Add 'None' option to DNSPolicy and define DNSConfig field in Pod API

pkg/apis/core/types.go

@@ -2183,6 +2183,11 @@ const (
 	// DNSDefault indicates that the pod should use the default (as
 	// determined by kubelet) DNS settings.
 	DNSDefault DNSPolicy = "Default"
+
+	// DNSNone indicates that the pod should use empty DNS settings. DNS
+	// parameters such as nameservers and search paths should be defined via
+	// DNSConfig.
+	DNSNone DNSPolicy = "None"
 )
 
 // A node selector represents the union of the results of one or more label queries
@@ -2482,7 +2487,12 @@ type PodSpec struct {
 	// before the system actively tries to terminate the pod; value must be positive integer
 	// +optional
 	ActiveDeadlineSeconds *int64
-	// Required: Set DNS policy.
+	// Set DNS policy for the pod.
+	// Defaults to "ClusterFirst".
+	// Valid values are 'ClusterFirstWithHostNet', 'ClusterFirst', 'Default' or 'None'.
+	// DNS parameters given in DNSConfig will be merged with the policy selected with DNSPolicy.
+	// To have DNS options set along with hostNetwork, you have to specify DNS policy
+	// explicitly to 'ClusterFirstWithHostNet'.
 	// +optional
 	DNSPolicy DNSPolicy
 	// NodeSelector is a selector which must be true for the pod to fit on a node
@@ -2546,6 +2556,11 @@ type PodSpec struct {
 	// The higher the value, the higher the priority.
 	// +optional
 	Priority *int32
+	// Specifies the DNS parameters of a pod.
+	// Parameters specified here will be merged to the generated DNS
+	// configuration based on DNSPolicy.
+	// +optional
+	DNSConfig *PodDNSConfig
 }
 
 // HostAlias holds the mapping between IP and hostnames that will be injected as an entry in the
@@ -2635,6 +2650,35 @@ const (
 	PodQOSBestEffort PodQOSClass = "BestEffort"
 )
 
+// PodDNSConfig defines the DNS parameters of a pod in addition to
+// those generated from DNSPolicy.
+type PodDNSConfig struct {
+	// A list of DNS name server IP addresses.
+	// This will be appended to the base nameservers generated from DNSPolicy.
+	// Duplicated nameservers will be removed.
+	// +optional
+	Nameservers []string
+	// A list of DNS search domains for host-name lookup.
+	// This will be appended to the base search paths generated from DNSPolicy.
+	// Duplicated search paths will be removed.
+	// +optional
+	Searches []string
+	// A list of DNS resolver options.
+	// This will be merged with the base options generated from DNSPolicy.
+	// Duplicated entries will be removed. Resolution options given in Options
+	// will override those that appear in the base DNSPolicy.
+	// +optional
+	Options []PodDNSConfigOption
+}
+
+// PodDNSConfigOption defines DNS resolver options of a pod.
+type PodDNSConfigOption struct {
+	// Required.
+	Name string
+	// +optional
+	Value *string
+}
+
 // PodStatus represents information about the status of a pod. Status may trail the actual
 // state of a system.
 type PodStatus struct {

pkg/features/kube_features.go

@@ -188,6 +188,12 @@ const (
 	// Enable mount/attachment of Container Storage Interface (CSI) backed PVs
 	CSIPersistentVolume utilfeature.Feature = "CSIPersistentVolume"
 
+	// owner @MrHohn
+	// alpha: v1.9
+	//
+	// Support configurable pod DNS parameters.
+	CustomPodDNS utilfeature.Feature = "CustomPodDNS"
+
 	// owner: @screeley44
 	// alpha: v1.9
 	//
@@ -228,6 +234,7 @@ var defaultKubernetesFeatureGates = map[utilfeature.Feature]utilfeature.FeatureS
 	MountContainers:                             {Default: false, PreRelease: utilfeature.Alpha},
 	VolumeScheduling:                            {Default: false, PreRelease: utilfeature.Alpha},
 	CSIPersistentVolume:                         {Default: false, PreRelease: utilfeature.Alpha},
+	CustomPodDNS:                                {Default: false, PreRelease: utilfeature.Alpha},
 	BlockVolume:                                 {Default: false, PreRelease: utilfeature.Alpha},
 
