fix: add label to skip coredns injection at cluster creation and start

add new LabelClusterCoreDNSDisabled label to track CoreDNS disabled
state, such that CoreDNS injection is skipped at cluster creation and
start

fixes #1610

Author: maltelehmann

pkg/client/cluster.go

@@ -1114,13 +1114,11 @@ func ClusterStart(ctx context.Context, runtime k3drt.Runtime, cluster *k3d.Clust
 
 					// get the first server in the list and run action on it once it's ready for it
 					for _, n := range servers {
-						// do not try to run the action, if CoreDNS is disabled on K3s level
-						for _, flag := range n.Args {
-							if strings.HasPrefix(flag, "--disable") && strings.Contains(flag, "coredns") {
-								l.Log().Debugf("CoreDNS disabled in K3s via flag `%s`. Not trying to use it.", flag)
-								return nil
-							}
+						if coreDNSDisabledLabel, exists := n.RuntimeLabels[k3d.LabelClusterCoreDNSDisabled]; exists && coreDNSDisabledLabel == "true" {
+							l.Log().Debugf("CoreDNS disabled via cluster label. Not trying to use it.")
+							return nil
 						}
+
 						ts, err := time.Parse("2006-01-02T15:04:05.999999999Z", n.State.Started)
 						if err != nil {
 							return err

pkg/config/transform.go

@@ -269,6 +269,7 @@ func TransformSimpleToClusterConfig(ctx context.Context, runtime runtimes.Runtim
 	}
 
 	// -> ARGS
+	coreDNSDisabled := false
 	for _, argWithNodeFilters := range simpleConfig.Options.K3sOptions.ExtraArgs {
 		if len(argWithNodeFilters.NodeFilters) == 0 && nodeCount > 1 {
 			return nil, fmt.Errorf("K3sExtraArg '%s' lacks a node filter, but there's more than one node", argWithNodeFilters.Arg)
@@ -282,6 +283,11 @@ func TransformSimpleToClusterConfig(ctx context.Context, runtime runtimes.Runtim
 		for _, node := range nodes {
 			node.Args = append(node.Args, argWithNodeFilters.Arg)
 		}
+
+		if strings.HasPrefix(argWithNodeFilters.Arg, "--disable") && strings.Contains(argWithNodeFilters.Arg, "coredns") {
+			coreDNSDisabled = true
+		}
+
 	}
 
 	/**************************
@@ -306,6 +312,10 @@ func TransformSimpleToClusterConfig(ctx context.Context, runtime runtimes.Runtim
 		clusterCreateOpts.GlobalLabels[k] = v
 	}
 
+	if coreDNSDisabled {
+		clusterCreateOpts.GlobalLabels[k3d.LabelClusterCoreDNSDisabled] = "true"
+	}
+
 	/*
 	 * Registries
 	 */

pkg/types/types.go

@@ -86,6 +86,7 @@ const (
 	LabelNetworkID               string = "k3d.cluster.network.id"
 	LabelNetworkIPRange          string = "k3d.cluster.network.iprange"
 	LabelClusterStartHostAliases string = "k3d.cluster.start.hostaliases"
+	LabelClusterCoreDNSDisabled  string = "k3d.cluster.coredns.disabled"
 	LabelRole                    string = "k3d.role"
 	LabelServerAPIPort           string = "k3d.server.api.port"
 	LabelServerAPIHost           string = "k3d.server.api.host"