java - Packaging a jar into a dist dir with separated external resources and dependencies

Question

Here's what I'm trying to achieve - a dist directory (or a zip file) that looks like this:

dist/
|-- application-1.0.jar
|-- conf/
    |-- application.properties
    |-- log4j.properties
|-- lib/
    |-- *.jar

Basically:

• An executable jar is produced (with appropriate classpath in the manifest)
• I want to exclude src/main/resources from being automatically packaged with the jar, so that application.properties can be modified
• I want to have external dependencies in the lib/ directory

I came up with a solution using a profile with plugins attached to the package phase, but would using the assembly plugin be a better solution?

Answer 1

The solution using the assembly plugin has a few parts:

• The pom includes configuring the jar plugin (maven-jar-plugin), and configuring the assembly plugin (maven-assembly-plugin).
• During maven's packaging phase, the jar plugin is called to construct the application jar.
• Then the assembly plugin is run, and combines the constructed jar, resources and dependencies into a zip file as defined by the assembly file (distribution-zip.xml).

In the pom, configure the plugins:

<build>
    <plugins>
        <plugin>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.2</version>
            <configuration>
                <archive>
                    <!-- Make an executable jar, adjust classpath entries-->
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <classpathPrefix>./lib/</classpathPrefix>
                        <mainClass>com.acme.KillerApp</mainClass>
                    </manifest>
                    <!--Resources will be placed under conf/-->
                    <manifestEntries>
                        <Class-Path>./conf/</Class-Path>
                    </manifestEntries>
                </archive>
                <!--exclude the properties file from the archive-->
                <excludes>
                    <exclude>*.properties</exclude>
                </excludes>
            </configuration>
        </plugin>

        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.2-beta-5</version>
            <configuration>
                <descriptors>
                    <descriptor>${basedir}/assembly/distribution-zip.xml</descriptor>
                </descriptors>
            </configuration>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
...

The contents of the assembly file distribution-zip.xml (with thanks to Neeme Praks) combines the created jar, resources and dependencies:

<assembly>
    <id>dist</id>
    <formats>
        <format>zip</format>
    </formats>

    <includeBaseDirectory>true</includeBaseDirectory>

    <dependencySets>
        <dependencySet>
            <!--Include runtime dependencies-->
            <outputDirectory>lib</outputDirectory>
            <scope>runtime</scope>
        </dependencySet>
    </dependencySets>

    <fileSets>
        <fileSet>
            <!--Get the generated application jar-->
            <directory>${project.build.directory}</directory>
            <outputDirectory>/</outputDirectory>
            <includes>
                <include>*.jar</include>
            </includes>
        </fileSet>
        <fileSet>
            <!--Get application resources-->
            <directory>src/main/resources</directory>
            <outputDirectory>conf</outputDirectory>
        </fileSet>
        <fileSet>
            <!--Get misc user files-->
            <directory>${project.basedir}</directory>
            <outputDirectory>/</outputDirectory>
            <includes>
                <include>README*</include>
                <include>LICENSE*</include>
                <include>NOTICE*</include>
            </includes>
        </fileSet>       
    </fileSets>
</assembly>

The resulting distributable zip file is created like target/killer-app-1.0-dist.zip!