CORS-4137: add CoreDNS upstream resolver config for dual-stack clusters

pkg/asset/manifests/coredns.go

@@ -0,0 +1,115 @@
+package manifests
+
+import (
+	"context"
+	"fmt"
+	"path"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"sigs.k8s.io/yaml"
+
+	operatorv1 "github.com/openshift/api/operator/v1"
+	"github.com/openshift/installer/pkg/asset"
+	"github.com/openshift/installer/pkg/asset/installconfig"
+	awstypes "github.com/openshift/installer/pkg/types/aws"
+	"github.com/openshift/installer/pkg/types/dns"
+)
+
+var (
+	coreDNSCfgFilename = path.Join(manifestDir, "coredns-02-config.yml")
+)
+
+// CoreDNS generates the files to configure CoreDNS component, which provides a name resolution service
+// for pods and services in the cluster.
+type CoreDNS struct {
+	FileList []*asset.File
+}
+
+var _ asset.WritableAsset = (*CoreDNS)(nil)
+
+// Name returns a human friendly name for the asset.
+func (*CoreDNS) Name() string {
+	return "CoreDNS Config"
+}
+
+// Dependencies returns all of the dependencies directly needed to generate
+// the asset.
+func (*CoreDNS) Dependencies() []asset.Asset {
+	return []asset.Asset{
+		&installconfig.InstallConfig{},
+	}
+}
+
+// Generate generates the CoreDNS config and its CRD.
+func (d *CoreDNS) Generate(ctx context.Context, dependencies asset.Parents) error {
+	installConfig := &installconfig.InstallConfig{}
+	dependencies.Get(installConfig)
+
+	var controllerConfig *operatorv1.DNS
+
+	switch installConfig.Config.Platform.Name() {
+	case awstypes.Name:
+		// We don't configure coreDNS here when UserProvisionedDNS is enabled
+		if installConfig.Config.AWS.UserProvisionedDNS == dns.UserProvisionedDNSEnabled {
+			return nil
+		}
+
+		if installConfig.Config.AWS.IPFamily.DualStackEnabled() {
+			// By default, in dualstack subnets, the resolver config file on instances only define the IPv4 DNS resolver.
+			// For dualstack, we need to also allow the IPv6 DNS resolver "fd00:ec2::253"
+			// See: https://docs.aws.amazon.com/whitepapers/latest/ipv6-on-aws/supporting-amazon-vpc-services.html#route-53-dns-resolver
+			controllerConfig = &operatorv1.DNS{
+				TypeMeta: metav1.TypeMeta{
+					APIVersion: operatorv1.SchemeGroupVersion.String(),
+					Kind:       "DNS",
+				},
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "default",
+					// not namespaced
+				},
+				Spec: operatorv1.DNSSpec{
+					UpstreamResolvers: operatorv1.UpstreamResolvers{
+						Policy: operatorv1.SequentialForwardingPolicy,
+						Upstreams: []operatorv1.Upstream{
+							{
+								Type: operatorv1.SystemResolveConfType,
+							},
+							{
+
+								Type:    operatorv1.NetworkResolverType,
+								Address: "fd00:ec2::253",
+							},
+						},
+					},
+				},
+			}
+		}
+	default:
+	}
+
+	if controllerConfig != nil {
+		configData, err := yaml.Marshal(controllerConfig)
+		if err != nil {
+			return fmt.Errorf("failed to create %s manifests from InstallConfig: %w", d.Name(), err)
+		}
+
+		d.FileList = []*asset.File{
+			{
+				Filename: coreDNSCfgFilename,
+				Data:     configData,
+			},
+		}
+	}
+
+	return nil
+}
+
+// Files returns the files generated by the asset.
+func (d *CoreDNS) Files() []*asset.File {
+	return d.FileList
+}
+
+// Load loads the already-rendered files back from disk.
+func (d *CoreDNS) Load(f asset.FileFetcher) (bool, error) {
+	return false, nil
+}

pkg/asset/manifests/operators.go

@@ -68,6 +68,7 @@ func (m *Manifests) Dependencies() []asset.Asset {
 		&manifests.MCO{},
 		&Ingress{},
 		&DNS{},
+		&CoreDNS{},
 		&Infrastructure{},
 		&Networking{},
 		&Proxy{},
@@ -97,6 +98,7 @@ func (m *Manifests) Dependencies() []asset.Asset {
 func (m *Manifests) Generate(_ context.Context, dependencies asset.Parents) error {
 	ingress := &Ingress{}
 	dns := &DNS{}
+	coreDNS := &CoreDNS{}
 	network := &Networking{}
 	infra := &Infrastructure{}
 	installConfig := &installconfig.InstallConfig{}
@@ -108,7 +110,7 @@ func (m *Manifests) Generate(_ context.Context, dependencies asset.Parents) erro
 	mcoCfgTemplate := &manifests.MCO{}
 	bmcVerifyCAConfigMap := &BMCVerifyCAConfigMap{}
 
-	dependencies.Get(installConfig, ingress, dns, network, infra, proxy, scheduler, imageContentSourcePolicy, imageDigestMirrorSet, clusterCSIDriverConfig, mcoCfgTemplate, bmcVerifyCAConfigMap)
+	dependencies.Get(installConfig, ingress, dns, coreDNS, network, infra, proxy, scheduler, imageContentSourcePolicy, imageDigestMirrorSet, clusterCSIDriverConfig, mcoCfgTemplate, bmcVerifyCAConfigMap)
 
 	redactedConfig, err := redactedInstallConfig(*installConfig.Config)
 	if err != nil {
@@ -139,6 +141,7 @@ func (m *Manifests) Generate(_ context.Context, dependencies asset.Parents) erro
 
 	m.FileList = append(m.FileList, ingress.Files()...)
 	m.FileList = append(m.FileList, dns.Files()...)
+	m.FileList = append(m.FileList, coreDNS.Files()...)
 	m.FileList = append(m.FileList, network.Files()...)
 	m.FileList = append(m.FileList, infra.Files()...)
 	m.FileList = append(m.FileList, proxy.Files()...)