CRI: Add dns option, rename DNSOption to DNSConfig.

pkg/kubelet/api/v1alpha1/runtime/api.proto

@@ -73,12 +73,15 @@ message VersionResponse {
     optional string runtime_api_version = 4;
 }
 
-// DNSOption specifies the DNS servers and search domains.
-message DNSOption {
+// DNSConfig specifies the DNS servers and search domains.
+message DNSConfig {
     // List of DNS servers of the cluster.
     repeated string servers = 1;
     // List of DNS search domains of the cluster.
     repeated string searches = 2;
+    // List of DNS options. See https://linux.die.net/man/5/resolv.conf
+    // for all available options.
+    repeated string options = 3;
 }
 
 enum Protocol {
@@ -177,8 +180,8 @@ message PodSandboxConfig {
     // https://issues.k8s.io/24677. There *may* be future change of direction
     // for logging as the discussion carries on.
     optional string log_directory = 3;
-    // The DNS options for the sandbox.
-    optional DNSOption dns_options = 4;
+    // The DNS config for the sandbox.
+    optional DNSConfig dns_config = 4;
     // The port mappings for the sandbox.
     repeated PortMapping port_mappings = 5;
     // Labels are key value pairs that may be used to scope and select individual resources.

pkg/kubelet/dockershim/docker_sandbox.go

@@ -243,9 +243,10 @@ func makeSandboxDockerConfig(c *runtimeApi.PodSandboxConfig, image string) *dock
 	hc.PortBindings = portBindings
 
 	// Set DNS options.
-	if dnsOpts := c.GetDnsOptions(); dnsOpts != nil {
-		hc.DNS = dnsOpts.GetServers()
-		hc.DNSSearch = dnsOpts.GetSearches()
+	if dnsConfig := c.GetDnsConfig(); dnsConfig != nil {
+		hc.DNS = dnsConfig.GetServers()
+		hc.DNSSearch = dnsConfig.GetSearches()
+		hc.DNSOptions = dnsConfig.GetOptions()
 	}
 
 	// Apply resource options.

pkg/kubelet/kuberuntime/helpers.go

@@ -37,6 +37,11 @@ const (
 	minQuotaPeriod = 1000
 )
 
+var (
+	// The default dns opt strings
+	defaultDNSOptions = []string{"ndots:5"}
+)
+
 type podsByID []*kubecontainer.Pod
 
 func (b podsByID) Len() int           { return len(b) }

pkg/kubelet/kuberuntime/kuberuntime_sandbox.go

@@ -69,9 +69,10 @@ func (m *kubeGenericRuntimeManager) generatePodSandboxConfig(pod *api.Pod, attem
 		if err != nil {
 			return nil, err
 		}
-		podSandboxConfig.DnsOptions = &runtimeApi.DNSOption{
+		podSandboxConfig.DnsConfig = &runtimeApi.DNSConfig{
 			Servers:  dnsServers,
 			Searches: dnsSearches,
+			Options:  defaultDNSOptions,
 		}
 		// TODO: Add domain support in new runtime interface
 		hostname, _, err := m.runtimeHelper.GeneratePodHostNameAndDomain(pod)