 	// inherited features from generic apiserver, relisted here to get a conflict if it is changed

staging/src/k8s.io/api/core/v1/types.go

@@ -2431,6 +2431,11 @@ const (
 	// determined by kubelet) DNS settings.
 	DNSDefault DNSPolicy = "Default"
 
+	// DNSNone indicates that the pod should use empty DNS settings. DNS
+	// parameters such as nameservers and search paths should be defined via
+	// DNSConfig.
+	DNSNone DNSPolicy = "None"
+
 	DefaultTerminationGracePeriodSeconds = 30
 )
 
@@ -2760,10 +2765,12 @@ type PodSpec struct {
 	// Value must be a positive integer.
 	// +optional
 	ActiveDeadlineSeconds *int64 `json:"activeDeadlineSeconds,omitempty" protobuf:"varint,5,opt,name=activeDeadlineSeconds"`
-	// Set DNS policy for containers within the pod.
-	// One of 'ClusterFirstWithHostNet', 'ClusterFirst' or 'Default'.
+	// Set DNS policy for the pod.
 	// Defaults to "ClusterFirst".
-	// To have DNS options set along with hostNetwork, you have to specify DNS policy explicitly to 'ClusterFirstWithHostNet'.
+	// Valid values are 'ClusterFirstWithHostNet', 'ClusterFirst', 'Default' or 'None'.
+	// DNS parameters given in DNSConfig will be merged with the policy selected with DNSPolicy.
+	// To have DNS options set along with hostNetwork, you have to specify DNS policy
+	// explicitly to 'ClusterFirstWithHostNet'.
 	// +optional
 	DNSPolicy DNSPolicy `json:"dnsPolicy,omitempty" protobuf:"bytes,6,opt,name=dnsPolicy,casttype=DNSPolicy"`
 	// NodeSelector is a selector which must be true for the pod to fit on a node.
@@ -2856,6 +2863,11 @@ type PodSpec struct {
 	// The higher the value, the higher the priority.
 	// +optional
 	Priority *int32 `json:"priority,omitempty" protobuf:"bytes,25,opt,name=priority"`
+	// Specifies the DNS parameters of a pod.
+	// Parameters specified here will be merged to the generated DNS
+	// configuration based on DNSPolicy.
+	// +optional
+	DNSConfig *PodDNSConfig `json:"dnsConfig,omitempty" protobuf:"bytes,26,opt,name=dnsConfig"`
 }
 
 // HostAlias holds the mapping between IP and hostnames that will be injected as an entry in the
@@ -2923,6 +2935,35 @@ const (
 	PodQOSBestEffort PodQOSClass = "BestEffort"
 )
 
+// PodDNSConfig defines the DNS parameters of a pod in addition to
+// those generated from DNSPolicy.
+type PodDNSConfig struct {
+	// A list of DNS name server IP addresses.
+	// This will be appended to the base nameservers generated from DNSPolicy.
+	// Duplicated nameservers will be removed.
+	// +optional
+	Nameservers []string `json:"nameservers,omitempty" protobuf:"bytes,1,rep,name=nameservers"`
+	// A list of DNS search domains for host-name lookup.
+	// This will be appended to the base search paths generated from DNSPolicy.
+	// Duplicated search paths will be removed.
+	// +optional
+	Searches []string `json:"searches,omitempty" protobuf:"bytes,2,rep,name=searches"`
+	// A list of DNS resolver options.
+	// This will be merged with the base options generated from DNSPolicy.
+	// Duplicated entries will be removed. Resolution options given in Options
+	// will override those that appear in the base DNSPolicy.
+	// +optional
+	Options []PodDNSConfigOption `json:"options,omitempty" protobuf:"bytes,3,rep,name=options"`
+}
+
+// PodDNSConfigOption defines DNS resolver options of a pod.
+type PodDNSConfigOption struct {
+	// Required.
+	Name string `json:"name,omitempty" protobuf:"bytes,1,opt,name=name"`
+	// +optional
+	Value *string `json:"value,omitempty" protobuf:"bytes,2,opt,name=value"`
+}
+
 // PodStatus represents information about the status of a pod. Status may trail the actual
 // state of a system.
 type PodStatus struct {