metrics server (#338)

* metrics-server manifests

Signed-off-by: Artiom Diomin <kron82@gmail.com>

* Create metrics-server objects

Signed-off-by: Artiom Diomin <kron82@gmail.com>

* Deploy metrics-server

Signed-off-by: Artiom Diomin <kron82@gmail.com>

Gopkg.toml

@@ -38,6 +38,10 @@
   name = "k8s.io/apiextensions-apiserver"
   version = "kubernetes-1.13.1"
 
+[[constraint]]
+  name = "k8s.io/kube-aggregator"
+  version = "kubernetes-1.13.1"
+
 [[constraint]]
   name = "sigs.k8s.io/cluster-api"
   revision = "813b1fec840d79b37fe86778237b6db6d1cb959d"

config.yaml.dist

@@ -65,6 +65,11 @@ features:
   dynamic_audit_log:
     enable: false
 
+  # Opt-out from deploying metrics-server
+  # more info: https://github.com/kubernetes-incubator/metrics-server
+  metrics_server:
+    disable: false
+
 # The list of nodes can be overwritten by providing Terraform output.
 # You are strongly encouraged to provide an odd number of nodes and
 # have at least three of them.

examples/terraform/digitalocean/output.tf

@@ -40,9 +40,11 @@ output "kubeone_workers" {
     # following outputs will be parsed by kubeone and automatically merged into
     # corresponding (by name) worker definition
     fra1-1 = {
-      droplet_size  = "${var.droplet_size}"
-      region        = "${var.region}"
-      sshPublicKeys = ["${digitalocean_ssh_key.deployer.public_key}"]
+      replicas        = 3
+      operatingSystem = "ubuntu"
+      droplet_size    = "${var.droplet_size}"
+      region          = "${var.region}"
+      sshPublicKeys   = ["${digitalocean_ssh_key.deployer.public_key}"]
     }
   }
 }

pkg/cmd/root.go

@@ -24,6 +24,7 @@ import (
 
 	apiextensionsscheme "k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset/scheme"
 	"k8s.io/client-go/kubernetes/scheme"
+	apiregscheme "k8s.io/kube-aggregator/pkg/client/clientset_generated/clientset/scheme"
 	clusterscheme "sigs.k8s.io/cluster-api/pkg/client/clientset_generated/clientset/scheme"
 )
 
@@ -41,6 +42,10 @@ func Execute() {
 		panic(err)
 	}
 
+	if err := apiregscheme.AddToScheme(scheme.Scheme); err != nil {
+		panic(err)
+	}
+
 	rootCmd := newRoot()
 
 	if err := rootCmd.Execute(); err != nil {

pkg/config/cluster.go

@@ -337,6 +337,7 @@ func (m *WorkerConfig) Validate() error {
 type Features struct {
 	PodSecurityPolicy PodSecurityPolicy `json:"pod_security_policy"`
 	DynamicAuditLog   DynamicAuditLog   `json:"dynamic_audit_log"`
+	MetricsServer     MetricsServer     `json:"metrics_server"`
 }
 
 // PodSecurityPolicy feature flag
@@ -349,6 +350,11 @@ type DynamicAuditLog struct {
 	Enable bool `json:"enable"`
 }
 
+// MetricsServer feature flag
+type MetricsServer struct {
+	Disable bool `json:"disable"`
+}
+
 // MachineControllerConfig controls
 type MachineControllerConfig struct {
 	Deploy *bool `json:"deploy"`

pkg/features/activate.go

@@ -31,6 +31,10 @@ func Activate(ctx *util.Context) error {
 		return errors.Wrap(err, "failed to install PodSecurityPolicy")
 	}
 
+	if err := installMetricsServer(!ctx.Cluster.Features.MetricsServer.Disable, ctx); err != nil {
+		return errors.Wrap(err, "failed to install metrics-server")
+	}
+
 	return nil
 }
 

pkg/features/metrics-server.go

@@ -0,0 +1,30 @@
+/*
+Copyright 2019 The KubeOne Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package features
+
+import (
+	"github.com/kubermatic/kubeone/pkg/templates/metricsserver"
+	"github.com/kubermatic/kubeone/pkg/util"
+)
+
+func installMetricsServer(activate bool, ctx *util.Context) error {
+	if !activate {
+		return nil
+	}
+
+	return metricsserver.Deploy(ctx)
+}