feat: Implement production mode license verification in VaadinServlet (#23864)

Add runtime license verification for production mode.
License check failure is only logged, it does not prevent the application from running.

Author: TatuLund

flow-data/src/test/java/com/vaadin/flow/data/provider/DataCommunicatorAsyncTest.java

@@ -25,10 +25,12 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
 
 import com.vaadin.flow.component.UI;
 import com.vaadin.flow.dom.Element;
+import com.vaadin.flow.function.DeploymentConfiguration;
 import com.vaadin.flow.internal.Range;
 import com.vaadin.flow.server.VaadinRequest;
 import com.vaadin.flow.server.VaadinService;
@@ -261,8 +263,9 @@ protected void init(VaadinRequest request) {
         private static VaadinSession findOrcreateSession() {
             VaadinSession session = VaadinSession.getCurrent();
             if (session == null) {
+                DeploymentConfiguration conf = Mockito.mock(DeploymentConfiguration.class);
                 session = new AlwaysLockedVaadinSession(
-                        new VaadinServletService(new VaadinServlet(), null));
+                        new VaadinServletService(new VaadinServlet(), conf));
                 VaadinSession.setCurrent(session);
             }
             return session;

flow-server/src/main/java/com/vaadin/flow/server/VaadinServlet.java

@@ -16,8 +16,6 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import com.vaadin.pro.licensechecker.BuildType;
-import com.vaadin.pro.licensechecker.LicenseChecker;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -40,6 +38,9 @@
 import com.vaadin.flow.server.HandlerHelper.RequestType;
 import com.vaadin.flow.server.startup.ApplicationConfiguration;
 import com.vaadin.flow.shared.JsonConstants;
+import com.vaadin.pro.licensechecker.BuildType;
+import com.vaadin.pro.licensechecker.LicenseChecker;
+import com.vaadin.pro.licensechecker.LicenseException;
 
 /**
  * The main servlet, which handles all incoming requests to the application.
@@ -59,6 +60,8 @@ public class VaadinServlet extends HttpServlet {
 
     public static final String INTERNAL_VAADIN_SERVLET_VITE_DEV_MODE_FRONTEND_PATH = "VAADIN_SERVLET_VITE_DEV_MODE_FRONTEND_PATH";
 
+    private static final String PROJECT_NAME = "flow";
+
     private VaadinServletService servletService;
     private StaticFileHandler staticFileHandler;
 
@@ -123,7 +126,8 @@ public void init(ServletConfig servletConfig) throws ServletException {
 
             try {
                 servletService = createServletService();
-                validateLicense(servletService.getDeploymentConfiguration());
+                verifyLicense(servletService.getDeploymentConfiguration()
+                        .isProductionMode());
             } catch (ServiceException e) {
                 throw new ServletException("Could not initialize VaadinServlet",
                         e);
@@ -142,6 +146,25 @@ public void init(ServletConfig servletConfig) throws ServletException {
         }
     }
 
+    private void verifyLicense(boolean productionMode) {
+        String frameworkVersion = Version.getFullVersion();
+        if (productionMode) {
+            try {
+                LicenseChecker.checkLicense(PROJECT_NAME, frameworkVersion,
+                        BuildType.PRODUCTION, null);
+            } catch (LicenseException e) {
+                getLogger().error(
+                        "This Vaadin version requires an extended maintenance subscription."
+                                + "Provide either a server key or an online license checking key,"
+                                + "which you can get from: https://vaadin.com/myaccount/licenses#latest.",
+                        e);
+            }
+        } else {
+            LicenseChecker.checkLicense(PROJECT_NAME, frameworkVersion,
+                    BuildType.DEVELOPMENT);
+        }
+    }
+
     private void detectFrontendMapping() {
         synchronized (VaadinServlet.class) {
             if (frontendMapping != null) {
@@ -622,13 +645,4 @@ private VaadinServletContext initializeContext() {
     public static String getFrontendMapping() {
         return frontendMapping;
     }
-
-    private void validateLicense(
-            DeploymentConfiguration deploymentConfiguration) {
-        // Check the license at runtime if in development mode
-        if (!deploymentConfiguration.isProductionMode()) {
-            LicenseChecker.checkLicense("flow", Version.getFullVersion(),
-                    BuildType.DEVELOPMENT);
-        }
-    }
 }

flow-server/src/test/java/com/vaadin/flow/server/VaadinServletTest.java

@@ -24,6 +24,7 @@
 import com.vaadin.flow.internal.VaadinContextInitializer;
 import com.vaadin.pro.licensechecker.BuildType;
 import com.vaadin.pro.licensechecker.LicenseChecker;
+import com.vaadin.pro.licensechecker.LicenseException;
 import net.jcip.annotations.NotThreadSafe;
 import org.junit.After;
 import org.junit.Assert;
@@ -384,11 +385,27 @@ public void checkLicense_devMode_licenseIsChecked()
     }
 
     @Test
-    public void checkLicense_prodMode_licenseIsNotChecked()
+    public void checkLicense_prodMode_licenseIsChecked()
             throws ServletException {
         Mockito.when(configuration.isProductionMode()).thenReturn(true);
         triggerLicenseChecking();
-        licenseChecker.verifyNoInteractions();
+        licenseChecker.verify(() -> LicenseChecker.checkLicense("flow",
+                Version.getFullVersion(), BuildType.PRODUCTION, null));
+    }
+
+    @Test
+    public void checkLicense_prodModeCheck_notFails()
+            throws ServletException {
+        licenseChecker
+                .when(() -> LicenseChecker.checkLicense("flow",
+                        Version.getFullVersion(), BuildType.PRODUCTION, null))
+                .thenThrow(new LicenseException("Test exception"));
+        try {
+            triggerLicenseChecking();
+        } catch (LicenseException e) {
+            Assert.fail(
+                    "License check should not throw exception in prod mode");
+        }
     }
 
     private ServletConfig mockConfig() {