Add --watchers flag to allow controller to respond automatically to Ingress or Service updates

controller/controller_test.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"reflect"
 	"testing"
+	"time"
 
 	"sigs.k8s.io/external-dns/endpoint"
 	"sigs.k8s.io/external-dns/internal/testutils"
@@ -151,3 +152,44 @@ func TestRunOnce(t *testing.T) {
 	// Validate that the mock source was called.
 	source.AssertExpectations(t)
 }
+
+// TestSourceEventHandler tests that the Controller can use a Source's registered handler as a callback.
+func TestSourceEventHandler(t *testing.T) {
+	source := new(testutils.MockSource)
+
+	handlerCh := make(chan bool)
+	timeoutCh := make(chan bool, 1)
+	stopChan := make(chan struct{}, 1)
+
+	ctrl := &Controller{
+		Source:   source,
+		Registry: nil,
+		Policy:   &plan.SyncPolicy{},
+	}
+
+	// Define and register a simple handler that sends a message to a channel to show it was called.
+	handler := func() error {
+		handlerCh <- true
+		return nil
+	}
+	// Example of preventing handler from being called more than once every 5 seconds.
+	ctrl.Source.AddEventHandler(handler, stopChan, 5*time.Second)
+
+	// Send timeout message after 10 seconds to fail test if handler is not called.
+	go func() {
+		time.Sleep(10 * time.Second)
+		timeoutCh <- true
+	}()
+
+	// Wait until we either receive a message from handlerCh or timeoutCh channel after 10 seconds.
+	select {
+	case msg := <-handlerCh:
+		assert.True(t, msg)
+	case <-timeoutCh:
+		assert.Fail(t, "timed out waiting for event handler to be called")
+	}
+
+	close(stopChan)
+	close(handlerCh)
+	close(timeoutCh)
+}

go.mod

@@ -57,6 +57,7 @@ require (
 	k8s.io/api v0.0.0-20190620084959-7cf5895f2711
 	k8s.io/apimachinery v0.0.0-20190612205821-1799e75a0719
 	k8s.io/client-go v10.0.0+incompatible
+	k8s.io/kubernetes v1.14.1
 )
 
 replace (

go.sum

@@ -795,6 +795,8 @@ k8s.io/helm v2.13.1+incompatible/go.mod h1:LZzlS4LQBHfciFOurYBFkCMTaZ0D1l+p0teMg
 k8s.io/kube-openapi v0.0.0-20190228160746-b3a7cee44a30 h1:TRb4wNWoBVrH9plmkp2q86FIDppkbrEXdXlxU3a3BMI=
 k8s.io/kube-openapi v0.0.0-20190228160746-b3a7cee44a30/go.mod h1:BXM9ceUBTj2QnfH2MK1odQs778ajze1RxcmP6S8RVVc=
 k8s.io/kubernetes v1.13.1/go.mod h1:ocZa8+6APFNC2tX1DZASIbocyYT5jHzqFVsY5aoB7Jk=
+k8s.io/kubernetes v1.14.1 h1:I9F52h5sqVxBmoSsBlNQ0YygNcukDilkpGxUbJRoBoY=
+k8s.io/kubernetes v1.14.1/go.mod h1:ocZa8+6APFNC2tX1DZASIbocyYT5jHzqFVsY5aoB7Jk=
 k8s.io/utils v0.0.0-20190308190857-21c4ce38f2a7/go.mod h1:8k8uAuAQ0rXslZKaEWd0c3oVhZz7sSzSiPnVZayjIX0=
 k8s.io/utils v0.0.0-20190607212802-c55fbcfc754a/go.mod h1:sZAwmy6armz5eXlNoLmJcl4F1QuKu7sr+mFQ0byX7Ew=
 mvdan.cc/unparam v0.0.0-20190720180237-d51796306d8f/go.mod h1:4G1h5nDURzA3bwVMZIVpwbkw+04kSxk3rAtzlimaUJw=

internal/testutils/mock_source.go

@@ -17,8 +17,9 @@ limitations under the License.
 package testutils
 
 import (
-	"github.com/stretchr/testify/mock"
+	"time"
 
