Switching from Maven to Gradle Shadow

[willis7]

How can I do the following in Gradle Shadow:

<configuration>
       <transformers>
              <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
              <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                     <mainClass>com.my.Application</mainClass>
              </transformer>
       </transformers>
</configuration>

I can see you have the ManifestResourceTransformer, but I cant see a ServiceResourceTransformer. If you could supply a snippet for the usecase above that would be very handy! Kind regards, Sion

[johnrengelman]

https://github.com/johnrengelman/shadow/blob/master/README.md#merging-service-files

[willis7]

Hi John,

Sorry if I'm being really dim. I've looked at the source and the readme you linked, but it doesn't look like that answers my original question.

So the source shows me the following:

ShadowJar mergeServiceFiles(Closure configureClosure) {
        transform(ServiceFileTransformer, configureClosure)
    }

So, that only applies a single transform. My example has 2 transforms, and the addition of the mainClass. Thats what has me stumped with your implementation of the plugin.

Regards,
Sion

[johnrengelman]

There's a separate ManifestResourceTransformer: https://github.com/johnrengelman/shadow/blob/master/src/main/groovy/com/github/jengelman/gradle/plugins/shadow/transformers/ManifestResourceTransformer.groovy

And you would use this: https://github.com/johnrengelman/shadow/blob/master/README.md#transforming-resources

[willis7]

Ahh ok, so the following should do it:

shadowJar {
  mergeServiceFiles()
  transform(ManifestResourceTransformer) {
    mainClass = com.my.Application
  }
}

I thought I had tried that with no joy. Will try again.

[johnrengelman]

mainClass takes a String though. So

shadowJar {
  mergeServiceFiles()
  transform(ManifestResourceTransfomer) {
    mainClass = 'com.my.Application'
  }
}

Since shadowJar is just a Jar task, you could also use this syntax (which is what I generally prefer):

shadowJar {
  mergeServiceFiles()
  manifest {
    attributes 'Main-Class': 'com.my.Application'
  }
}

[willis7]

Thanks! your solution is much more elegant and intuitive. I appreciate your help and kudos on the plugin, I've certainly noticed a speed bonus over the other alternatives. Many thanks!