[MNG-7914] Provide a single entry point for configuration

apache-maven/src/assembly/maven/bin/m2.conf

@@ -1,6 +1,7 @@
 main is org.apache.maven.cli.MavenCli from plexus.core
 
 set maven.conf default ${maven.home}/conf
+set maven.installation.conf default ${maven.conf}
 
 [plexus.core]
 load       ${maven.conf}/logging

apache-maven/src/assembly/maven/conf/maven.properties

@@ -0,0 +1,40 @@
+#
+# Maven user properties
+#
+
+maven.installation.conf = ${maven.home}/conf
+maven.user.conf         = ${user.home}/.m2
+maven.project.conf      = ${session.rootDirectory}/.mvn
+
+# Comma-separated list of files to include.
+# Each item may be enclosed in quotes to gracefully include spaces. Items are trimmed before being loaded.
+# If the first character of an item is a question mark, the load will silently fail if the file does not exist.
+${includes} = ?"${maven.user.conf}/maven.properties", \
+              ?"${maven.project.conf}/maven.properties"
+
+#
+# Settings
+#
+# Define the default three levels for settings.
+# The '-is' flag will override the 'maven.installation.settings' property.
+# The '-ps' flag will override the 'maven.project.settings' property.
+# The '-s' flag will override the 'maven.user.settings' property.
+maven.installation.settings = ${maven.installation.conf}/settings.xml
+maven.project.settings      = ${maven.project.conf}/settings.xml
+maven.user.settings         = ${maven.user.conf}/settings.xml
+
+#
+# Toolchains
+#
+# Define the default three levels for toolchains.
+# The '-it' flag will override the 'maven.installation.toolchains' property.
+# The '-t' flag will override the 'maven.user.toolchains' property.
+maven.installation.toolchains = ${maven.installation.conf}/toolchains.xml
+maven.user.toolchains         = ${maven.user.conf}/toolchains.xml
+
+#
+# Extensions
+#
+maven.installation.extensions = ${maven.installation.conf}/extensions.xml
+maven.project.extensions      = ${maven.project.conf}/extensions.xml
+maven.user.extensions         = ${maven.user.conf}/extensions.xml

apache-maven/src/assembly/maven/conf/settings.xml

@@ -29,14 +29,15 @@ under the License.
  |
  |                 -s /path/to/user/settings.xml
  |
- |  2. Global Level. This settings.xml file provides configuration for all Maven
+ |  2. Installation Level.
+ |                 This settings.xml file provides configuration for all Maven
  |                 users on a machine (assuming they're all using the same Maven
  |                 installation). It's normally provided in
- |                 ${maven.conf}/settings.xml.
+ |                 ${maven.installation.conf}/settings.xml.
  |
  |                 NOTE: This location can be overridden with the CLI option:
  |
- |                 -gs /path/to/global/settings.xml
+ |                 -is /path/to/installation/settings.xml
  |
  | The sections in this sample file are intended to give you a running start at
  | getting the most out of your Maven installation. Where appropriate, the default

apache-maven/src/assembly/maven/conf/toolchains.xml

@@ -29,14 +29,15 @@ under the License.
  |
  |                 -t /path/to/user/toolchains.xml
  |
- |  2. Global Level. This toolchains.xml file provides configuration for all Maven
+ |  2. Installation Level.
+ |                 This toolchains.xml file provides configuration for all Maven
  |                 users on a machine (assuming they're all using the same Maven
  |                 installation). It's normally provided in
- |                 ${maven.conf}/toolchains.xml.
+ |                 ${maven.installation.conf}/toolchains.xml.
  |
  |                 NOTE: This location can be overridden with the CLI option:
  |
- |                 -gt /path/to/global/toolchains.xml
+ |                 -it /path/to/installation/toolchains.xml
  |
  | The sections in this sample file are intended to give you a running start at
  | getting the most out of your Maven installation.

apache-maven/src/test/java/org/apache/maven/settings/GlobalSettingsTest.java → apache-maven/src/test/java/org/apache/maven/settings/InstallationSettingsTest.java

@@ -29,10 +29,10 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
- * Tests that the global settings.xml shipped with the distribution is in good state.
+ * Tests that the installation settings.xml shipped with the distribution is in good state.
  *
  */
-class GlobalSettingsTest {
+class InstallationSettingsTest {
 