+	"github.com/stretchr/testify/mock"
 	"sigs.k8s.io/external-dns/endpoint"
 )
 
@@ -38,3 +39,23 @@ func (m *MockSource) Endpoints() ([]*endpoint.Endpoint, error) {
 
 	return endpoints.([]*endpoint.Endpoint), args.Error(1)
 }
+
+// AddEventHandler adds an event handler function that's called when sources that support such a thing have changed.
+func (m *MockSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+	// Execute callback handler no more than once per minInterval, until a message on stopChan is received.
+	go func() {
+		var lastCallbackTime time.Time
+		for {
+			select {
+			case <-stopChan:
+				return
+			default:
+				now := time.Now()
+				if now.After(lastCallbackTime.Add(minInterval)) {
+					handler()
+					lastCallbackTime = time.Now()
+				}
+			}
+		}
+	}()
+}

main.go

@@ -22,6 +22,7 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	log "github.com/sirupsen/logrus"
@@ -93,9 +94,15 @@ func main() {
 
 	// Lookup all the selected sources by names and pass them the desired configuration.
 	sources, err := source.ByNames(&source.SingletonClientGenerator{
-		KubeConfig:     cfg.KubeConfig,
-		KubeMaster:     cfg.Master,
-		RequestTimeout: cfg.RequestTimeout,
+		KubeConfig: cfg.KubeConfig,
+		KubeMaster: cfg.Master,
+		// If update events are enabled, disable timeout.
+		RequestTimeout: func() time.Duration {
+			if cfg.UpdateEvents {
+				return 0
+			}
+			return cfg.RequestTimeout
+		}(),
 	}, cfg.Sources, sourceCfg)
 	if err != nil {
 		log.Fatal(err)
@@ -281,6 +288,13 @@ func main() {
 		Interval: cfg.Interval,
 	}
 
+	if cfg.UpdateEvents {
+		// Add RunOnce as the handler function that will be called when ingress/service sources have changed.
+		// Note that k8s Informers will perform an initial list operation, which results in the handler
+		// function initially being called for every Service/Ingress that exists limted by minInterval.
+		ctrl.Source.AddEventHandler(func() error { return ctrl.RunOnce(ctx) }, stopChan, 1*time.Minute)
+	}
+
 	if cfg.Once {
 		err := ctrl.RunOnce(ctx)
 		if err != nil {

pkg/apis/externaldns/types.go

@@ -108,6 +108,7 @@ type Config struct {
 	Interval                          time.Duration
 	Once                              bool
 	DryRun                            bool
+	UpdateEvents                      bool
 	LogFormat                         string
 	MetricsAddress                    string
 	LogLevel                          string
@@ -201,6 +202,7 @@ var defaultConfig = &Config{
 	Interval:                    time.Minute,
 	Once:                        false,
 	DryRun:                      false,
+	UpdateEvents:                false,
 	LogFormat:                   "text",
 	MetricsAddress:              ":7979",
 	LogLevel:                    logrus.InfoLevel.String(),
@@ -382,6 +384,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("interval", "The interval between two consecutive synchronizations in duration format (default: 1m)").Default(defaultConfig.Interval.String()).DurationVar(&cfg.Interval)
 	app.Flag("once", "When enabled, exits the synchronization loop after the first iteration (default: disabled)").BoolVar(&cfg.Once)
 	app.Flag("dry-run", "When enabled, prints DNS record changes rather than actually performing them (default: disabled)").BoolVar(&cfg.DryRun)
+	app.Flag("events", "When enabled, in addition to running every interval, the reconciliation loop will get triggered when supported sources change (default: disabled)").BoolVar(&cfg.UpdateEvents)
 
