add args: startup_timeout for kubernetes plugin (#7068)

Signed-off-by: mangoyhuang <mangoyhuang@tencent.com>
Co-authored-by: mangoyhuang <mangoyhuang@tencent.com>

plugin/kubernetes/README.md

@@ -43,6 +43,7 @@ kubernetes [ZONES...] {
     fallthrough [ZONES...]
     ignore empty_service
     multicluster [ZONES...]
+    startup_timeout DURATION
 }
 ```
 
@@ -106,6 +107,8 @@ kubernetes [ZONES...] {
   Services API (MCS-API). Specifying this option is generally paired with the
   installation of an MCS-API implementation and the ServiceImport and ServiceExport
   CRDs. The plugin MUST be authoritative for the zones listed here.
+* `startup_timeout` specifies the **DURATION** value that limits the time to wait for informer cache synced 
+  when the kubernetes plugin starts. If not specified, the default timeout will be 5s.
 
 Enabling zone transfer is done by using the *transfer* plugin.
 
@@ -115,7 +118,7 @@ When CoreDNS starts with the *kubernetes* plugin enabled, it will delay serving
 until it can connect to the Kubernetes API and synchronize all object watches.  If this cannot happen within
 5 seconds, then CoreDNS will start serving DNS while the *kubernetes* plugin continues to try to connect
 and synchronize all object watches.  CoreDNS will answer SERVFAIL to any request made for a Kubernetes record
-that has not yet been synchronized.
+that has not yet been synchronized. You can also determine how long to wait by specifying `startup_timeout`.
 
 ## Monitoring Kubernetes Endpoints
 

plugin/kubernetes/kubernetes.go

@@ -48,7 +48,8 @@ type Kubernetes struct {
 	opts             dnsControlOpts
 	primaryZoneIndex int
 	localIPs         []net.IP
-	autoPathSearch   []string // Local search path from /etc/resolv.conf. Needed for autopath.
+	autoPathSearch   []string      // Local search path from /etc/resolv.conf. Needed for autopath.
+	startupTimeout   time.Duration // startupTimeout set timeout of startup
 }
 
 // Upstreamer is used to resolve CNAME or other external targets
@@ -276,8 +277,7 @@ func (k *Kubernetes) InitKubeCache(ctx context.Context) (onStart func() error, o
 			k.APIConn.Run()
 		}()
 
-		timeout := 5 * time.Second
-		timeoutTicker := time.NewTicker(timeout)
+		timeoutTicker := time.NewTicker(k.startupTimeout)
 		defer timeoutTicker.Stop()
 		logDelay := 500 * time.Millisecond
 		logTicker := time.NewTicker(logDelay)

plugin/kubernetes/setup.go

@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/coredns/caddy"
 	"github.com/coredns/coredns/core/dnsserver"
@@ -112,6 +113,7 @@ func ParseStanza(c *caddy.Controller) (*Kubernetes, error) {
 
 	k8s.Upstream = upstream.New()
 
+	k8s.startupTimeout = time.Second * 5
 	for c.NextBlock() {
 		switch c.Val() {
 		case "endpoint_pod_names":
@@ -231,6 +233,17 @@ func ParseStanza(c *caddy.Controller) (*Kubernetes, error) {
 			k8s.ClientConfig = config
 		case "multicluster":
 			k8s.opts.multiclusterZones = plugin.OriginsFromArgsOrServerBlock(c.RemainingArgs(), []string{})
+		case "startup_timeout":
+			args := c.RemainingArgs()
+			if len(args) == 0 {
+				return nil, c.ArgErr()
+			} else {
+				var err error
+				k8s.startupTimeout, err = time.ParseDuration(args[0])
+				if err != nil {
+					return nil, fmt.Errorf("failed to parse startup_timeout: %v, %s", args[0], err)
+				}
+			}
 		default:
 			return nil, c.Errf("unknown property '%s'", c.Val())
 		}

plugin/kubernetes/setup_test.go

@@ -4,6 +4,7 @@ import (
 	"slices"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/coredns/caddy"
 	"github.com/coredns/coredns/plugin/pkg/fall"
@@ -11,6 +12,8 @@ import (
 	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
+var defaultStartupTimeout = time.Second * 5
+
 func TestKubernetesParse(t *testing.T) {
 	tests := []struct {
 		input                          string // Corefile data as string
@@ -22,6 +25,7 @@ func TestKubernetesParse(t *testing.T) {
 		expectedNamespaceLabelSelector string // expected namespace label selector value
 		expectedPodMode                string
 		expectedFallthrough            fall.F
+		expectedStartupTimeout         time.Duration
 	}{
 		// positive
 		{
@@ -34,6 +38,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local test.local`,
@@ -45,6 +50,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -57,6 +63,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -70,6 +77,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -83,6 +91,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -96,6 +105,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -109,6 +119,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -122,6 +133,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -135,6 +147,7 @@ func TestKubernetesParse(t *testing.T) {
 			"istio-injection=enabled",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -149,6 +162,7 @@ func TestKubernetesParse(t *testing.T) {
 			"istio-injection=enabled",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local test.local {
@@ -165,6 +179,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Root,
+			defaultStartupTimeout,
 		},
 		// negative
 		{
@@ -179,6 +194,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -192,6 +208,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -205,6 +222,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -218,6 +236,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		// pods disabled
 		{
@@ -232,6 +251,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		// pods insecure
 		{
@@ -246,6 +266,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeInsecure,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		// pods verified
 		{
@@ -260,6 +281,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeVerified,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		// pods invalid
 		{
@@ -274,6 +296,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeVerified,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		// fallthrough with zones
 		{
@@ -288,6 +311,7 @@ func TestKubernetesParse(t *testing.T) {
 			"",
 			podModeDisabled,
 			fall.F{Zones: []string{"ip6.arpa.", "inaddr.arpa.", "foo.com."}},
+			defaultStartupTimeout,
 		},
 		// More than one Kubernetes not allowed
 		{
@@ -301,6 +325,7 @@ kubernetes cluster.local`,
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -314,6 +339,7 @@ kubernetes cluster.local`,
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -327,6 +353,7 @@ kubernetes cluster.local`,
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -340,6 +367,7 @@ kubernetes cluster.local`,
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
 		},
 		{
 			`kubernetes coredns.local {
@@ -353,6 +381,22 @@ kubernetes cluster.local`,
 			"",
 			podModeDisabled,
 			fall.Zero,
+			defaultStartupTimeout,
+		},
+		{
+			`kubernetes coredns.local {
+        kubeconfig file context
+        startup_timeout 1s
+}`,
+			false,
+			"",
+			1,
+			0,
+			"",
+			"",
+			podModeDisabled,
+			fall.Zero,
+			time.Second * 1,
 		},
 	}
 
@@ -414,6 +458,11 @@ kubernetes cluster.local`,
 		if !k8sController.Fall.Equal(test.expectedFallthrough) {
 			t.Errorf("Test %d: Expected kubernetes controller to be initialized with fallthrough '%v'. Instead found fallthrough '%v' for input '%s'", i, test.expectedFallthrough, k8sController.Fall, test.input)
 		}
+
+		// startupTimeout
+		if k8sController.startupTimeout.String() != test.expectedStartupTimeout.String() {
+			t.Errorf("Test %d: Expected kubernetes controller to be initialized with startupTimeout '%v'. Instead found startupTimeout '%v' for input '%s'", i, test.expectedStartupTimeout, k8sController.startupTimeout, test.input)
+		}
 	}
 }