Merge pull request #3098 from howardjohn/dns/dns-search

Add `dnsSearch` cluster option

images/base/files/usr/local/bin/entrypoint

@@ -417,7 +417,20 @@ enable_network_magic(){
 
   # now we can ensure that DNS is configured to use our IP
   cp /etc/resolv.conf /etc/resolv.conf.original
-  sed -e "s/${docker_embedded_dns_ip}/${docker_host_ip}/g" /etc/resolv.conf.original >/etc/resolv.conf
+  replaced="$(sed -e "s/${docker_embedded_dns_ip}/${docker_host_ip}/g" /etc/resolv.conf.original)"
+  if [[ "${KIND_DNS_SEARCH+x}" == "" ]]; then
+    # No DNS search set, just pass through as is
+    echo "$replaced" >/etc/resolv.conf
+  elif [[ -z "$KIND_DNS_SEARCH" ]]; then
+    # Empty search - remove all current search clauses
+    echo "$replaced" | grep -v "^search" >/etc/resolv.conf
+  else
+    # Search set - remove all current search clauses, and add the configured search
+    {
+      echo "search $KIND_DNS_SEARCH";
+      echo "$replaced" | grep -v "^search";
+    } >/etc/resolv.conf
+  fi
 
   local files_to_update=(
     /etc/kubernetes/manifests/etcd.yaml

pkg/apis/config/v1alpha4/types.go

@@ -189,6 +189,8 @@ type Networking struct {
 	// KubeProxyMode defines if kube-proxy should operate in iptables or ipvs mode
 	// Defaults to 'iptables' mode
 	KubeProxyMode ProxyMode `yaml:"kubeProxyMode,omitempty" json:"kubeProxyMode,omitempty"`
+	// DNSSearch defines the DNS search domain to use for nodes. If not set, this will be inherited from the host.
+	DNSSearch *[]string `yaml:"dnsSearch,omitempty" json:"dnsSearch,omitempty"`
 }
 
 // ClusterIPFamily defines cluster network IP family

pkg/cluster/internal/providers/docker/provision.go

@@ -199,6 +199,11 @@ func commonArgs(cluster string, cfg *config.Cluster, networkName string, nodeNam
 	if mountFuse() {
 		args = append(args, "--device", "/dev/fuse")
 	}
+
+	if cfg.Networking.DNSSearch != nil {
+		args = append(args, "-e", "KIND_DNS_SEARCH="+strings.Join(*cfg.Networking.DNSSearch, " "))
+	}
+
 	return args, nil
 }
 

pkg/cluster/internal/providers/podman/provision.go

@@ -164,6 +164,10 @@ func commonArgs(cfg *config.Cluster, networkName string, nodeNames []string) ([]
 		args = append(args, "--device", "/dev/fuse")
 	}
 
+	if cfg.Networking.DNSSearch != nil {
+		args = append(args, "-e", "KIND_DNS_SEARCH="+strings.Join(*cfg.Networking.DNSSearch, " "))
+	}
+
 	return args, nil
 }
 

pkg/internal/apis/config/convert_v1alpha4.go

@@ -85,6 +85,7 @@ func convertv1alpha4Networking(in *v1alpha4.Networking, out *Networking) {
 	out.KubeProxyMode = ProxyMode(in.KubeProxyMode)
 	out.ServiceSubnet = in.ServiceSubnet
 	out.DisableDefaultCNI = in.DisableDefaultCNI
+	out.DNSSearch = in.DNSSearch
 }
 
 func convertv1alpha4Mount(in *v1alpha4.Mount, out *Mount) {

pkg/internal/apis/config/types.go

@@ -150,6 +150,8 @@ type Networking struct {
 	DisableDefaultCNI bool
 	// KubeProxyMode defines if kube-proxy should operate in iptables or ipvs mode
 	KubeProxyMode ProxyMode
+	// DNSSearch defines the DNS search domain to use for nodes. If not set, this will be inherited from the host.
+	DNSSearch *[]string
 }
 
 // ClusterIPFamily defines cluster network IP family