 	// Miscellaneous flags
 	app.Flag("log-format", "The format in which log messages are printed (default: text, options: text, json)").Default(defaultConfig.LogFormat).EnumVar(&cfg.LogFormat, "text", "json")

pkg/apis/externaldns/types_test.go

@@ -83,6 +83,7 @@ var (
 		Interval:                    time.Minute,
 		Once:                        false,
 		DryRun:                      false,
+		UpdateEvents:                false,
 		LogFormat:                   "text",
 		MetricsAddress:              ":7979",
 		LogLevel:                    logrus.InfoLevel.String(),
@@ -157,6 +158,7 @@ var (
 		Interval:                    10 * time.Minute,
 		Once:                        true,
 		DryRun:                      true,
+		UpdateEvents:                true,
 		LogFormat:                   "json",
 		MetricsAddress:              "127.0.0.1:9099",
 		LogLevel:                    logrus.DebugLevel.String(),
@@ -257,6 +259,7 @@ func TestParseFlags(t *testing.T) {
 				"--interval=10m",
 				"--once",
 				"--dry-run",
+				"--events",
 				"--log-format=json",
 				"--metrics-address=127.0.0.1:9099",
 				"--log-level=debug",
@@ -338,6 +341,7 @@ func TestParseFlags(t *testing.T) {
 				"EXTERNAL_DNS_INTERVAL":                     "10m",
 				"EXTERNAL_DNS_ONCE":                         "1",
 				"EXTERNAL_DNS_DRY_RUN":                      "1",
+				"EXTERNAL_DNS_EVENTS":                       "1",
 				"EXTERNAL_DNS_LOG_FORMAT":                   "json",
 				"EXTERNAL_DNS_METRICS_ADDRESS":              "127.0.0.1:9099",
 				"EXTERNAL_DNS_LOG_LEVEL":                    "debug",

source/cloudfoundry.go

@@ -18,6 +18,7 @@ package source
 
 import (
 	"net/url"
+	"time"
 
 	cfclient "github.com/cloudfoundry-community/go-cfclient"
 
@@ -36,6 +37,9 @@ func NewCloudFoundrySource(cfClient *cfclient.Client) (Source, error) {
 	}, nil
 }
 
+func (rs *cloudfoundrySource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}
+
 // Endpoints returns endpoint objects
 func (rs *cloudfoundrySource) Endpoints() ([]*endpoint.Endpoint, error) {
 	endpoints := []*endpoint.Endpoint{}

source/connector.go

@@ -64,3 +64,6 @@ func (cs *connectorSource) Endpoints() ([]*endpoint.Endpoint, error) {
 
 	return endpoints, nil
 }
+
+func (cs *connectorSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}

source/crd.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
+	"time"
 
 	log "github.com/sirupsen/logrus"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -108,6 +109,9 @@ func NewCRDSource(crdClient rest.Interface, namespace, kind string, scheme *runt
 	}, nil
 }
 
+func (cs *crdSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}
+
 // Endpoints returns endpoint objects.
 func (cs *crdSource) Endpoints() ([]*endpoint.Endpoint, error) {
 	endpoints := []*endpoint.Endpoint{}

source/dedup_source.go

@@ -17,6 +17,8 @@ limitations under the License.
 package source
 
 import (
+	"time"
+
 	log "github.com/sirupsen/logrus"
 
 	"sigs.k8s.io/external-dns/endpoint"
@@ -56,3 +58,7 @@ func (ms *dedupSource) Endpoints() ([]*endpoint.Endpoint, error) {
 
 	return result, nil
 }
+
+func (ms *dedupSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+	ms.source.AddEventHandler(handler, stopChan, minInterval)
+}

source/empty.go

@@ -16,11 +16,18 @@ limitations under the License.
 
 package source
 
-import "sigs.k8s.io/external-dns/endpoint"
+import (
+	"time"
+
+	"sigs.k8s.io/external-dns/endpoint"
+)
 
 // emptySource is a Source that returns no endpoints.
 type emptySource struct{}
 
+func (e *emptySource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}
+
 // Endpoints collects endpoints of all nested Sources and returns them in a single slice.
 func (e *emptySource) Endpoints() ([]*endpoint.Endpoint, error) {
 	return []*endpoint.Endpoint{}, nil

source/fake.go

@@ -54,6 +54,9 @@ func NewFakeSource(fqdnTemplate string) (Source, error) {
 	}, nil
 }
 
