GH-15742: added db health check method in app (#15752)

app/app.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/mattermost/go-i18n/i18n"
 	goi18n "github.com/mattermost/go-i18n/i18n"
@@ -677,3 +678,21 @@ func (a *App) SetServer(srv *Server) {
 func (a *App) GetT() goi18n.TranslateFunc {
 	return a.t
 }
+
+func (a *App) DBHealthCheckWrite() error {
+	currentTime := strconv.FormatInt(time.Now().Unix(), 10)
+
+	return a.Srv().Store.System().SaveOrUpdate(&model.System{
+		Name:  a.dbHealthCheckKey(),
+		Value: currentTime,
+	})
+}
+
+func (a *App) DBHealthCheckDelete() error {
+	_, err := a.Srv().Store.System().PermanentDeleteByName(a.dbHealthCheckKey())
+	return err
+}
+
+func (a *App) dbHealthCheckKey() string {
+	return fmt.Sprintf("health_check_%s", a.GetClusterId())
+}