vegardit-maven-parent - the Mother of all Maven parent POMs

1. What is it?
2. How to use
3. Changelog / Version History
4. License

What is it?

Opinionated best practices Maven parent project with the following 'features':

• Configures UTF-8 as default encoding of source files and generated reports.
• Configures the maven-toolchains-plugin to enable reproducible builds by decoupling the JDK used to run Maven and it's plugins from the JDK(s) used to compile and test code.
  Different JDKs - as defined in the local toolchains.xml - can be selected for the different build steps via Maven project properties like so:

  <properties>
     <!-- use Oracle JDK 11 for compilation -->
     <java.version>11</java.version>
     <java.vendor>oracle</java.vendor>
  
     <!-- use Open JDK 17 for running unit tests -->
     <java.version.unit-tests>17</java.version.unit-tests>
     <java.vendor.unit-tests>openjdk</java.vendor.unit-tests>
  
     <!-- use Open JDK 21 for running integration tests -->
     <java.version.integration-tests>21</java.version.integration-tests>
     <java.vendor.integration-tests>openjdk</java.vendor.integration-tests>
  </properties>

• Configures the Eclipse Java Compiler instead of javac:
  • to avoid the notorious schema change not supported error message when remote debugging via Eclipse.
  • to avoid javac bugs when targeting older JDKs, such as "JDK Bug 6302954: Type parameters of T cannot be determined; no unique maximal instance exists for type variable T with upper bounds U,X" which was only fixed 6 years after being reported.
    The Eclipse compiler is configured via a Groovy script in a toolchains-aware way - which is currently not possible when using plexus-compiler-eclipse or tycho-compiler-jdt.
• Allows you to use RELEASE as parent version value while maintaining reproducible builds of your released artifacts using this approach MRELEASE-399.
• Performs Maven project property resolution/replacement in resource files under src/main/resources whose names match:

  - META-INF/MANIFEST.MF
  - **/*.cfg
  - **/*.ini
  - **/*.html
  - **/*.md
  - **/*.props
  - **/*.properties
  - **/*.txt
  - **/*.xml
  - **/*.yaml
  - **/*.yml

• Configures the maven-enforcer-plugin to help maintaining Maven best practices.
• Configures the maven-checkstyle-plugin (including extra rules from the sevntu.checkstyle project) to be executed in the lifecycle phase process-sources.
  If the file src/etc/checkstyle.xml exists in the project being build, then this file will be the effective ruleset to checks against.
  If it does not exist then by default this checkstyle configuration file will be used.
  To use a different configuration file set one of the following project properties:
  • checkstyle.config.path: path to a config file on your local filesystem.
  • checkstyle.config.artifact: Maven artifact coordinates to a config file available in a configured Maven repository.
    The format is <groupId>:<artifactId>:<version>:<type>[:<classifier>], e.g. com.vegardit.maven:vegardit-maven-parent:2.1.3:xml:checkstyle.
• Configures the japicmp-maven-plugin to ensure SemVer-compliant binary compatibility between versions
• Configures the license-maven-plugin to block dependencies licensed under GPL/AGPL.
• Configures the jacoco-maven-plugin for test coverage.
• Executes test classes named *Test as unit-tests with the maven-surefire-plugin and test classes named *ITest as integration-tests with the maven-failsafe-plugin in the verify licefycle phase.
• Displays execution times of Maven plugins at the end of the build via maven-buildtime-extension, e.g.:

  [INFO] ------------------------------------------------------------------------
  [INFO] Total time:  6.175 s
  [INFO] Finished at: 2023-10-02T12:16:18+02:00
  [INFO] ------------------------------------------------------------------------
  [INFO] Build Time Summary:
  [INFO]
  [INFO] vegardit-maven-parent
  [INFO]   maven-enforcer-plugin:enforce (require-fixed-plugin-versio [0.010s]
  [INFO]   maven-enforcer-plugin:enforce (basic-checks@validate) .... [0.149s]
  [INFO]   japicmp-maven-plugin:cmp (cmp@package) ................... [0.194s]
  [INFO]   maven-checkstyle-plugin:check (check@process-sources) .... [0.848s]
  [INFO]   maven-site-plugin:attach-descriptor (attach-descriptor) .. [0.405s]
  [INFO]   maven-enforcer-plugin:enforce (enforce-bytecode-version@va [0.003s]
  [INFO]   jacoco-maven-plugin:report (post-unit-test) .............. [0.003s]
  [INFO]   maven-toolchains-plugin:toolchain (toolchain@validate) ... [0.031s]
  [INFO]   maven-bundle-plugin:manifest (manifest@process-classes) .. [0.008s]
  [INFO]   maven-dependency-plugin:properties (properties@initialize) [0.414s]
  [INFO]   exec-maven-plugin:exec (ecj@test-compile) ................ [0.001s]
  [INFO]   maven-clean-plugin:clean (default-clean) ................. [0.045s]
  [INFO]   gmavenplus-plugin:execute (groovy.script.onProcessResource [0.032s]
  [INFO]   build-helper-maven-plugin:attach-artifact (attach-files) . [0.003s]
  [INFO]   maven-enforcer-plugin:enforce (ban-duplicate-classes@valid [0.004s]
  [INFO]   exec-maven-plugin:exec (ecj@compile) ..................... [0.031s]
  [INFO]   jacoco-maven-plugin:prepare-agent (pre-unit-test) ........ [0.075s]
  [INFO]   maven-toolchains-plugin:toolchain (toolchain@process-test- [0.003s]
  [INFO]   dependencyversion-maven-plugin:set-version (set-version@in [0.063s]
  [INFO]   build-helper-maven-plugin:parse-version (parse-version) .. [0.036s]
  [INFO]   maven-antrun-plugin:run (delete-java-stubs@process-classes [0.022s]
  [INFO]   gmavenplus-plugin:execute (groovy.script.onInitialize@init [1.783s]
  [INFO]   license-maven-plugin:add-third-party (check-thirdparty-lic [0.467s]
  [INFO]   dependency-scope-maven-plugin:check (check@validate) ..... [0.128s]
  [INFO]   maven-enforcer-plugin:enforce (dependency-convergence@vali [0.006s]
  [INFO] ------------------------------------------------------------------------

• The jrebel-maven-plugin will be enabled automatically if the file src/main/resources/rebel-remote.xml is present in a project.

