allow specification of initial kubelet version in machines file (#122)

* allow specification of initial kubelet version in machines file

* Add test for allowing specification of kubelet version without controlPlane version

Co-authored-by: weave-e2e-quickstart <58864910+weave-e2e-quickstart@users.noreply.github.com>

pkg/cluster/machine/machine.go

@@ -169,7 +169,8 @@ func validateVersions(machines []*clusterv1.Machine) field.ErrorList {
 				fmt.Sprintf("inconsistent kubelet version, expected \"%s\"", reference)))
 		}
 
-		if IsMaster(m) && m.Spec.Versions.ControlPlane != reference {
+		controlPlaneVersion := m.Spec.Versions.ControlPlane
+		if IsMaster(m) && controlPlaneVersion != "" && controlPlaneVersion != reference {
 			errors = append(errors, field.Invalid(
 				machinePath(i, "spec", "versions", "controlPlane"),
 				m.Spec.Versions.ControlPlane,

pkg/cluster/machine/machine_test.go

@@ -96,6 +96,41 @@ const machinesValid = `items:
       kubelet: "1.10.12"
 `
 
+const machinesValidWithOnlyKubeletVersion = `items:
+- apiVersion: "cluster.k8s.io/v1alpha1"
+  kind: Machine
+  metadata:
+    generateName: master-
+    labels:
+      set: master
+  spec:
+    providerSpec:
+      value:
+        apiVersion: "baremetalproviderspec/v1alpha1"
+        kind: "BareMetalMachineProviderSpec"
+        address: "172.17.8.101"
+    versions:
+      kubelet: "1.10.12"
+- apiVersion: "cluster.k8s.io/v1alpha1"
+  kind: Machine
+  metadata:
+    generateName: node-
+    labels:
+      set: node
+  spec:
+    providerSpec:
+      value:
+        apiVersion: "baremetalproviderspec/v1alpha1"
+        kind: "BareMetalMachineProviderSpec"
+        address: "172.17.8.102"
+        authenticationWebhook:
+          cacheTTL: 2m0s
+          server:
+            url: http://127.0.0.1:5000/authenticate
+    versions:
+      kubelet: "1.10.12"
+`
+
 // A machine doesn't have a matching Kubelet version.
 const machinesInconsistentKubeletVersion = `items:
 - apiVersion: "cluster.k8s.io/v1alpha1"
@@ -234,6 +269,7 @@ func TestValidateMachines(t *testing.T) {
 		errors []string
 	}{
 		{machinesValid, []string{}},
+		{machinesValidWithOnlyKubeletVersion, []string{}},
 		{machinesInconsistentKubeletVersion, []string{
 			"machines[1].spec.versions.kubelet",
 		}},