[management] Force routing-peer DNS resolution for reverse-proxy domain targets (#6872)

management/server/types/account.go

@@ -1517,6 +1517,54 @@ func (a *Account) GetResourceRoutersMap() map[string]map[string]*routerTypes.Net
 	return routers
 }
 
+// forcesRoutingPeerDNSResolution reports whether the given peer must run
+// routing-peer DNS resolution regardless of the account-global
+// RoutingPeerDNSResolutionEnabled setting. It returns true when the peer is a
+// router for a domain network resource that is targeted by an enabled
+// reverse-proxy service, so the peer's DNS forwarder starts and can resolve
+// the target for the embedded proxy peers. Embedded proxy peers themselves are
+// handled at PeerConfig build time.
+func (a *Account) forcesRoutingPeerDNSResolution(peerID string, routers map[string]map[string]*routerTypes.NetworkRouter) bool {
+	targeted := a.proxyTargetedDomainResourceIDs()
+	if len(targeted) == 0 {
+		return false
+	}
+
+	for _, resource := range a.NetworkResources {
+		if resource == nil || !resource.Enabled || resource.Type != resourceTypes.Domain {
+			continue
+		}
+		if _, ok := targeted[resource.ID]; !ok {
+			continue
+		}
+		if _, isRouter := routers[resource.NetworkID][peerID]; isRouter {
+			return true
+		}
+	}
+
+	return false
+}
+
+// proxyTargetedDomainResourceIDs returns the set of domain network resource IDs
+// targeted by an enabled, non-terminated reverse-proxy service.
+func (a *Account) proxyTargetedDomainResourceIDs() map[string]struct{} {
+	ids := make(map[string]struct{})
+	for _, svc := range a.Services {
+		if svc == nil || !svc.Enabled || svc.Terminated {
+			continue
+		}
+		for _, target := range svc.Targets {
+			if target == nil || !target.Enabled {
+				continue
+			}
+			if target.TargetType == service.TargetTypeDomain {
+				ids[target.TargetId] = struct{}{}
+			}
+		}
+	}
+	return ids
+}
+
 // getPoliciesSourcePeers collects all unique peers from the source groups defined in the given policies.
 func getPoliciesSourcePeers(policies []*Policy, groups map[string]*Group) map[string]struct{} {
 	sourcePeers := make(map[string]struct{})

management/server/types/account_components.go

@@ -140,6 +140,8 @@ func (a *Account) GetPeerNetworkMapComponents(
 		RouterPeers:               make(map[string]*ComponentPeer),
 		NetworkXIDToPublicID:      make(map[string]string, len(a.Networks)),
 		PostureCheckXIDToPublicID: make(map[string]string, len(a.PostureChecks)),
+
+		ForceRoutingPeerDNSResolution: a.forcesRoutingPeerDNSResolution(peerID, routers),
 	}
 	for _, n := range a.Networks {
 		if n != nil {

management/server/types/account_test.go

@@ -1751,3 +1751,71 @@ func hasPrivateAccessPolicy(account *Account, serviceID string) bool {
 	}
 	return false
 }
+
+func TestForcesRoutingPeerDNSResolution(t *testing.T) {
+	buildAccountRes := func(serviceEnabled, targetEnabled, resourceEnabled bool, targetType service.TargetType, resType resourceTypes.NetworkResourceType) *Account {
+		return &Account{
+			Id: "accountID",
+			Groups: map[string]*Group{
+				"router-group": {ID: "router-group", Peers: []string{"router-peer-grp"}},
+			},
+			NetworkRouters: []*routerTypes.NetworkRouter{
+				{ID: "r1", NetworkID: "net-1", AccountID: "accountID", Peer: "router-peer", Enabled: true},
+				{ID: "r2", NetworkID: "net-1", AccountID: "accountID", PeerGroups: []string{"router-group"}, Enabled: true},
+			},
+			NetworkResources: []*resourceTypes.NetworkResource{
+				{ID: "res-domain", AccountID: "accountID", NetworkID: "net-1", Type: resType, Domain: "example.org", Enabled: resourceEnabled},
+			},
+			Services: []*service.Service{
+				{
+					ID: "svc-1", AccountID: "accountID", Enabled: serviceEnabled,
+					Targets: []*service.Target{
+						{TargetId: "res-domain", TargetType: targetType, Enabled: targetEnabled},
+					},
+				},
+			},
+		}
+	}
+
+	buildAccount := func(serviceEnabled, targetEnabled, resourceEnabled bool, targetType service.TargetType) *Account {
+		return buildAccountRes(serviceEnabled, targetEnabled, resourceEnabled, targetType, resourceTypes.Domain)
+	}
+
+	t.Run("router peer for RP-targeted domain resource is forced", func(t *testing.T) {
+		account := buildAccount(true, true, true, service.TargetTypeDomain)
+		routers := account.GetResourceRoutersMap()
+		assert.True(t, account.forcesRoutingPeerDNSResolution("router-peer", routers), "direct router peer should be forced")
+		assert.True(t, account.forcesRoutingPeerDNSResolution("router-peer-grp", routers), "group-member router peer should be forced")
+	})
+
+	t.Run("non-router peer is not forced", func(t *testing.T) {
+		account := buildAccount(true, true, true, service.TargetTypeDomain)
+		assert.False(t, account.forcesRoutingPeerDNSResolution("other-peer", account.GetResourceRoutersMap()))
+	})
+
+	t.Run("not forced when service disabled", func(t *testing.T) {
+		account := buildAccount(false, true, true, service.TargetTypeDomain)
+		assert.False(t, account.forcesRoutingPeerDNSResolution("router-peer", account.GetResourceRoutersMap()))
+	})
+
+	t.Run("not forced when target disabled", func(t *testing.T) {
+		account := buildAccount(true, false, true, service.TargetTypeDomain)
+		assert.False(t, account.forcesRoutingPeerDNSResolution("router-peer", account.GetResourceRoutersMap()))
+	})
+
+	t.Run("not forced when resource disabled", func(t *testing.T) {
+		account := buildAccount(true, true, false, service.TargetTypeDomain)
+		assert.False(t, account.forcesRoutingPeerDNSResolution("router-peer", account.GetResourceRoutersMap()))
+	})
+
+	t.Run("not forced for non-domain target type", func(t *testing.T) {
+		account := buildAccount(true, true, true, service.TargetTypePeer)
+		assert.False(t, account.forcesRoutingPeerDNSResolution("router-peer", account.GetResourceRoutersMap()))
+	})
+
+	t.Run("not forced when targeted resource is not a domain", func(t *testing.T) {
+		account := buildAccountRes(true, true, true, service.TargetTypeDomain, resourceTypes.Host)
+		assert.False(t, account.forcesRoutingPeerDNSResolution("router-peer", account.GetResourceRoutersMap()),
+			"a domain target pointing at a non-domain resource must not force resolution")
+	})
+}