[MNG-5913] Allow defining aliases for existing server configurations in settings.xml

api/maven-api-settings/pom.xml

@@ -54,6 +54,9 @@ under the License.
         <groupId>org.codehaus.modello</groupId>
         <artifactId>modello-maven-plugin</artifactId>
         <configuration>
+          <pluralExceptions>
+            <aliases>alias</aliases>
+          </pluralExceptions>
           <version>2.0.0</version>
           <velocityBasedir>${project.basedir}/../../src/mdo</velocityBasedir>
           <models>

api/maven-api-settings/src/main/mdo/settings.mdo

@@ -529,6 +529,18 @@
             Extra configuration for the transport layer.
           </description>
         </field>
+        <field>
+          <name>aliases</name>
+          <version>1.3.0+</version>
+          <description>List of additional server aliases. For each alias, an additional server entry will be generated
+            with the same configuration as the original one, but with the ID replaced by the alias
+            and with an empty aliases list.
+            This is useful when the same credentials should be used for multiple servers.</description>
+          <association>
+            <type>String</type>
+            <multiplicity>*</multiplicity>
+          </association>
+        </field>
       </fields>
     </class>
     <class>

compat/maven-settings-builder/src/main/java/org/apache/maven/settings/building/DefaultSettingsBuilder.java

@@ -26,12 +26,15 @@
 import java.io.IOException;
 import java.io.StringReader;
 import java.io.StringWriter;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Stream;
 
 import org.apache.maven.building.FileSource;
 import org.apache.maven.building.Source;
+import org.apache.maven.settings.Server;
 import org.apache.maven.settings.Settings;
 import org.apache.maven.settings.TrackableBase;
 import org.apache.maven.settings.io.SettingsParseException;
@@ -182,6 +185,7 @@ private Settings readSettings(
         }
 
         settingsValidator.validate(settings, problems);
+        settings.setServers(new ArrayList<>(serversByIds(settings.getServers())));
 
         return settings;
     }
@@ -251,4 +255,18 @@ public Object execute(String expression, Object value) {
 
         return result;
     }
+
+    private List<Server> serversByIds(List<Server> servers) {
+        return servers.stream()
+                .flatMap(server -> Stream.concat(
+                        Stream.of(server), server.getAliases().stream().map(id -> serverAlias(server, id))))
+                .toList();
+    }
+
+    private Server serverAlias(Server server, String id) {
+        return new Server(org.apache.maven.api.settings.Server.newBuilder(server.getDelegate(), true)
+                .id(id)
+                .aliases(List.of())
+                .build());
+    }
 }

compat/maven-settings-builder/src/main/java/org/apache/maven/settings/validation/DefaultSettingsValidator.java

@@ -93,6 +93,23 @@ public void validate(Settings settings, SettingsProblemCollector problems) {
                             "must be unique but found duplicate server with id " + server.getId());
                 }
             }
+
+            for (int i = 0; i < servers.size(); i++) {
+                Server server = servers.get(i);
+                for (int a = 0; a < server.getAliases().size(); a++) {
+                    String alias = server.getAliases().get(a);
+                    validateStringNotEmpty(
+                            problems, "servers.server[" + i + "].aliases[" + a + "]", alias, server.getId());
+                    if (!serverIds.add(alias)) {
+                        addViolation(
+                                problems,
+                                Severity.WARNING,
+                                "servers.server[" + i + "].aliases[" + a + "]",
+                                server.getId(),
+                                "must be unique across all server ids and aliases but found duplicate alias " + alias);
+                    }
+                }
+            }
         }
 
         List<Mirror> mirrors = settings.getMirrors();

compat/maven-settings-builder/src/test/java/org/apache/maven/settings/building/DefaultSettingsBuilderFactoryTest.java

@@ -19,10 +19,16 @@
 package org.apache.maven.settings.building;
 
 import java.io.File;
+import java.util.List;
+import java.util.Properties;
 
