10

We have large project that uses Maven as a build system. We decided that in future projects we will use Gradle as more convenient tool, but we want to use Gradle for our legacy project too.

I think that migrating from Maven to Gradle at one time will be very painful, because we have TONS of code in POM files (we have really heavy build logic).

I know, that Gradle have automigration tool (gradle init) but it doesn't work properly (I think this tool is for small Maven projects with no specific build logic).

So, here is a question: can I include Gradle module to Maven project to migrate with small steps? Maybe there is Maven plugin, that allows to treat build.gradle as pom.xml file?

Anton Dzodzikov
  • 129
  • 1
  • 6

3 Answers3

8

There is a gradle-maven-plugin which allows you to run Gradle tasks from within Maven. From the plugin description:

To use the plugin, simply declare the plugin and bind it to the maven lifecycle phase of your choice:

<plugin>
    <groupId>org.fortasoft</groupId>
    <artifactId>gradle-maven-plugin</artifactId>
    <version>1.0.8</version>
    <configuration>
        <tasks>
            <!-- this would effectively call "gradle doSomething" -->
            <task>doSomething</task>
        </tasks>
    </configuration>
    <executions>
        <execution>
            <!-- You can bind this to any phase you like -->
            <phase>compile</phase>
            <goals>
                <!-- goal must be "invoke" -->
                <goal>invoke</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Now when you run maven, gradle will be invoked and execute the "doSomething" task defined in build.gradle.

Obviously you can change the task(s) to suit your needs.

In this example, the gradle invocation will happen during the maven "compile" phase, but this can be easily changed by changing the element value.

Not sure, how to include artifacts of Gradle build to your dependencies, may be you'll need to post this artifact to local maven repository, to make it available for your maven project.

Stanislav
  • 27,441
  • 9
  • 87
  • 82
  • Please note: this project is not updated from 2016, Gradle 2.13 is used. – crimaniak Feb 12 '20 at 16:02
  • @crimaniak Use the maintained fork at: https://github.com/raphw/gradle-maven-plugin – Jay Taylor Mar 26 '20 at 22:55
  • @Jay Taylor Thank for the link. It's a pity, I found this approach doesn't work for me. I have a huge project with thousands of modules with a maven build time of about 15 minutes for one configuration. There a lot of custom things used, profiles, variables, etc., so it's hard to convert it to Gradle. Idea was to convert it by module basis and use this plugin to build converted modules by Gradle. But I found maven still try to find an answer to The Ultimate Question of Life, the Universe, and Everything before running Gradle, so this approach don't give me benefit. – crimaniak Apr 01 '20 at 23:14
4

You might find my gradle-maven-share plugin useful. It's designed to help migrating from maven to gradle by sharing the maven config with gradle.

lance-java
  • 25,497
  • 4
  • 59
  • 101
0

I probably would use:

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>exec-maven-plugin</artifactId>
  <executions>
    <execution>
      <id>test</id>
      <phase>test</phase>
      <configuration>
        <executable>./gradlew</executable>
        <arguments>
          <argument>test</argument>
          <argument>-i</argument>
        </arguments>
      </configuration>
      <goals>
        <goal>exec</goal>
      </goals>
    </execution>
    <execution>
      <id>install</id>
      <phase>install</phase>
      <configuration>
        <executable>./gradlew</executable>
        <arguments>
          <argument>install</argument>
        </arguments>
      </configuration>
      <goals>
        <goal>exec</goal>
      </goals>
    </execution>
  </executions>
</plugin>

See reasons at: https://stackoverflow.com/a/62971663/8650621

Felipe Desiderati
  • 2,414
  • 3
  • 24
  • 42