     @Test
     void testValidGlobalSettings() throws Exception {

api/maven-api-core/src/main/java/org/apache/maven/api/Constants.java

@@ -0,0 +1,267 @@
+/*
+ * 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.
+ */
+package org.apache.maven.api;
+
+import org.apache.maven.api.annotations.Config;
+
+/**
+ * Configuration constants.
+ */
+public final class Constants {
+
+    /**
+     * Maven home.
+     *
+     * @since 3.0.0
+     */
+    @Config(readOnly = true)
+    public static final String MAVEN_HOME = "maven.home";
+
+    /**
+     * Maven installation configuration directory.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.home}/conf")
+    public static final String MAVEN_INSTALLATION_CONF = "maven.installation.conf";
+
+    /**
+     * Maven user configuration directory.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${user.home}/.m2")
+    public static final String MAVEN_USER_CONF = "maven.user.conf";
+
+    /**
+     * Maven project configuration directory.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${session.rootDirectory}/.mvn")
+    public static final String MAVEN_PROJECT_CONF = "maven.project.conf";
+
+    /**
+     * Maven local repository.
+     *
+     * @since 3.0.0
+     */
+    @Config(defaultValue = "${maven.user.conf}/repository")
+    public static final String MAVEN_REPO_LOCAL = "maven.repo.local";
+
+    /**
+     * Maven installation settings.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.installation.conf}/settings.xml")
+    public static final String MAVEN_INSTALLATION_SETTINGS = "maven.installation.settings";
+
+    /**
+     * Maven user settings.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.user.conf}/settings.xml")
+    public static final String MAVEN_USER_SETTINGS = "maven.user.settings";
+
+    /**
+     * Maven project settings.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.project.conf}/settings.xml")
+    public static final String MAVEN_PROJECT_SETTINGS = "maven.project.settings";
+
+    /**
+     * Maven installation extensions.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.installation.conf}/extensions.xml")
+    public static final String MAVEN_INSTALLATION_EXTENSIONS = "maven.installation.extensions";
+
+    /**
+     * Maven user extensions.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.user.conf}/extensions.xml")
+    public static final String MAVEN_USER_EXTENSIONS = "maven.user.extensions";
+
+    /**
+     * Maven project extensions.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.project.conf}/extensions.xml")
+    public static final String MAVEN_PROJECT_EXTENSIONS = "maven.project.extensions";
+
+    /**
+     * Maven installation toolchains.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.installation.conf}/toolchains.xml")
+    public static final String MAVEN_INSTALLATION_TOOLCHAINS = "maven.installation.toolchains";
+
+    /**
+     * Maven user toolchains.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.user.home}/toolchains.xml")
+    public static final String MAVEN_USER_TOOLCHAINS = "maven.user.toolchains";
+
+    /**
+     * Extensions class path.
+     */
+    @Config
+    public static final String MAVEN_EXT_CLASS_PATH = "maven.ext.class.path";
+
+    /**
+     * Maven output color mode.
+     * Allowed values are <code>auto</code>, <code>always</code>, <code>never</code>.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "auto")
+    public static final String MAVEN_STYLE_COLOR_PROPERTY = "maven.style.color";
+
+    /**
+     * Build timestamp format.
+     *
+     * @since 3.0.0
+     */
+    @Config(source = Config.Source.MODEL, defaultValue = "yyyy-MM-dd'T'HH:mm:ssXXX")
+    public static final String MAVEN_BUILD_TIMESTAMP_FORMAT = "maven.build.timestamp.format";
+
+    /**
+     * User controlled relocations.
+     * This property is a comma separated list of entries with the syntax <code>GAV&gt;GAV</code>.
+     * The first <code>GAV</code> can contain <code>*</code> for any elem (so <code>*:*:*</code> would mean ALL, something
+     * you don't want). The second <code>GAV</code> is either fully specified, or also can contain <code>*</code>,
+     * then it behaves as "ordinary relocation": the coordinate is preserved from relocated artifact.
+     * Finally, if right hand <code>GAV</code> is absent (line looks like <code>GAV&gt;</code>), the left hand matching
+     * <code>GAV</code> is banned fully (from resolving).
+     * <br/>
