Merge pull request #4041 from rajansandeep/corednskops

CoreDNS in Kops as an addon

docs/cluster_spec.md

@@ -266,6 +266,26 @@ Will make kube-scheduler use the scheduler policy from configmap "scheduler-poli
 
 Note that as of Kubernetes 1.8.0 kube-scheduler does not reload its configuration from configmap automatically. You will need to ssh into the master instance and restart the Docker container manually.
 
+### kubeDNS
+
+This block contains configurations for `kube-dns`.
+
+ ```yaml
+ spec:
+   kubeDNS:
+     provider: KubeDNS
+```
+
+Specifying KubeDNS will install kube-dns as the default service discovery.
+
+ ```yaml
+ spec:
+   kubeDNS:
+     provider: CoreDNS
+```
+
+This will install [CoreDNS](https://coredns.io/) instead of kube-dns.
+
 ### kubeControllerManager
 This block contains configurations for the `controller-manager`.
 

pkg/apis/kops/cluster.go

@@ -300,6 +300,8 @@ type KubeDNSConfig struct {
 	CacheMaxSize int `json:"cacheMaxSize,omitempty"`
 	// CacheMaxConcurrent is the maximum number of concurrent queries for dnsmasq
 	CacheMaxConcurrent int `json:"cacheMaxConcurrent,omitempty"`
+	// Provider indicates whether CoreDNS or kube-dns will be the default service discovery.
+	Provider string `json:"provider,omitempty"`
 }
 
 // ExternalDNSConfig are options of the dns-controller

pkg/apis/kops/v1alpha1/cluster.go

@@ -299,6 +299,8 @@ type KubeDNSConfig struct {
 	CacheMaxSize int `json:"cacheMaxSize,omitempty"`
 	// CacheMaxConcurrent is the maximum number of concurrent queries for dnsmasq
 	CacheMaxConcurrent int `json:"cacheMaxConcurrent,omitempty"`
+	// Provider indicates whether CoreDNS or kube-dns will be the default service discovery.
+	Provider string `json:"provider,omitempty"`
 }
 
 // ExternalDNSConfig are options of the dns-controller

pkg/apis/kops/v1alpha1/zz_generated.conversion.go

@@ -2099,6 +2099,7 @@ func autoConvert_v1alpha1_KubeDNSConfig_To_kops_KubeDNSConfig(in *KubeDNSConfig,
 	out.ServerIP = in.ServerIP
 	out.CacheMaxSize = in.CacheMaxSize
 	out.CacheMaxConcurrent = in.CacheMaxConcurrent
+	out.Provider = in.Provider
 	return nil
 }
 
@@ -2114,6 +2115,7 @@ func autoConvert_kops_KubeDNSConfig_To_v1alpha1_KubeDNSConfig(in *kops.KubeDNSCo
 	out.ServerIP = in.ServerIP
 	out.CacheMaxSize = in.CacheMaxSize
 	out.CacheMaxConcurrent = in.CacheMaxConcurrent
+	out.Provider = in.Provider
 	return nil
 }
 

pkg/apis/kops/v1alpha2/cluster.go

@@ -297,6 +297,8 @@ type KubeDNSConfig struct {
 	CacheMaxSize int `json:"cacheMaxSize,omitempty"`
 	// CacheMaxConcurrent is the maximum number of concurrent queries for dnsmasq
 	CacheMaxConcurrent int `json:"cacheMaxConcurrent,omitempty"`
+	// Provider indicates whether CoreDNS or kube-dns will be the default service discovery.
+	Provider string `json:"provider,omitempty"`
 }
 
 // ExternalDNSConfig are options of the dns-controller

pkg/apis/kops/v1alpha2/zz_generated.conversion.go

@@ -2363,6 +2363,7 @@ func autoConvert_v1alpha2_KubeDNSConfig_To_kops_KubeDNSConfig(in *KubeDNSConfig,
 	out.ServerIP = in.ServerIP
 	out.CacheMaxSize = in.CacheMaxSize
 	out.CacheMaxConcurrent = in.CacheMaxConcurrent
+	out.Provider = in.Provider
 	return nil
 }
 
@@ -2378,6 +2379,7 @@ func autoConvert_kops_KubeDNSConfig_To_v1alpha2_KubeDNSConfig(in *kops.KubeDNSCo
 	out.ServerIP = in.ServerIP
 	out.CacheMaxSize = in.CacheMaxSize
 	out.CacheMaxConcurrent = in.CacheMaxConcurrent
+	out.Provider = in.Provider
 	return nil
 }
 

pkg/apis/kops/validation/legacy.go

@@ -33,7 +33,7 @@ import (
 
 // legacy contains validation functions that don't match the apimachinery style
 
-// ValidateCluster is responsible for checking the validitity of the Cluster spec
+// ValidateCluster is responsible for checking the validity of the Cluster spec
 func ValidateCluster(c *kops.Cluster, strict bool) *field.Error {
 	fieldSpec := field.NewPath("Spec")
 	var err error
@@ -270,10 +270,7 @@ func ValidateCluster(c *kops.Cluster, strict bool) *field.Error {
 	// Check KubeDNS.ServerIP
 	if c.Spec.KubeDNS != nil {
 		serverIPString := c.Spec.KubeDNS.ServerIP
-		if serverIPString == "" {
-			return field.Required(fieldSpec.Child("KubeDNS", "ServerIP"), "Cluster did not have KubeDNS.ServerIP set")
-		}
-
+		if serverIPString != "" {
 			dnsServiceIP := net.ParseIP(serverIPString)
 			if dnsServiceIP == nil {
 				return field.Invalid(fieldSpec.Child("KubeDNS", "ServerIP"), serverIPString, "Cluster had an invalid KubeDNS.ServerIP")
@@ -290,6 +287,7 @@ func ValidateCluster(c *kops.Cluster, strict bool) *field.Error {
 				return field.Invalid(fieldSpec.Child("KubeDNS", "ServerIP"), serverIPString, "MasterKubelet ClusterDNS did not match cluster KubeDNS.ServerIP")
 			}
 		}
+	}
 
