How can I define Plugin Versions correctly in maven pom.xml?

Question

I am struggeling in my attempts to create web-apps, and due to office conventions, I am using a Maven/Jetty/Eclipse setup, while attempting to create java web apps.

In my command window, I am trying to compile and run, by typing mvn jetty:run. This currently results in a lot of warnings, before I get a (very likely) related build failure. I would like to resolve these errors before moving on, even if they are not the reason of the build failure.

The warning message seems to say that I am missing declarations for versions of my plugins, and my attempts to search for help has suggested the same. I do however have versions defined. Another concern of mine is that the errors states that the warnings ie. come from line 13. This is an empty line. I am worried that there might be some update issues, or duplicated pom.xml-files, but on another note, the compiler does react to me editing in the file as I know it.

My error message is:

H:\projects\releaseplan>mvn jetty:run
[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for releaseplan:releaseplan-model:jar:5
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ releaseplan:releaseplan:5, H:\projects\releaseplan\pom.xml, line 13, column 15
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-source-plugin is missing. @ releaseplan:releaseplan:5, H:\projects\releaseplan\pom.xml, line 22, column 15
[WARNING]
[WARNING] Some problems were encountered while building the effective model for releaseplan:releaseplan-server:war:5
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ releaseplan:releaseplan:5, H:\projects\releaseplan\pom.xml, line 13, column 15
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-source-plugin is missing. @ releaseplan:releaseplan:5, H:\projects\releaseplan\pom.xml, line 22, column 15
[WARNING]
[WARNING] Some problems were encountered while building the effective model for releaseplan:releaseplan:pom:5
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ line 13, column 15
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-source-plugin is missing. @ line 22, column 15

And the entire pom.xml, in case the error is somewhere I do not expect it to be:

<?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/maven-v4_0_0.xsd">

<modelVersion>4.0.0</modelVersion>
<groupId>releaseplan</groupId>
<artifactId>releaseplan</artifactId>
<version>1</version>
<packaging>pom</packaging>
<name>releaseplan</name>

<build>

    <plugins>

        <!--<plugin> <groupId>ro.isdc.wro4j</groupId> <artifactId>wro4j-maven-plugin</artifactId> 
            <version>${wro4j.version}</version> <executions> <execution> <goals> <goal>jshint</goal> 
            </goals> </execution> </executions> <configuration> <options>devel,evil,noarg</options> 
            </configuration> </plugin> -->
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
            </configuration>
        </plugin>
        <plugin>
            <!-- Jetty Version: 8.x Home: Eclipse, Codehaus Java Version: 1.6 Protocols: 
                HTTP/1.1 RFC2616, WebSocket, SPDY Servlet Version: 3.0 JSP Version: 2.1 http://wiki.eclipse.org/Jetty -->
            <artifactId>jetty-maven-plugin</artifactId>
            <version>8.1.13.v20130916</version>
            <configuration>
                <webAppConfig>
                    <contextPath>/</contextPath>
                </webAppConfig>
                <scanIntervalSeconds>1</scanIntervalSeconds>
            </configuration>
        </plugin>
        <plugin>
            <artifactId>maven-antrun-plugin</artifactId>
            <executions>
                <execution>
                    <phase>initialize</phase>
                    <goals>
                        <goal>run</goal>
                    </goals>
                    <configuration>
                        <tasks>
                            <echo>********************************************</echo>
                            <echo>***** This project REQUIRES Maven 3.0+ *****</echo>
                            <echo>********************************************</echo>
                            <echo>mvn jetty:run - Running as un-assembled webapp</echo>
                            <echo>mvn jetty:run-war - Running as assembled webapp</echo>
                        </tasks>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>
<dependencyManagement>
    <dependencies>
        <!--  <dependency> <groupId>com.dyuproject.protostuff</groupId> <artifactId>protostuff-core</artifactId> 
            <version>${protostuff.version}</version> </dependency> <dependency> <groupId>com.dyuproject.protostuff</groupId> 
            <artifactId>protostuff-json</artifactId> <version>${protostuff.version}</version> 
            </dependency> -->
        <dependency>
            <groupId>org.mortbay.jetty</groupId>
            <artifactId>servlet-api</artifactId>
            <version>${servlet.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-core-asl</artifactId>
            <version>${jackson.version}</version>
        </dependency>
    </dependencies>
</dependencyManagement>

<modules>
    <module>model</module>
    <module>server</module>
</modules>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <compiler.source>1.5</compiler.source>
    <compiler.target>1.5</compiler.target>

    <junit.version>4.4</junit.version>
    <servlet.version>2.5-20081211</servlet.version>
    <jetty.version>6.1.24</jetty.version>
    <protobuf.version>2.3.0</protobuf.version>
    <jackson.version>1.7.9</jackson.version>
    <protostuff.version>1.0.2-SNAPSHOT</protostuff.version>
</properties>

 <repositories>
        <repository>
            <id>java</id>
            <name>java</name>
            <url>http://download.java.net/maven/2/</url>
        </repository>
        <repository>
            <id>repo1</id>
            <name>repo1</name>
            <url>http://repo1.maven.org/maven2</url>
        </repository>
    </repositories>



<pluginRepositories>
    <pluginRepository>
      <id>central</id>
      <name>Maven Plugin Repository</name>
      <url>http://repo1.maven.org/maven2</url>
      <layout>default</layout>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <releases>
        <updatePolicy>never</updatePolicy>
      </releases>
    </pluginRepository>
  </pluginRepositories>
</project>

Answer 1

You probably use Maven 3 which need to know all plugins versions as describe here : https://cwiki.apache.org/confluence/display/MAVEN/Maven+3.x+Compatibility+Notes#Maven3.xCompatibilityNotes-AutomaticPluginVersionResolution

Adding in the pluginManagement section of your parent pom.xml all plugins versions is the right way. The best way (in enterprise) is to have an enterprise parent pom.xml file used by all projects.

In fact, add the following line in your parent pom.xml properties section :

<maven-compiler-plugin.version>3.0</maven-compiler-plugin.version>

And add the following line in your parent pom.xml build > pluginManagement section :

<plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>${maven-compiler-plugin.version}</version>
</plugin>

Hope it helps...