/healthz should not report ok when vttablet is not connected to mysql

go/vt/vttablet/tabletserver/tabletserver.go

@@ -1534,19 +1534,21 @@ var okMessage = []byte("ok\n")
 // Health check
 // Returns ok if we are in the desired serving state
 func (tsv *TabletServer) registerHealthzHealthHandler() {
-	tsv.exporter.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
-		if err := acl.CheckAccessHTTP(r, acl.MONITORING); err != nil {
-			acl.SendError(w, err)
-			return
-		}
-		if tsv.sm.wantState == StateServing && !tsv.sm.IsServing() {
-			http.Error(w, "500 internal server error: vttablet is not serving", http.StatusInternalServerError)
-			return
-		}
-		w.Header().Set("Content-Length", fmt.Sprintf("%v", len(okMessage)))
-		w.WriteHeader(http.StatusOK)
-		w.Write(okMessage)
-	})
+	tsv.exporter.HandleFunc("/healthz", tsv.healthzHandler)
+}
+
+func (tsv *TabletServer) healthzHandler(w http.ResponseWriter, r *http.Request) {
+	if err := acl.CheckAccessHTTP(r, acl.MONITORING); err != nil {
+		acl.SendError(w, err)
+		return
+	}
+	if (tsv.sm.wantState == StateServing || tsv.sm.wantState == StateNotConnected) && !tsv.sm.IsServing() {
+		http.Error(w, "500 internal server error: vttablet is not serving", http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Length", fmt.Sprintf("%v", len(okMessage)))
+	w.WriteHeader(http.StatusOK)
+	w.Write(okMessage)
 }
 
 // Query service health check

go/vt/vttablet/tabletserver/tabletserver_test.go

@@ -22,6 +22,8 @@ import (
 	"io"
 	"io/ioutil"
 	"math/rand"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"reflect"
 	"strings"
@@ -56,6 +58,62 @@ import (
 	vtrpcpb "vitess.io/vitess/go/vt/proto/vtrpc"
 )
 
+func TestTabletServerHealthz(t *testing.T) {
+	db, tsv := setupTabletServerTest(t, "")
+	defer tsv.StopService()
+	defer db.Close()
+
+	req, err := http.NewRequest("GET", "/healthz", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(tsv.healthzHandler)
+	handler.ServeHTTP(rr, req)
+
+	expectedCode := http.StatusOK
+	if status := rr.Code; status != expectedCode {
+		t.Errorf("handler returned wrong status code: got %v want %v",
+			status, expectedCode)
+	}
+
+	expected := "ok\n"
+	if rr.Body.String() != expected {
+		t.Errorf("handler returned unexpected body: got %v want %v",
+			rr.Body.String(), expected)
+	}
+}
+
+func TestTabletServerHealthzNotConnected(t *testing.T) {
+	db, tsv := setupTabletServerTest(t, "")
+	defer tsv.StopService()
+	defer db.Close()
+
+	tsv.sm.SetServingType(topodatapb.TabletType_MASTER, time.Time{}, StateNotConnected, "test disconnected")
+
+	req, err := http.NewRequest("GET", "/healthz", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(tsv.healthzHandler)
+	handler.ServeHTTP(rr, req)
+
+	expectedCode := http.StatusInternalServerError
+	if status := rr.Code; status != expectedCode {
+		t.Errorf("handler returned wrong status code: got %v want %v",
+			status, expectedCode)
+	}
+
+	expected := "500 internal server error: vttablet is not serving\n"
+	if rr.Body.String() != expected {
+		t.Errorf("handler returned unexpected body: got %v want %v",
+			rr.Body.String(), expected)
+	}
+}
+
 func TestBeginOnReplica(t *testing.T) {
 	db, tsv := setupTabletServerTest(t, "")
 	defer tsv.StopService()