 	// Check CloudProvider
 	{

upup/models/cloudup/resources/addons/coredns.addons.k8s.io/k8s-1.6.yaml.template

@@ -0,0 +1,158 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: coredns
+  namespace: kube-system
+  labels:
+      kubernetes.io/cluster-service: "true"
+      k8s-addon: coredns.addons.k8s.io
+---
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: ClusterRole
+metadata:
+  labels:
+    kubernetes.io/bootstrapping: rbac-defaults
+    k8s-addon: coredns.addons.k8s.io
+  name: system:coredns
+rules:
+- apiGroups:
+  - ""
+  resources:
+  - endpoints
+  - services
+  - pods
+  - namespaces
+  verbs:
+  - list
+  - watch
+---
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: ClusterRoleBinding
+metadata:
+  annotations:
+    rbac.authorization.kubernetes.io/autoupdate: "true"
+  labels:
+    kubernetes.io/bootstrapping: rbac-defaults
+    k8s-addon: coredns.addons.k8s.io
+  name: system:coredns
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: system:coredns
+subjects:
+- kind: ServiceAccount
+  name: coredns
+  namespace: kube-system
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: coredns
+  namespace: kube-system
+  labels:
+      addonmanager.kubernetes.io/mode: EnsureExists
+data:
+  Corefile: |
+    .:53 {
+        errors
+        log
+        health
+        kubernetes {{ KubeDNS.Domain }}. in-addr.arpa ip6.arpa {
+          pods insecure
+          upstream
+          fallthrough in-addr.arpa ip6.arpa
+        }
+        prometheus :9153
+        proxy . /etc/resolv.conf
+        cache 30
+    }
+---
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: coredns
+  namespace: kube-system
+  labels:
+    k8s-app: kube-dns
+    k8s-addon: coredns.addons.k8s.io
+    kubernetes.io/cluster-service: "true"
+spec:
+  replicas: 2
+    strategy:
+      type: RollingUpdate
+      rollingUpdate:
+        maxUnavailable: 1
+  selector:
+    matchLabels:
+      k8s-app: kube-dns
+  template:
+    metadata:
+      labels:
+        k8s-app: kube-dns
+    spec:
+      serviceAccountName: coredns
+      tolerations:
+        - key: node-role.kubernetes.io/master
+          effect: NoSchedule
+        - key: "CriticalAddonsOnly"
+          operator: "Exists"
+      containers:
+      - name: coredns
+        image: coredns/coredns:1.0.6
+        imagePullPolicy: IfNotPresent
+        resources:
+          limits:
+            memory: 170Mi
+          requests:
+            cpu: 100m
+            memory: 70Mi
+        args: [ "-conf", "/etc/coredns/Corefile" ]
+        volumeMounts:
+        - name: config-volume
+          mountPath: /etc/coredns
+        ports:
+        - containerPort: 53
+          name: dns
+          protocol: UDP
+        - containerPort: 53
+          name: dns-tcp
+          protocol: TCP
+        livenessProbe:
+          httpGet:
+            path: /health
+            port: 8080
+            scheme: HTTP
+          initialDelaySeconds: 60
+          timeoutSeconds: 5
+          successThreshold: 1
+          failureThreshold: 5
+      dnsPolicy: Default
+      volumes:
+        - name: config-volume
+          configMap:
+            name: coredns
+            items:
+            - key: Corefile
+              path: Corefile
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: kube-dns
+  namespace: kube-system
+  labels:
+    k8s-addon: coredns.addons.k8s.io
+    k8s-app: kube-dns
+    kubernetes.io/cluster-service: "true"
+    kubernetes.io/name: "CoreDNS"
+spec:
+  selector:
+    k8s-app: kube-dns
+  clusterIP: {{ KubeDNS.ServerIP }}
+  ports:
+  - name: dns
+    port: 53
+    protocol: UDP
+  - name: dns-tcp
+    port: 53
+    protocol: TCP

upup/pkg/fi/cloudup/bootstrapchannelbuilder.go

@@ -131,6 +131,9 @@ func (b *BootstrapChannelBuilder) buildManifest() (*channelsapi.Addons, map[stri
 		}
 	}
 
+	kubeDNS := b.cluster.Spec.KubeDNS
+	if kubeDNS.Provider == "KubeDNS" || kubeDNS.Provider == "" {
+
 		{
 			key := "kube-dns.addons.k8s.io"
 			version := "1.14.10"
@@ -165,6 +168,29 @@ func (b *BootstrapChannelBuilder) buildManifest() (*channelsapi.Addons, map[stri
 				manifests[key+"-"+id] = "addons/" + location
 			}
 		}
+	}
+
+	if kubeDNS.Provider == "CoreDNS" {
+		{
+			key := "coredns.addons.k8s.io"
+			version := "1.0.6"
+
+			{
+				location := key + "/k8s-1.6.yaml"
+				id := "k8s-1.6"
+
+				addons.Spec.Addons = append(addons.Spec.Addons, &channelsapi.AddonSpec{
+					Name:              fi.String(key),
+					Version:           fi.String(version),
+					Selector:          map[string]string{"k8s-addon": key},
+					Manifest:          fi.String(location),
+					KubernetesVersion: ">=1.6.0",
+					Id:                id,
+				})
+				manifests[key+"-"+id] = "addons/" + location
+			}
+		}
+	}
 
 	{
 		key := "rbac.addons.k8s.io"