Backport of Use strict DNS for mesh gateways with hostnames into rele…

…ase/1.16.x (#19395) Use strict DNS for mesh gateways with hostnames Co-authored-by: Andrew Stucki <[email protected]>
hashicorp · Oct 27, 2023 · 0fd8cdb · 0fd8cdb
1 parent 54e1c9e
commit 0fd8cdb
Show file tree

Hide file tree

Showing 3 changed files with 12 additions and 6 deletions.
diff --git a/.changelog/19268.txt b/.changelog/19268.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+Mesh Gateways: Fix a bug where replicated and peered mesh gateways with hostname-based WAN addresses fail to initialize.
+```
diff --git a/agent/xds/clusters.go b/agent/xds/clusters.go
@@ -638,10 +638,13 @@ func (s *ResourceGenerator) makePeerServerClusters(cfgSnap *proxycfg.ConfigSnaps
 
 		var cluster *envoy_cluster_v3.Cluster
 		if servers.UseCDS {
+			// we use strict DNS here since multiple gateways with hostnames
+			// would result in an invalid cluster due to logical DNS requiring
+			// only a single host
 			cluster = s.makeExternalHostnameCluster(cfgSnap, clusterOpts{
 				name:      name,
 				addresses: servers.Addresses,
-			})
+			}, envoy_cluster_v3.Cluster_STRICT_DNS)
 		} else {
 			cluster = s.makeGatewayCluster(cfgSnap, clusterOpts{
 				name: name,
@@ -860,7 +863,7 @@ func (s *ResourceGenerator) makeDestinationClusters(cfgSnap *proxycfg.ConfigSnap
 			if structs.IsIP(address) {
 				cluster = s.makeExternalIPCluster(cfgSnap, opts)
 			} else {
-				cluster = s.makeExternalHostnameCluster(cfgSnap, opts)
+				cluster = s.makeExternalHostnameCluster(cfgSnap, opts, envoy_cluster_v3.Cluster_LOGICAL_DNS)
 			}
 			if err := s.injectGatewayDestinationAddons(cfgSnap, cluster, svcName); err != nil {
 				return nil, err
@@ -1885,8 +1888,8 @@ func (s *ResourceGenerator) makeExternalIPCluster(snap *proxycfg.ConfigSnapshot,
 }
 
 // makeExternalHostnameCluster creates an Envoy cluster for hostname endpoints that will be resolved with DNS
-// This is used by both terminating gateways for Destinations, and Mesh Gateways for peering control plane traffice
-func (s *ResourceGenerator) makeExternalHostnameCluster(snap *proxycfg.ConfigSnapshot, opts clusterOpts) *envoy_cluster_v3.Cluster {
+// This is used by both terminating gateways for Destinations, and Mesh Gateways for peering control plane traffic
+func (s *ResourceGenerator) makeExternalHostnameCluster(snap *proxycfg.ConfigSnapshot, opts clusterOpts, discoveryType envoy_cluster_v3.Cluster_DiscoveryType) *envoy_cluster_v3.Cluster {
 	cfg, err := ParseGatewayConfig(snap.Proxy.Config)
 	if err != nil {
 		// Don't hard fail on a config typo, just warn. The parse func returns
@@ -1901,7 +1904,7 @@ func (s *ResourceGenerator) makeExternalHostnameCluster(snap *proxycfg.ConfigSna
 
 		// Having an empty config enables outlier detection with default config.
 		OutlierDetection:     &envoy_cluster_v3.OutlierDetection{},
-		ClusterDiscoveryType: &envoy_cluster_v3.Cluster_Type{Type: envoy_cluster_v3.Cluster_LOGICAL_DNS},
+		ClusterDiscoveryType: &envoy_cluster_v3.Cluster_Type{Type: discoveryType},
 		DnsLookupFamily:      envoy_cluster_v3.Cluster_V4_ONLY,
 	}
 

diff --git a/...t/xds/testdata/clusters/mesh-gateway-with-peer-through-mesh-gateway-enabled.latest.golden b/...t/xds/testdata/clusters/mesh-gateway-with-peer-through-mesh-gateway-enabled.latest.golden
@@ -30,7 +30,7 @@
     {
       "@type": "type.googleapis.com/envoy.config.cluster.v3.Cluster",
       "name": "server.dc3.peering.f622dc37-7238-4485-ab58-0f53864a9ae5",
-      "type": "LOGICAL_DNS",
+      "type": "STRICT_DNS",
       "connectTimeout": "5s",
       "loadAssignment": {
         "clusterName": "server.dc3.peering.f622dc37-7238-4485-ab58-0f53864a9ae5",