From bb89c9922046e1f63301076971c7ad715ade6534 Mon Sep 17 00:00:00 2001
From: Martin Weindel <martin.weindel@sap.com>
Date: Mon, 31 Oct 2022 13:17:28 +0100
Subject: [PATCH] allow more cname targets (25 instead of 11); remove obsolete
 code from changemodel

---
 pkg/dns/dnsset.go               |  1 -
 pkg/dns/provider/changemodel.go | 28 ++--------------------------
 pkg/dns/provider/entry.go       |  7 +++++--
 3 files changed, 7 insertions(+), 29 deletions(-)

diff --git a/pkg/dns/dnsset.go b/pkg/dns/dnsset.go
index d07a81091..e4a732207 100644
--- a/pkg/dns/dnsset.go
+++ b/pkg/dns/dnsset.go
@@ -119,7 +119,6 @@ func (dnssets DNSSets) GetOwners() utils.StringSet {
 const (
 	ATTR_OWNER  = "owner"
 	ATTR_PREFIX = "prefix"
-	ATTR_CNAMES = "cnames"
 	ATTR_KIND   = "kind"
 
 	ATTR_TIMESTAMP = "ts"
diff --git a/pkg/dns/provider/changemodel.go b/pkg/dns/provider/changemodel.go
index cee2adcdc..ead786b9f 100644
--- a/pkg/dns/provider/changemodel.go
+++ b/pkg/dns/provider/changemodel.go
@@ -19,8 +19,6 @@ package provider
 import (
 	"fmt"
 	"reflect"
-	"sort"
-	"strings"
 	"time"
 
 	api "github.com/gardener/external-dns-management/pkg/apis/dns/v1alpha1"
@@ -522,35 +520,13 @@ func (this *ChangeModel) ApplySpec(set *dns.DNSSet, base *dns.DNSSet, provider D
 	}
 
 	targetsets := set.Sets
-	cnames := []string{}
 	for _, t := range spec.Targets() {
 		// use status calculated in entry
 		ttl := t.GetTTL()
-		if t.GetRecordType() == dns.RS_CNAME && len(spec.Targets()) > 1 {
-			cnames = append(cnames, t.GetHostName())
-			ipv4addrs, ipv6addrs, err := lookupHosts(t.GetHostName())
-			if err == nil {
-				for _, addr := range ipv4addrs {
-					AddRecord(targetsets, dns.RS_A, addr, ttl)
-				}
-				for _, addr := range ipv6addrs {
-					AddRecord(targetsets, dns.RS_AAAA, addr, ttl)
-				}
-			} else {
-				this.Errorf("cannot lookup '%s': %s", t.GetHostName(), err)
-			}
-			this.Debugf("mapping target '%s' to A records: %s or AAAA records: %s",
-				t.GetHostName(), strings.Join(ipv4addrs, ","), strings.Join(ipv6addrs, ","))
-		} else {
-			t = provider.MapTarget(t)
-			AddRecord(targetsets, t.GetRecordType(), t.GetHostName(), ttl)
-		}
+		t = provider.MapTarget(t)
+		AddRecord(targetsets, t.GetRecordType(), t.GetHostName(), ttl)
 	}
 	set.Sets = targetsets
-	if len(cnames) > 0 && this.Owns(set) {
-		sort.Strings(cnames)
-		set.SetMetaAttr(dns.ATTR_CNAMES, strings.Join(cnames, ","))
-	}
 	return set
 }
 
diff --git a/pkg/dns/provider/entry.go b/pkg/dns/provider/entry.go
index 99296a403..0710e45bb 100644
--- a/pkg/dns/provider/entry.go
+++ b/pkg/dns/provider/entry.go
@@ -43,6 +43,9 @@ import (
 
 const MSG_PRESERVED = "errorneous entry preserved in provider"
 
+// maxCNAMETargets is the maximum number of CNAME targets. It is restricted, as it needs regular DNS lookups.
+const maxCNAMETargets = 25
+
 type EntryPremise struct {
 	ptypes   utils.StringSet
 	ptype    string
@@ -774,8 +777,8 @@ func normalizeTargets(logger logger.LogContext, object dnsutils.DNSSpecification
 	}
 
 	result := make(Targets, 0, len(targets))
-	if len(targets) > 11 {
-		w := fmt.Sprintf("too many CNAME targets: %d", len(targets))
+	if len(targets) > maxCNAMETargets {
+		w := fmt.Sprintf("too many CNAME targets: %d (maximum allowed: %d)", len(targets), maxCNAMETargets)
 		logger.Warn(w)
 		object.Event(corev1.EventTypeWarning, "dnslookup restriction", w)
 		return result, true, false