[misc] Fix the realtime tests when running on CI (inside the xwiki/build...

[misc] Fix the realtime tests when running on CI (inside the xwiki/build Docker container with Jetty Standalone as servlet engine). In this case we shouldn't map the XWiki aliases to the Docker host but rather to the IP of the xwiki/build Docker container, but we need to determine it.

(cherry picked from commit 533156be)

xwiki-platform-core/xwiki-platform-test/xwiki-platform-test-docker/src/main/java/org/xwiki/test/docker/internal/junit5/browser/BrowserContainerExecutor.java

@@ -21,6 +21,11 @@
 
 import static org.xwiki.test.docker.internal.junit5.DockerTestUtils.startContainer;
 
+import java.io.IOException;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+
+import org.apache.commons.lang3.exception.ExceptionUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.testcontainers.containers.BrowserWebDriverContainer;
@@ -28,6 +33,7 @@
 import org.testcontainers.containers.output.Slf4jLogConsumer;
 import org.xwiki.test.docker.internal.junit5.AbstractContainerExecutor;
 import org.xwiki.test.docker.internal.junit5.BrowserTestUtils;
+import org.xwiki.test.docker.internal.junit5.DockerTestUtils;
 import org.xwiki.test.docker.junit5.TestConfiguration;
 import org.xwiki.test.docker.junit5.browser.Browser;
 
@@ -100,9 +106,13 @@ public BrowserWebDriverContainer start() throws Exception
         if (testConfiguration.getServletEngine().isOutsideDocker()) {
             // The servlet engine is running on the host so we need to map the servlet engine aliases to the host in
             // order for the browser to be able to access XWiki using the configured aliases.
-            testConfiguration.getServletEngineNetworkAliases().forEach(alias -> {
-                webDriverContainer.withExtraHost(alias, "host-gateway");
-            });
+            String host = DockerTestUtils.isInAContainer() ? getXWikiBuildContainerIPAddress() : "host-gateway";
+            if (this.testConfiguration.isVerbose()) {
+                LOGGER.info("Mapping servlet engine network aliases [{}] to [{}].",
+                    testConfiguration.getServletEngineNetworkAliases(), host);
+            }
+            testConfiguration.getServletEngineNetworkAliases()
+                .forEach(alias -> webDriverContainer.withExtraHost(alias, host));
         }
 
         // In case some test-resources are provided, they need to be available from the browser
@@ -125,6 +135,31 @@ public BrowserWebDriverContainer start() throws Exception
         return webDriverContainer;
     }
 
+    /**
+     * @return the IP address of the Docker container running the XWiki build
+     */
+    private String getXWikiBuildContainerIPAddress()
+    {
+        // This gives the local address that would be used to connect to the specified remote host. There is no real
+        // connection established, hence the specified remote IP can be unreachable.
+        try (DatagramSocket socket = new DatagramSocket()) {
+            socket.connect(InetAddress.getByName("8.8.8.8"), 10002);
+            String ipAddress = socket.getLocalAddress().getHostAddress();
+            if (this.testConfiguration.isVerbose()) {
+                LOGGER.info("The IP address of the XWiki build container is [{}].", ipAddress);
+            }
+            return ipAddress;
+        } catch (IOException e) {
+            // We assume the build container runs directly on the Docker host and uses the default bridge network.
+            String defaultIPAddress = "172.17.0.2";
+            LOGGER.warn(
+                "Failed to determine the IP address of the XWiki build container. Root cause: [{}]. "
+                    + "Falling back to the default IP address [{}].",
+                ExceptionUtils.getRootCauseMessage(e), defaultIPAddress);
+            return defaultIPAddress;
+        }
+    }
+
     /**
      * @return the path where the test resources are stored by Maven after test compilation, on the host.
      */