validate localities on agent configs and registration endpoints

agent/config/builder.go

@@ -1290,6 +1290,10 @@ func (b *builder) validate(rt RuntimeConfig) error {
 			"1 and 63 bytes.", rt.NodeName)
 	}
 
+	if err := rt.StructLocality().Validate(); err != nil {
+		return fmt.Errorf("locality is invalid: %s", err)
+	}
+
 	if ipaddr.IsAny(rt.AdvertiseAddrLAN.IP) {
 		return fmt.Errorf("Advertise address cannot be 0.0.0.0, :: or [::]")
 	}

agent/config/runtime_test.go

@@ -1036,6 +1036,13 @@ func TestLoad_IntegrationWithFlags(t *testing.T) {
 			},
 		},
 	})
+	run(t, testCase{
+		desc:        "locality invalid",
+		args:        []string{`-data-dir=` + dataDir},
+		json:        []string{`{"locality": {"zone": "us-west-1a"}}`},
+		hcl:         []string{`locality { zone = "us-west-1a" }`},
+		expectedErr: "locality is invalid: zone cannot be set without region",
+	})
 	run(t, testCase{
 		desc: "client addr and ports == 0",
 		args: []string{`-data-dir=` + dataDir},

agent/structs/structs.go

@@ -1480,6 +1480,10 @@ func (s *NodeService) IsGateway() bool {
 func (s *NodeService) Validate() error {
 	var result error
 
+	if err := s.Locality.Validate(); err != nil {
+		result = multierror.Append(result, err)
+	}
+
 	if s.Kind == ServiceKindConnectProxy {
 		if s.Port == 0 && s.SocketPath == "" {
 			result = multierror.Append(result, fmt.Errorf("Port or SocketPath must be set for a %s", s.Kind))
@@ -3111,3 +3115,15 @@ func (l *Locality) GetRegion() string {
 	}
 	return l.Region
 }
+
+func (l *Locality) Validate() error {
+	if l == nil {
+		return nil
+	}
+
+	if l.Region == "" && l.Zone != "" {
+		return fmt.Errorf("zone cannot be set without region")
+	}
+
+	return nil
+}

agent/structs/structs_test.go

@@ -592,6 +592,43 @@ func TestStructs_ServiceNode_Conversions(t *testing.T) {
 	}
 }
 
+func TestStructs_Locality_Validate(t *testing.T) {
+	type testCase struct {
+		locality *Locality
+		err      string
+	}
+	cases := map[string]testCase{
+		"nil": {
+			nil,
+			"",
+		},
+		"region only": {
+			&Locality{Region: "us-west-1"},
+			"",
+		},
+		"region and zone": {
+			&Locality{Region: "us-west-1", Zone: "us-west-1a"},
+			"",
+		},
+		"zone only": {
+			&Locality{Zone: "us-west-1a"},
+			"zone cannot be set without region",
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			err := tc.locality.Validate()
+			if tc.err == "" {
+				require.NoError(t, err)
+			} else {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tc.err)
+			}
+		})
+	}
+}
+
 func TestStructs_NodeService_ValidateMeshGateway(t *testing.T) {
 	type testCase struct {
 		Modify func(*NodeService)
@@ -1152,6 +1189,13 @@ func TestStructs_NodeService_ValidateConnectProxy(t *testing.T) {
 			},
 			"",
 		},
+		{
+			"connect-proxy: invalid locality",
+			func(x *NodeService) {
+				x.Locality = &Locality{Zone: "bad"}
+			},
+			"zone cannot be set without region",
+		},
 	}
 
 	for _, tc := range cases {