Third party Jar pom.xml

Question

We have a third party jar sitting in internal maven artifactory. We have to wrap it as docker image and persist in a docker registry. We have CI process in place to build a maven project and wrap it with docker and deploy it. But in this case, there is no additional java build process required as its a runnable 3rd party jar.

I know as part of CI step, we can do this and then continue to docker build

mvn dependency:copy -Dartifact=<org:artifact:version> -DoutputDirectory=<Path>/target

But this needs a custom CI step just to accommodate this. Question: Is there anyway that we can avoid this special CI step, probably by using a dummy wrapper pom.xml to download the thirdparty jar and make it as the build output.

Not married to maven, it can be gradle too.

Answer 1

The "copy" part seems to be trivial: you just need to add corresponding maven-dependency-plugin configuration to pom.xml and assign proper lifecycle phase to copy goal, for example, the configuration below:

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-dependency-plugin</artifactId>
 <executions>
  <execution>
   <id>copy</id>
   <goals>
    <goal>copy</goal>
   </goals>
   <phase>prepare-package</phase>
   <configuration>
    <artifactItems>
     <artifactItem>
      <groupId>tld.group</groupId>
      <artifactId>artifact</artifactId>
      <version>version</version>
      <outputDirectory>${project.build.directory}</outputDirectory>
      <destFileName>copy-of-artifact.jar</destFileName>
     </artifactItem>
    </artifactItems>
   </configuration>
  </execution>
 </executions>
</plugin>

causes maven to copy required jar into target directory during build lifecycle.

As regards to "mark third party jar as the build output" part, there are a couple of options:

I. basically, you may unpack third party jar into classes directory and ask maven-jar-plugin do not create manifest:

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-jar-plugin</artifactId>
 <configuration>
  <useDefaultManifestFile>true</useDefaultManifestFile>
 </configuration>
</plugin>

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-dependency-plugin</artifactId>
 <executions>
  <execution>
   <id>unpack</id>
   <goals>
    <goal>unpack</goal>
   </goals>
   <phase>prepare-package</phase>
   <configuration>
    <artifactItems>
     <artifactItem>
      <groupId>tld.group</groupId>
      <artifactId>artifact</artifactId>
      <version>version</version>
      <outputDirectory>${project.build.directory}/classes</outputDirectory>
     </artifactItem>
    </artifactItems>
   </configuration>
  </execution>
 </executions>
</plugin>

II. another option is to trick maven build via disabling maven-jar-plugin and modifying project's state using gmavenplus-plugin:

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-jar-plugin</artifactId>
 <executions>
  <execution>
   <id>default-jar</id>
   <phase>none</phase>
  </execution>
 </executions>
 <configuration>
  <skip>true</skip>
 </configuration>
</plugin>

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-dependency-plugin</artifactId>
 <executions>
  <execution>
   <id>copy</id>
   <goals>
    <goal>copy</goal>
   </goals>
   <phase>prepare-package</phase>
   <configuration>
    <artifactItems>
     <artifactItem>
      <groupId>tld.group</groupId>
      <artifactId>artifact</artifactId>
      <version>version</version>
      <outputDirectory>${project.build.directory}</outputDirectory>
      <destFileName>${project.build.finalName}.jar</destFileName>
     </artifactItem>
    </artifactItems>
   </configuration>
  </execution>
 </executions>
</plugin>

<plugin>
 <groupId>org.codehaus.gmavenplus</groupId>
 <artifactId>gmavenplus-plugin</artifactId>
 <version>1.13.1</version>
 <executions>
  <execution>
   <phase>package</phase>
   <goals>
    <goal>execute</goal>
   </goals>
   <configuration>
    <bindAllProjectProperties>true</bindAllProjectProperties>
    <scripts>
     <script><![CDATA[
project.artifact.file = new File("${project.build.directory}/${project.build.finalName}.jar")
  ]]></script>
    </scripts>
   </configuration>
  </execution>
 </executions>
 <dependencies>
  <dependency>
   <groupId>org.codehaus.groovy</groupId>
   <artifactId>groovy-all</artifactId>
   <version>3.0.9</version>
   <type>pom</type>
   <scope>runtime</scope>
  </dependency>
 </dependencies>
</plugin>