[ACS-12601] Allow discovery API in read-only mode (#4352)

remote-api/src/main/resources/alfresco/templates/publicapi/org/alfresco/api/DiscoveryApiWebscript.get.desc.xml

@@ -4,7 +4,7 @@
     <description>Returns repository information</description>
     <url>/discovery</url>
     <authentication>user</authentication>
-    <transaction>required</transaction>
+    <transaction allow="readonly">required</transaction>
     <format default="json">argument</format>
     <lifecycle>public_api</lifecycle>
 </webscript>

remote-api/src/test/java/org/alfresco/AppContext02TestSuite.java

@@ -2,7 +2,7 @@
  * #%L
  * Alfresco Repository
  * %%
- * Copyright (C) 2005 - 2021 Alfresco Software Limited
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
  * %%
  * This file is part of the Alfresco software.
  * If the software was purchased under a paid Alfresco license, the terms of
@@ -49,6 +49,7 @@ import org.alfresco.util.testing.category.NonBuildTests;
         org.alfresco.rest.api.tests.ActivitiesPostingTest.class,
         org.alfresco.rest.api.tests.AuthenticationsTest.class,
         org.alfresco.rest.api.tests.DiscoveryApiTest.class,
+        org.alfresco.rest.api.tests.DiscoveryInReadOnlyModeTest.class,
         org.alfresco.rest.api.discovery.DiscoveryApiWebscriptUnitTest.class,
         org.alfresco.rest.api.tests.GroupsTest.class,
         org.alfresco.rest.api.tests.ModulePackagesApiTest.class,

remote-api/src/test/java/org/alfresco/rest/api/tests/DiscoveryInReadOnlyModeTest.java

@@ -0,0 +1,87 @@
+/*
+ * #%L
+ * Alfresco Repository
+ * %%
+ * Copyright (C) 2025 - 2026 Alfresco Software Limited
+ * %%
+ * This file is part of the Alfresco software.
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ * #L%
+ */
+
+package org.alfresco.rest.api.tests;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import org.alfresco.repo.transaction.TransactionServiceImpl;
+import org.alfresco.rest.AbstractSingleNetworkSiteTest;
+import org.alfresco.rest.api.tests.client.HttpResponse;
+import org.alfresco.rest.api.tests.client.data.Node;
+import org.alfresco.rest.api.tests.util.RestApiUtil;
+import org.alfresco.service.ServiceRegistry;
+
+public class DiscoveryInReadOnlyModeTest extends AbstractSingleNetworkSiteTest
+{
+    @Test
+    public void testReadOnlyServerCanCallDiscovery() throws Exception
+    {
+        TransactionServiceImpl transactionService = (TransactionServiceImpl) applicationContext.getBean(ServiceRegistry.TRANSACTION_SERVICE.getLocalName());
+        try
+        {
+            transactionService.setAllowWrite(false);
+            setRequestContext(user1);
+            verifySystemIsInReadOnlyMode();
+
+            // discovery must remain accessible even when the repository is in read-only mode
+            get("discovery", null, 200);
+        }
+        finally
+        {
+            transactionService.setAllowWrite(true);
+        }
+    }
+
+    private void verifySystemIsInReadOnlyMode() throws IOException
+    {
+        Node n = new Node();
+        n.setName("test-folder-any-name-" + RUNID);
+        n.setNodeType(TYPE_CM_FOLDER);
+
+        HttpResponse response = publicApiClient.post(getScope(), getNodeChildrenUrl(getNodeId()), null, null, null, RestApiUtil.toJsonAsStringNonNull(n));
+        assertThat(response.getStatusCode()).isEqualTo(403);
+        assertThat(response.getResponse()).contains("The system is currently in read-only mode.");
+    }
+
+    private String getNodeId()
+    {
+        try
+        {
+            return getMyNodeId();
+        }
+        catch (Exception e)
+        {
+            fail("Test setup failure: unable to get My Node ID", e);
+            return null;
+        }
+    }
+}