Introduce resolver module to the CoreDNS plugin

Currently, ServiceImport and EndpointSlice processing are in separate components, with ServiceImports used for resolving non-headless service queries and EndpointSlice used for headless services. However, the upcoming ServiceImport aggregation changes will require direct coordination between ServiceImports and EndpointSlices for resolving DNS records. Thus, it makes sense to combine the processing in 'serviceimport.Map' and 'endpointslice.Map ' into a single component. A new 'resolver' module is introduced to contain a controller component that watches for ServiceImports and EndpointSlices and feeds them into a resolver component that builds internal structs used to provide DNSRecords on request. Subsequent commits will modify the plugin handler to user the resolver. Signed-off-by: Tom Pantelis <[email protected]>
submariner-io · Feb 28, 2023 · 6371e20 · 6371e20
1 parent 5de2960
commit 6371e20
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diff --git a/coredns/resolver/clusterip_service_test.go b/coredns/resolver/clusterip_service_test.go
diff --git a/coredns/resolver/controller.go b/coredns/resolver/controller.go
@@ -0,0 +1,111 @@
+/*
+SPDX-License-Identifier: Apache-2.0
+
+Copyright Contributors to the Submariner project.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package resolver
+
+import (
+	"github.com/pkg/errors"
+	"github.com/submariner-io/admiral/pkg/log"
+	"github.com/submariner-io/admiral/pkg/watcher"
+	"github.com/submariner-io/lighthouse/coredns/constants"
+	discovery "k8s.io/api/discovery/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/runtime"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+	mcsv1a1 "sigs.k8s.io/mcs-api/pkg/apis/v1alpha1"
+)
+
+var logger = log.Logger{Logger: logf.Log.WithName("Resolver")}
+
+type controller struct {
+	resolver *Interface
+	stopCh   chan struct{}
+}
+
+func NewController(r *Interface) *controller {
+	return &controller{
+		resolver: r,
+		stopCh:   make(chan struct{}),
+	}
+}
+
+func (c *controller) Start(config watcher.Config) error {
+	logger.Infof("Starting Resolver Controller")
+
+	config.ResourceConfigs = []watcher.ResourceConfig{
+		{
+			Name:                "EndpointSlice watcher",
+			ResourceType:        &discovery.EndpointSlice{},
+			SourceNamespace:     metav1.NamespaceAll,
+			SourceLabelSelector: labels.Set(map[string]string{discovery.LabelManagedBy: constants.LabelValueManagedBy}).String(),
+			Handler: watcher.EventHandlerFuncs{
+				OnCreateFunc: c.onEndpointSliceCreateOrUpdate,
+				OnUpdateFunc: c.onEndpointSliceCreateOrUpdate,
+				OnDeleteFunc: c.onEndpointSliceDelete,
+			},
+		},
+		{
+			Name:            "ServiceImport watcher",
+			ResourceType:    &mcsv1a1.ServiceImport{},
+			SourceNamespace: metav1.NamespaceAll,
+			Handler: watcher.EventHandlerFuncs{
+				OnCreateFunc: c.onServiceImportCreateOrUpdate,
+				OnUpdateFunc: c.onServiceImportCreateOrUpdate,
+				OnDeleteFunc: c.onServiceImportDelete,
+			},
+		},
+	}
+
+	resourceWatcher, err := watcher.New(&config)
+	if err != nil {
+		return errors.Wrap(err, "error creating the resource watcher")
+	}
+
+	err = resourceWatcher.Start(c.stopCh)
+	if err != nil {
+		return errors.Wrap(err, "error starting the resource watcher")
+	}
+
+	return nil
+}
+
+func (c *controller) Stop() {
+	close(c.stopCh)
+
+	logger.Infof("Resolver Controller stopped")
+}
+
+func (c *controller) onEndpointSliceCreateOrUpdate(obj runtime.Object, _ int) bool {
+	return c.resolver.PutEndpointSlice(obj.(*discovery.EndpointSlice))
+}
+
+func (c *controller) onEndpointSliceDelete(obj runtime.Object, _ int) bool {
+	c.resolver.RemoveEndpointSlice(obj.(*discovery.EndpointSlice))
+	return false
+}
+
+func (c *controller) onServiceImportCreateOrUpdate(obj runtime.Object, _ int) bool {
