chore(spring-boot-webapp): introduce filter to make URLs without trailing slashes work

spring-boot-starter/starter-webapp-core/src/main/java/org/camunda/bpm/spring/boot/starter/webapp/CamundaBpmWebappInitializer.java

@@ -19,17 +19,15 @@
 import static java.util.Collections.singletonMap;
 import static org.glassfish.jersey.servlet.ServletProperties.JAXRS_APPLICATION_CLASS;
 
-import java.util.Collections;
-import java.util.EnumSet;
-import java.util.Map;
-
 import jakarta.servlet.DispatcherType;
 import jakarta.servlet.Filter;
 import jakarta.servlet.FilterRegistration;
 import jakarta.servlet.ServletContext;
 import jakarta.servlet.ServletRegistration;
 import jakarta.servlet.SessionTrackingMode;
-
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.Map;
 import org.camunda.bpm.admin.impl.web.AdminApplication;
 import org.camunda.bpm.admin.impl.web.bootstrap.AdminContainerBootstrap;
 import org.camunda.bpm.cockpit.impl.web.CockpitApplication;
@@ -38,6 +36,7 @@
 import org.camunda.bpm.engine.rest.filter.EmptyBodyFilter;
 import org.camunda.bpm.spring.boot.starter.property.CamundaBpmProperties;
 import org.camunda.bpm.spring.boot.starter.property.WebappProperty;
+import org.camunda.bpm.spring.boot.starter.webapp.filter.AppendTrailingSlashFilter;
 import org.camunda.bpm.spring.boot.starter.webapp.filter.LazyProcessEnginesFilter;
 import org.camunda.bpm.spring.boot.starter.webapp.filter.LazySecurityFilter;
 import org.camunda.bpm.tasklist.impl.web.TasklistApplication;
@@ -92,6 +91,14 @@ public void onStartup(ServletContext servletContext) {
 
     ServletContextUtil.setAppPath(applicationPath, servletContext);
 
+    // make sure that trailing slashes are added for the registered patterns
+    // see AppendTrailingSlashFilter for details
+    registerFilter("AppendTrailingSlashFilter", AppendTrailingSlashFilter.class,
+        applicationPath + "/app",
+        applicationPath + "/app/cockpit",
+        applicationPath + "/app/admin",
+        applicationPath + "/app/tasklist",
+        applicationPath + "/app/welcome");
     registerFilter("Authentication Filter", AuthenticationFilter.class,
         Collections.singletonMap("cacheTimeToLive", getAuthCacheTTL(webapp)),
         applicationPath + "/api/*", applicationPath + "/app/*");

spring-boot-starter/starter-webapp-core/src/main/java/org/camunda/bpm/spring/boot/starter/webapp/filter/AppendTrailingSlashFilter.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
+ * under one or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership. Camunda licenses this file to you under the Apache License,
+ * Version 2.0; you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.camunda.bpm.spring.boot.starter.webapp.filter;
+
+import jakarta.servlet.Filter;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+/**
+ * Servlet filter to ensure request paths always have a trailing slash. Before Spring Boot 3, missing trailing slashes were
+ * handled automatically. This filter implements the Spring Boot 2 behavior for the registered request patterns.
+ *
+ * @see https://github.com/spring-projects/spring-framework/issues/28552
+ */
+public class AppendTrailingSlashFilter implements Filter {
+
+  @Override
+  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+      throws IOException, ServletException {
+    String requestURI = ((HttpServletRequest) request).getRequestURI();
+    ((HttpServletResponse) response).sendRedirect(requestURI + "/");
+  }
+
+}

spring-boot-starter/starter-webapp-core/src/test/java/org/camunda/bpm/spring/boot/starter/webapp/apppath/RequestTrailingSlashIT.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
+ * under one or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership. Camunda licenses this file to you under the Apache License,
+ * Version 2.0; you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.camunda.bpm.spring.boot.starter.webapp.apppath;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import org.camunda.bpm.spring.boot.starter.webapp.TestApplication;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.test.web.server.LocalServerPort;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(
+    classes = { TestApplication.class },
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class RequestTrailingSlashIT {
+
+  public static final List<String> REDIRECT_PATHS = List.of("/app", "/app/cockpit", "/app/admin", "/app/tasklist", "/app/welcome");
+
+  TestRestTemplate client = new TestRestTemplate();
+
+  @LocalServerPort
+  public int port;
+
+  @Test
+  public void shouldRedirectPathWithMissingTrailingSlash() throws IOException {
+    // given
+    List<ResponseEntity<String>> responses = new ArrayList<>();
+
+    // when calling different paths with and without trailing slashes
+    for (String path : REDIRECT_PATHS) {
+      String url = "http://localhost:" + port + "/camunda" + path;
+      responses.add(client.getForEntity(url, String.class));
+      responses.add(client.getForEntity(url + "/", String.class));
+    }
+
+    // then all paths should be found
+    assertThat(responses).extracting("statusCode").containsOnly(HttpStatus.OK);
+  }
+
+}