+import org.apache.maven.api.settings.Server;
+import org.apache.maven.settings.Settings;
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  */
@@ -32,17 +38,101 @@ private File getSettings(String name) {
         return new File("src/test/resources/settings/factory/" + name + ".xml").getAbsoluteFile();
     }
 
-    @Test
-    void testCompleteWiring() throws Exception {
+    SettingsBuildingResult execute(String settingsName) throws Exception {
+        Properties properties = new Properties();
+        properties.setProperty("user.home", "/home/user");
+
         SettingsBuilder builder = new DefaultSettingsBuilderFactory().newInstance();
         assertNotNull(builder);
 
         DefaultSettingsBuildingRequest request = new DefaultSettingsBuildingRequest();
-        request.setSystemProperties(System.getProperties());
-        request.setUserSettingsFile(getSettings("simple"));
+        request.setSystemProperties(properties);
+        request.setUserSettingsFile(getSettings(settingsName));
 
         SettingsBuildingResult result = builder.build(request);
         assertNotNull(result);
-        assertNotNull(result.getEffectiveSettings());
+        return result;
+    }
+
+    @Test
+    void testCompleteWiring() throws Exception {
+        Settings settings = execute("simple").getEffectiveSettings();
+
+        String localRepository = settings.getLocalRepository();
+        assertTrue(localRepository.equals("/home/user/.m2/repository")
+                || localRepository.endsWith("\\home\\user\\.m2\\repository"));
+    }
+
+    @Test
+    void testSettingsWithServers() throws Exception {
+        Settings settings = execute("settings-servers-1").getEffectiveSettings();
+
+        List<Server> servers = settings.getDelegate().getServers();
+        assertEquals(2, servers.size());
+
+        Server server1 = getServerById(servers, "server-1");
+        assertEquals("username1", server1.getUsername());
+        assertEquals("password1", server1.getPassword());
+
+        Server server2 = getServerById(servers, "server-2");
+        assertEquals("username2", server2.getUsername());
+        assertEquals("password2", server2.getPassword());
+    }
+
+    @Test
+    void testSettingsWithServersAndAliases() throws Exception {
+        Settings settings = execute("settings-servers-2").getEffectiveSettings();
+
+        List<Server> servers = settings.getDelegate().getServers();
+        assertEquals(6, servers.size());
+
+        Server server1 = getServerById(servers, "server-1");
+        assertEquals("username1", server1.getUsername());
+        assertEquals("password1", server1.getPassword());
+        assertEquals(List.of("server-11", "server-12"), server1.getAliases());
+
+        Server server11 = getServerById(servers, "server-11");
+        assertEquals("username1", server11.getUsername());
+        assertEquals("password1", server11.getPassword());
+        assertTrue(server11.getAliases().isEmpty());
+
+        Server server12 = getServerById(servers, "server-12");
+        assertEquals("username1", server12.getUsername());
+        assertEquals("password1", server12.getPassword());
+        assertTrue(server12.getAliases().isEmpty());
+
+        Server server2 = getServerById(servers, "server-2");
+        assertEquals("username2", server2.getUsername());
+        assertEquals("password2", server2.getPassword());
+        assertEquals(List.of("server-21"), server2.getAliases());
+
+        Server server21 = getServerById(servers, "server-21");
+        assertEquals("username2", server21.getUsername());
+        assertEquals("password2", server21.getPassword());
+        assertTrue(server21.getAliases().isEmpty());
+
+        Server server3 = getServerById(servers, "server-3");
+        assertEquals("username3", server3.getUsername());
+        assertEquals("password3", server3.getPassword());
+        assertTrue(server3.getAliases().isEmpty());
+    }
+
+    private Server getServerById(List<Server> servers, String id) {
+        return servers.stream()
+                .filter(s -> s.getId().equals(id))
+                .findFirst()
+                .orElseThrow(
+                        () -> new IllegalStateException("Server with id " + id + " not found on list: " + servers));
+    }
+
+    @Test
+    void testSettingsWithDuplicateServersIds() throws Exception {
+        SettingsBuildingResult result = execute("settings-servers-3");
+
+        List<SettingsProblem> problems = result.getProblems();
+        assertEquals(1, problems.size());
+        assertEquals(
+                "'servers.server[0].aliases[0]' for server-1 must be unique across all server ids and aliases but found duplicate alias server-2",
+                problems.get(0).getMessage());
     }
 }

compat/maven-settings-builder/src/test/java/org/apache/maven/settings/validation/DefaultSettingsValidatorTest.java

