicas = &numberOfWorkers
+				}
+			default:
+				if c.Machines[i].Replicas == nil {
+					c.Machines[i].Replicas = pointer.Int64Ptr(0)
+				}
+			}
+		}
 	}
 	switch {
 	case c.Platform.AWS != nil:

pkg/types/defaults/installconfig_test.go

@@ -16,6 +16,7 @@ import (
 	nonedefaults "github.com/openshift/installer/pkg/types/none/defaults"
 	"github.com/openshift/installer/pkg/types/openstack"
 	openstackdefaults "github.com/openshift/installer/pkg/types/openstack/defaults"
+	"k8s.io/utils/pointer"
 )
 
 func defaultInstallConfig() *types.InstallConfig {
@@ -192,7 +193,10 @@ func TestSetInstallConfigDefaults(t *testing.T) {
 			},
 			expected: func() *types.InstallConfig {
 				c := defaultInstallConfig()
-				c.Machines = []types.MachinePool{{Name: "test-machine"}}
+				c.Machines = []types.MachinePool{{
+					Name: "test-machine",
+					Replicas: pointer.Int64Ptr(0),
+				}}
 				return c
 			}(),
 		},