+     * Note: the <code>&gt;</code> means project level, while <code>&gt;&gt;</code> means global (whole session level,
+     * so even plugins will get relocated artifacts) relocation.
+     * <br/>
+     * For example,
+     * <pre>maven.relocations.entries = org.foo:*:*>, \\<br/>    org.here:*:*>org.there:*:*, \\<br/>    javax.inject:javax.inject:1>>jakarta.inject:jakarta.inject:1.0.5</pre>
+     * means: 3 entries, ban <code>org.foo group</code> (exactly, so <code>org.foo.bar</code> is allowed),
+     * relocate <code>org.here</code> to <code>org.there</code> and finally globally relocate (see <code>&gt;&gt;</code> above)
+     * <code>javax.inject:javax.inject:1</code> to <code>jakarta.inject:jakarta.inject:1.0.5</code>.
+     *
+     * @since 4.0.0
+     */
+    @Config
+    public static final String MAVEN_RELOCATIONS_ENTRIES = "maven.relocations.entries";
+
+    /**
+     * User property for version filters expression, a semicolon separated list of filters to apply. By default, no version
+     * filter is applied (like in Maven 3).
+     * <br/>
+     * Supported filters:
+     * <ul>
+     *     <li>"h" or "h(num)" - highest version or top list of highest ones filter</li>
+     *     <li>"l" or "l(num)" - lowest version or bottom list of lowest ones filter</li>
+     *     <li>"s" - contextual snapshot filter</li>
+     *     <li>"e(G:A:V)" - predicate filter (leaves out G:A:V from range, if hit, V can be range)</li>
+     * </ul>
+     * Example filter expression: <code>"h(5);s;e(org.foo:bar:1)</code> will cause: ranges are filtered for "top 5" (instead
+     * full range), snapshots are banned if root project is not a snapshot, and if range for <code>org.foo:bar</code> is
+     * being processed, version 1 is omitted.
+     *
+     * @since 4.0.0
+     */
+    @Config
+    public static final String MAVEN_VERSION_FILTERS = "maven.versionFilters";
+
+    /**
+     * User property for chained LRM: list of "tail" local repository paths (separated by comma), to be used with
+     * {@code org.eclipse.aether.util.repository.ChainedLocalRepositoryManager}.
+     * Default value: <code>null</code>, no chained LRM is used.
+     *
+     * @since 3.9.0
+     */
+    @Config
+    public static final String MAVEN_REPO_LOCAL_TAIL = "maven.repo.local.tail";
+
+    /**
+     * User property for reverse dependency tree. If enabled, Maven will record ".tracking" directory into local
+     * repository with "reverse dependency tree", essentially explaining WHY given artifact is present in local
+     * repository.
+     * Default: <code>false</code>, will not record anything.
+     *
+     * @since 3.9.0
+     */
+    @Config(defaultValue = "false")
+    public static final String MAVEN_REPO_LOCAL_RECORD_REVERSE_TREE = "maven.repo.local.recordReverseTree";
+
+    /**
+     * User property for selecting dependency manager behaviour regarding transitive dependencies and dependency
+     * management entries in their POMs. Maven 3 targeted full backward compatibility with Maven2, hence it ignored
+     * dependency management entries in transitive dependency POMs. Maven 4 enables "transitivity" by default, hence
+     * unlike Maven2, obeys dependency management entries deep in dependency graph as well.
+     * <br/>
+     * Default: <code>"true"</code>.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "true")
+    public static final String MAVEN_RESOLVER_DEPENDENCY_MANAGER_TRANSITIVITY =
+            "maven.resolver.dependencyManagerTransitivity";
+
+    /**
+     * Resolver transport to use.
+     * Can be <code>default</code>, <code>wagon</code>, <code>apache</code>, <code>jdk</code> or <code>auto</code>.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "default")
+    public static final String MAVEN_RESOLVER_TRANSPORT = "maven.resolver.transport";
+
+    /**
+     * Plugin validation level.
+     *
+     * @since 3.9.2
+     */
+    @Config(defaultValue = "inline")
+    public static final String MAVEN_PLUGIN_VALIDATION = "maven.plugin.validation";
+
+    /**
+     * Plugin validation exclusions.
+     *
+     * @since 3.9.6
+     */
+    @Config
+    public static final String MAVEN_PLUGIN_VALIDATION_EXCLUDES = "maven.plugin.validation.excludes";
+
+    /**
+     * ProjectBuilder parallelism.
+     *
+     * @since 4.0.0
+     */
+    @Config(type = "java.lang.Integer", defaultValue = "cores/2 + 1")
+    public static final String MAVEN_PROJECT_BUILDER_PARALLELISM = "maven.projectBuilder.parallelism";
+
+    private Constants() {}
+}