+	c.resolver.PutServiceImport(obj.(*mcsv1a1.ServiceImport))
+	return false
+}
+
+func (c *controller) onServiceImportDelete(obj runtime.Object, _ int) bool {
+	c.resolver.RemoveServiceImport(obj.(*mcsv1a1.ServiceImport))
+	return false
+}
diff --git a/coredns/resolver/controller_test.go b/coredns/resolver/controller_test.go
@@ -0,0 +1,114 @@
+/*
+SPDX-License-Identifier: Apache-2.0
+
+Copyright Contributors to the Submariner project.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package resolver_test
+
+import (
+	"context"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+	"github.com/submariner-io/lighthouse/coredns/resolver"
+	discovery "k8s.io/api/discovery/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	mcsv1a1 "sigs.k8s.io/mcs-api/pkg/apis/v1alpha1"
+)
+
+var _ = Describe("Controller", func() {
+	t := newTestDriver()
+
+	expDNSRecord := resolver.DNSRecord{
+		IP:          serviceIP1,
+		Ports:       []mcsv1a1.ServicePort{port1},
+		ClusterName: clusterID1,
+	}
+
+	When("a ServiceImport is created", func() {
+		var serviceImport *mcsv1a1.ServiceImport
+
+		BeforeEach(func() {
+			serviceImport = newClusterServiceImport(namespace1, service1, serviceIP1, clusterID1, port1)
+			t.createServiceImport(serviceImport)
+		})
+
+		Specify("GetDNSRecords should return the cluster's DNS record when requested", func() {
+			t.awaitDNSRecordsFound(namespace1, service1, clusterID1, "", false, expDNSRecord)
+		})
+
+		Context("and is subsequently deleted", func() {
+			Specify("GetDNSRecords should eventually return no DNS record found", func() {
+				t.awaitDNSRecords(namespace1, service1, clusterID1, "", true)
+
+				err := t.serviceImports.Namespace(serviceImport.Namespace).Delete(context.TODO(), serviceImport.Name, metav1.DeleteOptions{})
+				Expect(err).To(Succeed())
+
+				t.awaitDNSRecords(namespace1, service1, clusterID1, "", false)
+			})
+		})
+	})
+
+	When("an EndpointSlice is created", func() {
+		var endpointSlice *discovery.EndpointSlice
+
+		JustBeforeEach(func() {
+			endpointSlice = newClusterIPEndpointSlice(namespace1, service1, clusterID1, serviceIP1, true)
+			t.createEndpointSlice(endpointSlice)
+		})
+
+		Context("before a ServiceImport", func() {
+			Specify("GetDNSRecords should eventually deem the cluster healthy and return its DNS record", func() {
+				Consistently(func() bool {
+					_, _, found := t.resolver.GetDNSRecords(namespace1, service1, "", "")
+					return found
+				}).Should(BeFalse())
+
+				t.createServiceImport(newClusterServiceImport(namespace1, service1, serviceIP1, clusterID1, port1))
+
+				t.awaitDNSRecordsFound(namespace1, service1, clusterID1, "", false, expDNSRecord)
+			})
+		})
+
+		Context("after a ServiceImport", func() {
+			BeforeEach(func() {
+				t.createServiceImport(newClusterServiceImport(namespace1, service1, serviceIP1, clusterID1, port1))
+			})
+
+			Context("and then deleted", func() {
+				Specify("GetDNSRecords should eventually deem the cluster unhealthy and return no DNS record", func() {
+					t.awaitDNSRecordsFound(namespace1, service1, clusterID1, "", false, expDNSRecord)
+
+					err := t.endpointSlices.Namespace(namespace1).Delete(context.TODO(), endpointSlice.Name, metav1.DeleteOptions{})
+					Expect(err).To(Succeed())
+
+					t.awaitDNSRecordsFound(namespace1, service1, "", "", false)
+				})
+			})
+
+			Context("and then updated to unhealthy", func() {
+				Specify("GetDNSRecords should eventually return no DNS record", func() {
+					t.awaitDNSRecordsFound(namespace1, service1, clusterID1, "", false, expDNSRecord)
+
+					err := t.endpointSlices.Namespace(namespace1).Delete(context.TODO(), endpointSlice.Name, metav1.DeleteOptions{})
+					Expect(err).To(Succeed())
+
+					t.awaitDNSRecordsFound(namespace1, service1, "", "", false)
+				})
+			})
+		})
+	})
+})