Additional Maven project properties

Additional Maven project properties are referenceable without any further configuration:

1. The os-maven-plugin is configured to provide platform-specific project properties that allows easy inclusion of native dependencies, e.g.

   <dependency>
      <groupId>io.netty</groupId>
      <artifactId>netty-tcnative</artifactId>
      <version>2.0.36</version>
      <classifier>${os.detected.classifier}</classifier> <!-- property "os.detected.classifier" is provided by os-maven-plugin -->
   </dependency>

2. The maven-dependency-plugin sets a property pointing to the artifact file for each project dependency following the pattern ${<groupId>:<artifactId>:<type>[:classifier]}, e.g. ${com.google.guava:guava:jar}.
   See "Stackoverflow: Can I use the path to a Maven dependency as a property?"
3. The dependencyversion-maven-plugin sets a property containing the version of each project dependency following the pattern ${<groupId>:<artifactId>:<type>[:classifier].version}, e.g. ${com.google.guava:guava:jar.version}.
4. The parse-version goal of the build-helper-maven-plugin sets the following properties:

   ${parsedVersion.majorVersion}
   ${parsedVersion.minorVersion}
   ${parsedVersion.incrementalVersion}
   ${parsedVersion.qualifier}
   ${parsedVersion.buildNumber}

Maven Site improvements:

1. WebDAV and SFTP protocols enabled for Maven site deployment.
2. Markdown rendering support is enabled by default via doxia-module-markdown
3. Contains workaround for SiteToolException: The site descriptor cannot be resolved from the repository: ArtifactResolutionException: Unable to locate site descriptor.
   See "Stackoverflow: How to avoid checking parent project in maven-site-plugin?" or "Unable to locate site descriptor : maven-site-plugin problem" for details.

Enables workarounds for some build annoyances such as:

1. Maven generate-sources goal being executed twice. See "Peter Lynch: How to prevent generate-sources phase executing twice" and "Stackoverflow: Maven phase executing twice"
2. Javadoc failing when incomplete tags exist on Java 8+. See "Stackoverflow: Maven is not working in Java 8 when Javadoc tags are incomplete"
3. getClass().getPackage().getImplementationVersion() for your classes in JARs and WARs will correctly return the Maven project version. See "Stackoverflow: Get Maven artifact version at runtime"

How to use

Using release builds

Releases of this project are available at https://search.maven.org/artifact/com.vegardit.maven/vegardit-maven-parent

Add the following parent declaration to your Maven project pom.xml.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <parent>
       <groupId>com.vegardit.maven</groupId>
       <artifactId>vegardit-maven-parent</artifactId>
       <version>RELEASE</version>
    </parent>

    <groupId><!-- your groupId here --></groupId>
    <artifactId><!-- your artifactId here --></artifactId>
    <version><!-- your version here --></version>

    <!-- ... other project settings --->
</project>

Using snapshot builds

Snapshots of this project are available at https://github.com/vegardit/vegardit-maven-parent/tree/mvn-snapshots-repo

Ensure your ~/.m2/settings.xml contains the project's snapshots repository, e.g.

<?xml version="1.0" encoding="UTF-8"?>
<settings xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.2.0 https://maven.apache.org/xsd/settings-1.2.0.xsd" xmlns="http://maven.apache.org/SETTINGS/1.2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <profiles>
      <profile>
         <id>vegardit-maven-parent-snapshots</id>
         <repositories>
            <repository>
                <id>vegardit-maven-parent-snapshots</id>
                <url>https://raw.githubusercontent.com/vegardit/vegardit-maven-parent/mvn-snapshots-repo/</url>
                <releases> <enabled>false</enabled></releases>
                <snapshots><enabled>true</enabled> </snapshots>
            </repository>
         </repositories>
      </profile>
   </profiles>
   <activeProfiles>
      <activeProfile>vegardit-maven-parent-snapshots</activeProfile>
   </activeProfiles>
</settings>

Add the following parent declaration to your Maven project pom.xml.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

   <modelVersion>4.0.0</modelVersion>

   <parent>
      <groupId>com.vegardit.maven</groupId>
      <artifactId>vegardit-maven-parent</artifactId>
      <version>LATEST</version>
   </parent>

   <groupId><!-- your groupId here --></groupId>
   <artifactId><!-- your artifactId here --></artifactId>
   <version><!-- your version here --></version>

   <!-- ... other project settings --->
</project>

Changelog / Version History

This project maintains a changelog and adheres to Semantic Versioning and Keep a CHANGELOG

License

All files are released under the Apache License 2.0.

Individual files contain the following tag instead of the full license text:

SPDX-License-Identifier: Apache-2.0

This enables machine processing of license information based on the SPDX License Identifiers that are available here: https://spdx.org/licenses/.