Adds an `X-Consul-Translate-Addresses` to signal translation is enabled.

api/api.go

@@ -80,6 +80,9 @@ type QueryMeta struct {
 
 	// How long did the request take
 	RequestTime time.Duration
+
+	// Is address translation enabled for HTTP responses on this agent
+	AddressTranslationEnabled bool
 }
 
 // WriteMeta is used to return meta data about a write
@@ -542,6 +545,15 @@ func parseQueryMeta(resp *http.Response, q *QueryMeta) error {
 	default:
 		q.KnownLeader = false
 	}
+
+	// Parse X-Consul-Translate-Addresses
+	switch header.Get("X-Consul-Translate-Addresses") {
+	case "true":
+		q.AddressTranslationEnabled = true
+	default:
+		q.AddressTranslationEnabled = false
+	}
+
 	return nil
 }
 

api/api_test.go

@@ -306,6 +306,7 @@ func TestParseQueryMeta(t *testing.T) {
 	resp.Header.Set("X-Consul-Index", "12345")
 	resp.Header.Set("X-Consul-LastContact", "80")
 	resp.Header.Set("X-Consul-KnownLeader", "true")
+	resp.Header.Set("X-Consul-Translate-Addresses", "true")
 
 	qm := &QueryMeta{}
 	if err := parseQueryMeta(resp, qm); err != nil {
@@ -321,6 +322,9 @@ func TestParseQueryMeta(t *testing.T) {
 	if !qm.KnownLeader {
 		t.Fatalf("Bad: %v", qm)
 	}
+	if !qm.AddressTranslationEnabled {
+		t.Fatalf("Bad: %v", qm)
+	}
 }
 
 func TestAPI_UnixSocket(t *testing.T) {

command/agent/http.go

@@ -329,6 +329,7 @@ func (s *HTTPServer) registerHandlers(enableDebug bool) {
 func (s *HTTPServer) wrap(handler func(resp http.ResponseWriter, req *http.Request) (interface{}, error)) func(resp http.ResponseWriter, req *http.Request) {
 	f := func(resp http.ResponseWriter, req *http.Request) {
 		setHeaders(resp, s.agent.config.HTTPAPIResponseHeaders)
+		setTranslateAddr(resp, s.agent.config.TranslateWanAddrs)
 
 		// Obfuscate any tokens from appearing in the logs
 		formVals, err := url.ParseQuery(req.URL.RawQuery)
@@ -373,6 +374,7 @@ func (s *HTTPServer) wrap(handler func(resp http.ResponseWriter, req *http.Reque
 			if strings.Contains(errMsg, "Permission denied") || strings.Contains(errMsg, "ACL not found") {
 				code = http.StatusForbidden // 403
 			}
+
 			resp.WriteHeader(code)
 			resp.Write([]byte(err.Error()))
 			return
@@ -452,6 +454,14 @@ func decodeBody(req *http.Request, out interface{}, cb func(interface{}) error)
 	return mapstructure.Decode(raw, out)
 }
 
+// setTranslateAddr is used to set the address translation header. This is only
+// present if the feature is active.
+func setTranslateAddr(resp http.ResponseWriter, active bool) {
+	if active {
+		resp.Header().Set("X-Consul-Translate-Addresses", "true")
+	}
+}
+
 // setIndex is used to set the index response header
 func setIndex(resp http.ResponseWriter, index uint64) {
 	resp.Header().Set("X-Consul-Index", strconv.FormatUint(index, 10))

command/agent/http_test.go

@@ -223,6 +223,51 @@ func TestSetMeta(t *testing.T) {
 	}
 }
 
+func TestHTTPAPI_TranslateAddrHeader(t *testing.T) {
+	// Header should not be present if address translation is off.
+	{
+		dir, srv := makeHTTPServer(t)
+		defer os.RemoveAll(dir)
+		defer srv.Shutdown()
+		defer srv.agent.Shutdown()
+
+		resp := httptest.NewRecorder()
+		handler := func(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+			return nil, nil
+		}
+
+		req, _ := http.NewRequest("GET", "/v1/agent/self", nil)
+		srv.wrap(handler)(resp, req)
+
+		translate := resp.Header().Get("X-Consul-Translate-Addresses")
+		if translate != "" {
+			t.Fatalf("bad: expected %q, got %q", "", translate)
+		}
+	}
+
+	// Header should be set to true if it's turned on.
+	{
+		dir, srv := makeHTTPServer(t)
+		srv.agent.config.TranslateWanAddrs = true
+		defer os.RemoveAll(dir)
+		defer srv.Shutdown()
+		defer srv.agent.Shutdown()
+
+		resp := httptest.NewRecorder()
+		handler := func(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+			return nil, nil
+		}
+
+		req, _ := http.NewRequest("GET", "/v1/agent/self", nil)
+		srv.wrap(handler)(resp, req)
+
+		translate := resp.Header().Get("X-Consul-Translate-Addresses")
+		if translate != "true" {
+			t.Fatalf("bad: expected %q, got %q", "true", translate)
+		}
+	}
+}
+
 func TestHTTPAPIResponseHeaders(t *testing.T) {
 	dir, srv := makeHTTPServer(t)
 	srv.agent.config.HTTPAPIResponseHeaders = map[string]string{

website/source/docs/agent/http.html.markdown

@@ -96,3 +96,12 @@ configuration option. However, the token can also be specified per-request
 by using the `X-Consul-Token` request header or the `token` querystring
 parameter. The request header takes precedence over the default token, and
 the querystring parameter takes precedence over everything.
+
+
+## <a id="translate_header"></a>Translated Addresses
+
+Consul 0.7 added the ability to translate addresses in HTTP response based on the configuration
+setting for [`translate_wan_addrs`](/docs/agent/options.html#translate_wan_addrs). In order to
+allow clients to know if address translation is in effect, the `X-Consul-Translate-Addresses`
+header will be added if translation is enabled, and will have a value of `true`. If translation
+is not enabled then this header will not be present.

website/source/docs/agent/options.html.markdown

@@ -756,9 +756,14 @@ Consul will not enable TLS for the HTTP API unless the `https` port has been ass
   default.
   <br>
   <br>
-  Starting in Consul 0.7 and later, node addresses in responses to the following HTTP endpoints will
-  prefer a node's configured <a href="#_advertise-wan">WAN address</a> when querying for a node in a
-  remote datacenter:
+  Starting in Consul 0.7 and later, node addresses in responses to HTTP requests will also prefer a
+  node's configured <a href="#_advertise-wan">WAN address</a> when querying for a node in a remote
+  datacenter. An [`X-Consul-Translate-Addresses`](/docs/agent/http.html#translate_header) header
+  will be present on all responses when translation is enabled to help clients know that the addresses
+  may be translated. The `TaggedAddresses` field in responses also have a `lan` address for clients that
+  need knowledge of that address, regardless of translation.
+  <br>
+  <br>The following endpoints translate addresses:
   <br>
   * [`/v1/catalog/nodes`](/docs/agent/http/catalog.html#catalog_nodes)
   * [`/v1/catalog/node/<node>`](/docs/agent/http/catalog.html#catalog_node)