Fix CoreDNS Detection

Author: skwair

integration/coredns_test.go

@@ -32,6 +32,8 @@ func (s *CoreDNSSuite) SetUpSuite(c *check.C) {
 		{Name: "coredns/coredns:1.5.2"},
 		{Name: "coredns/coredns:1.6.3"},
 		{Name: "coredns/coredns:1.7.0"},
+		{Name: "coredns/coredns:1.8.0"},
+		{Name: "coredns/coredns:1.9.0"},
 		{Name: "giantswarm/tiny-tools:3.9"},
 	}
 

integration/testdata/traefik-mesh/controller-acl-disabled.yaml

@@ -50,6 +50,7 @@ rules:
     resources:
       - deployments
     verbs:
+      - list
       - get
       - update
   - apiGroups:

integration/testdata/traefik-mesh/controller-acl-enabled.yaml

@@ -50,6 +50,7 @@ rules:
     resources:
       - deployments
     verbs:
+      - list
       - get
       - update
   - apiGroups:

pkg/dns/dns.go

@@ -89,14 +89,30 @@ func (c *Client) CheckDNSProvider(ctx context.Context) (Provider, error) {
 func (c *Client) coreDNSMatch(ctx context.Context) (bool, error) {
 	c.logger.Debugf("Checking if CoreDNS is installed in namespace %q...", metav1.NamespaceSystem)
 
-	deployment, err := c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).Get(ctx, "coredns", metav1.GetOptions{})
-	if kerrors.IsNotFound(err) {
-		c.logger.Debug("CoreDNS deployment not found")
-		return false, nil
+	// Most Kubernetes distributions deploy CoreDNS with the following label, so look for it first.
+	opts := metav1.ListOptions{
+		LabelSelector: "kubernetes.io/name=CoreDNS",
 	}
 
+	deployments, err := c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).List(ctx, opts)
 	if err != nil {
-		return false, fmt.Errorf("unable to get CoreDNS deployment in namespace %q: %w", metav1.NamespaceSystem, err)
+		return false, fmt.Errorf("unable to list CoreDNS deployments in namespace %q: %w", metav1.NamespaceSystem, err)
+	}
+
+	var deployment *appsv1.Deployment
+	if len(deployments.Items) == 1 {
+		deployment = &deployments.Items[0]
+	} else {
+		// If we did not find CoreDNS using the annotation (e.g.: with kubeadm), fall back to matching the name of the deployment.
+		deployment, err = c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).Get(ctx, "coredns", metav1.GetOptions{})
+		if kerrors.IsNotFound(err) {
+			c.logger.Debug("CoreDNS deployment not found")
+			return false, nil
+		}
+
+		if err != nil {
+			return false, fmt.Errorf("unable to get CoreDNS deployment in namespace %q: %w", metav1.NamespaceSystem, err)
+		}
 	}
 
 	version, err := c.getCoreDNSVersion(deployment)

pkg/dns/dns_test.go

@@ -26,6 +26,12 @@ func TestCheckDNSProvider(t *testing.T) {
 			expProvider: CoreDNS,
 			expErr:      false,
 		},
+		{
+			desc:        "CoreDNS supported version using label",
+			mockFile:    "checkdnsprovider_coredns_using_label.yaml",
+			expProvider: CoreDNS,
+			expErr:      false,
+		},
 		{
 			desc:        "CoreDNS supported version with suffix",
 			mockFile:    "checkdnsprovider_supported_version_suffix.yaml",

pkg/dns/testdata/checkdnsprovider_coredns_using_label.yaml

@@ -0,0 +1,15 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: rke2-coredns-rke2-coredns
+  namespace: kube-system
+  labels:
+    kubernetes.io/name: CoreDNS
+spec:
+  template:
+    spec:
+      containers:
+        - name: coredns
+          image: image-registry.dkr.ecr.eu-west-1.amazonaws.com/eks/coredns:v1.8.4
+        - name: titi
+          image: titi/toto:latest