@@ -219,6 +219,58 @@ void testValidateProxy() throws Exception {
         assertContains(problems.messages.get(0), "'proxies.proxy.host' for default is missing");
     }
 
+    @Test
+    void testValidateServerIdAlias() {
+        Settings settings = new Settings();
+        Server server = new Server();
+        server.setId("server-1");
+        server.addAlias("server-1");
+        settings.addServer(server);
+
+        SimpleProblemCollector problems = new SimpleProblemCollector();
+        validator.validate(settings, problems);
+        assertEquals(1, problems.messages.size());
+        assertContains(
+                problems.messages.get(0),
+                "'servers.server[0].aliases[0]' for server-1 must be unique across all server ids and aliases but found duplicate alias server-1");
+    }
+
+    @Test
+    void testMultipleUsageOfAliases() {
+        Settings settings = new Settings();
+
+        Server server1 = new Server();
+        server1.setId("server-1");
+        server1.addAlias("alias-1");
+        settings.addServer(server1);
+
+        Server server2 = new Server();
+        server2.setId("server-2");
+        server2.addAlias("alias-1");
+        settings.addServer(server2);
+
+        SimpleProblemCollector problems = new SimpleProblemCollector();
+        validator.validate(settings, problems);
+        assertEquals(1, problems.messages.size());
+        assertContains(
+                problems.messages.get(0),
+                "'servers.server[1].aliases[0]' for server-2 must be unique across all server ids and aliases but found duplicate alias alias-1");
+    }
+
+    @Test
+    void testValidateServerIdAliasesWithEmptyValue() {
+        Settings settings = new Settings();
+        Server server = new Server();
+        server.setId("server-1");
+        server.addAlias("");
+        settings.addServer(server);
+
+        SimpleProblemCollector problems = new SimpleProblemCollector();
+        validator.validate(settings, problems);
+        assertEquals(1, problems.messages.size());
+        assertContains(problems.messages.get(0), "'servers.server[0].aliases[0]' for server-1 is missing");
+    }
+
     private static class SimpleProblemCollector implements SettingsProblemCollector {
 
         List<String> messages = new ArrayList<>();

compat/maven-settings-builder/src/test/resources/settings/factory/settings-servers-1.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); 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.
+-->
+
+<settings>
+  <localRepository>${user.home}/.m2/repository</localRepository>
+  <servers>
+    <server>
+      <id>server-1</id>
+      <username>username1</username>
+      <password>password1</password>
+    </server>
+    <server>
+      <id>server-2</id>
+      <username>username2</username>
+      <password>password2</password>
+    </server>
+  </servers>
+
+</settings>

compat/maven-settings-builder/src/test/resources/settings/factory/settings-servers-2.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); 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.
+-->
+
+<settings>
+  <localRepository>${user.home}/.m2/repository</localRepository>
+  <servers>
+    <server>
+      <id>server-1</id>
+      <aliases>
+        <alias>server-11</alias>
+        <alias>server-12</alias>
+      </aliases>
+      <username>username1</username>
+      <password>password1</password>
+    </server>
+    <server>
+      <id>server-2</id>
+      <aliases>
+        <alias>server-21</alias>
+      </aliases>
+      <username>username2</username>
+      <password>password2</password>
+    </server>
+    <server>
+      <id>server-3</id>
+      <username>username3</username>
+      <password>password3</password>
+    </server>
+  </servers>
+
+</settings>