+func (sc *fakeSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}
+
 // Endpoints returns endpoint objects.
 func (sc *fakeSource) Endpoints() ([]*endpoint.Endpoint, error) {
 	endpoints := make([]*endpoint.Endpoint, 10)

source/gateway.go

@@ -173,6 +173,9 @@ func (sc *gatewaySource) Endpoints() ([]*endpoint.Endpoint, error) {
 	return endpoints, nil
 }
 
+func (sc *gatewaySource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}
+
 func (sc *gatewaySource) endpointsFromTemplate(config *istiomodel.Config) ([]*endpoint.Endpoint, error) {
 	// Process the whole template string
 	var buf bytes.Buffer

source/ingress.go

@@ -33,6 +33,7 @@ import (
 	extinformers "k8s.io/client-go/informers/extensions/v1beta1"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/cache"
+	"k8s.io/kubernetes/pkg/util/async"
 
 	"sigs.k8s.io/external-dns/endpoint"
 )
@@ -56,6 +57,7 @@ type ingressSource struct {
 	combineFQDNAnnotation    bool
 	ignoreHostnameAnnotation bool
 	ingressInformer          extinformers.IngressInformer
+	runner                   *async.BoundedFrequencyRunner
 }
 
 // NewIngressSource creates a new ingressSource with the given config.
@@ -91,7 +93,7 @@ func NewIngressSource(kubeClient kubernetes.Interface, namespace, annotationFilt
 
 	// wait for the local cache to be populated.
 	err = wait.Poll(time.Second, 60*time.Second, func() (bool, error) {
-		return ingressInformer.Informer().HasSynced() == true, nil
+		return ingressInformer.Informer().HasSynced(), nil
 	})
 	if err != nil {
 		return nil, fmt.Errorf("failed to sync cache: %v", err)
@@ -303,3 +305,32 @@ func targetsFromIngressStatus(status v1beta1.IngressStatus) endpoint.Targets {
 
 	return targets
 }
+
+func (sc *ingressSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+	// Add custom resource event handler
+	log.Debug("Adding (bounded) event handler for ingress")
+
+	maxInterval := 24 * time.Hour // handler will be called if it has not run in 24 hours
+	burst := 2                    // allow up to two handler burst calls
+	log.Debugf("Adding handler to BoundedFrequencyRunner with minInterval: %v, syncPeriod: %v, bursts: %d",
+		minInterval, maxInterval, burst)
+	sc.runner = async.NewBoundedFrequencyRunner("ingress-handler", func() {
+		_ = handler()
+	}, minInterval, maxInterval, burst)
+	go sc.runner.Loop(stopChan)
+
+	// run the handler function as soon as the BoundedFrequencyRunner will allow when an update occurs
+	sc.ingressInformer.Informer().AddEventHandler(
+		cache.ResourceEventHandlerFuncs{
+			AddFunc: func(obj interface{}) {
+				sc.runner.Run()
+			},
+			UpdateFunc: func(old interface{}, new interface{}) {
+				sc.runner.Run()
+			},
+			DeleteFunc: func(obj interface{}) {
+				sc.runner.Run()
+			},
+		},
+	)
+}

source/ingressroute.go

@@ -332,3 +332,6 @@ func parseContourLoadBalancerService(service string) (namespace, name string, er
 
 	return
 }
+
+func (sc *ingressRouteSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+}

source/multi_source.go

@@ -16,7 +16,11 @@ limitations under the License.
 
 package source
 
-import "sigs.k8s.io/external-dns/endpoint"
+import (
+	"time"
+
+	"sigs.k8s.io/external-dns/endpoint"
+)
 
 // multiSource is a Source that merges the endpoints of its nested Sources.
 type multiSource struct {
@@ -39,6 +43,12 @@ func (ms *multiSource) Endpoints() ([]*endpoint.Endpoint, error) {
 	return result, nil
 }
 
+func (ms *multiSource) AddEventHandler(handler func() error, stopChan <-chan struct{}, minInterval time.Duration) {
+	for _, s := range ms.children {
+		s.AddEventHandler(handler, stopChan, minInterval)
+	}
+}
+
 // NewMultiSource creates a new multiSource.
 func NewMultiSource(children []Source) Source {
 	return &multiSource{children: children}