Add rqlite version to each HTTP response

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 3.3.1 (unreleased)
+- [PR #159](https://github.com/rqlite/rqlite/pull/159): All HTTP responses set X-RQLITE-VERSION.
+
 ## 3.3.0 (June 1st 2016)
 - [PR #151](https://github.com/rqlite/rqlite/pull/151): Support configurable Raft heartbeat timeout.
 - [PR #149](https://github.com/rqlite/rqlite/pull/149): Support configurable Raft snapshot thresholds.

http/service.go

@@ -193,6 +193,13 @@ func (s *Service) Close() {
 
 // ServeHTTP allows Service to serve HTTP requests.
 func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// Add version header to every response, if available.
+	if v, ok := s.BuildInfo["version"].(string); ok {
+		w.Header().Add("X-RQLITE-VERSION", v)
+	} else {
+		w.Header().Add("X-RQLITE-VERSION", "unknown")
+	}
+
 	if s.credentialStore != nil {
 		username, password, ok := r.BasicAuth()
 		if !ok || !s.credentialStore.Check(username, password) {

http/service_test.go

@@ -55,6 +55,29 @@ func Test_NewService(t *testing.T) {
 	}
 }
 
+func Test_HasVersionHeader(t *testing.T) {
+	m := &MockStore{}
+	s := New("127.0.0.1:0", m, nil)
+	if err := s.Start(); err != nil {
+		t.Fatalf("failed to start service")
+	}
+	defer s.Close()
+	s.BuildInfo = map[string]interface{}{
+		"version": "the version",
+	}
+	host := fmt.Sprintf("http://%s", s.Addr().String())
+
+	client := &http.Client{}
+	resp, err := client.Get(host + "/db/xxx")
+	if err != nil {
+		t.Fatalf("failed to make request")
+	}
+
+	if resp.Header.Get("X-RQLITE-VERSION") != "the version" {
+		t.Fatalf("build version not present in HTTP resspone header")
+	}
+}
+
 func Test_404Routes(t *testing.T) {
 	m := &MockStore{}
 	s := New("127.0.0.1:0", m, nil)