etcdhttp: return 409 instead of 412 when there is a conflict when adding a member

etcdserver/etcdhttp/client.go

@@ -189,7 +189,7 @@ func (h *membersHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		err = h.server.AddMember(ctx, *m)
 		switch {
 		case err == etcdserver.ErrIDExists || err == etcdserver.ErrPeerURLexists:
-			writeError(w, httptypes.NewHTTPError(http.StatusPreconditionFailed, err.Error()))
+			writeError(w, httptypes.NewHTTPError(http.StatusConflict, err.Error()))
 			return
 		case err != nil:
 			log.Printf("etcdhttp: error adding node %s: %v", m.ID, err)

etcdserver/etcdhttp/client_test.go

@@ -773,6 +773,34 @@ func TestServeMembersFail(t *testing.T) {
 
 			http.StatusInternalServerError,
 		},
+		{
+			// etcdserver.AddMember error
+			&http.Request{
+				URL:    mustNewURL(t, membersPrefix),
+				Method: "POST",
+				Body:   ioutil.NopCloser(strings.NewReader(`{"PeerURLs": ["http://127.0.0.1:1"]}`)),
+				Header: map[string][]string{"Content-Type": []string{"application/json"}},
+			},
+			&errServer{
+				etcdserver.ErrIDExists,
+			},
+
+			http.StatusConflict,
+		},
+		{
+			// etcdserver.AddMember error
+			&http.Request{
+				URL:    mustNewURL(t, membersPrefix),
+				Method: "POST",
+				Body:   ioutil.NopCloser(strings.NewReader(`{"PeerURLs": ["http://127.0.0.1:1"]}`)),
+				Header: map[string][]string{"Content-Type": []string{"application/json"}},
+			},
+			&errServer{
+				etcdserver.ErrPeerURLexists,
+			},
+
+			http.StatusConflict,
+		},
 		{
 			// etcdserver.RemoveMember error with arbitrary server error
 			&http.Request{