How to create a quarkus uber-jar with a custom shading or configuration?

[Mario Fusco]

Hi all,

Premise: Drools, that as you know is internally used by Kogito, is made of many (optional) modules and the biggest part of them contains a file called META-INF/kie.conf describing all the services provided by that module. When it is necessary to create an uber-jar, the content of all the kie.conf files included in the drools modules required by the user's project have to be concatenated into a single file and to this purpose we suggest to use the maven-shade-plugin as for instance documented here.

My problem is that I couldn't find a way to make the shade-plugin to integrate or cooperate in any way with the Quarkus way of creating an uber-jar. In fact without the shade-plugin and using the application property

  quarkus.package.type=uber-jar

Quarkus creates a jar that, as expected, contains a kie.conf file that is randomly picked among the many ones available in the many imported Drools modules. Adding the shade-plugin doesn't help because doing so the jar packaging fails with an error like the following:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:3.2.0:shade (default) on project optaplanner-solver-factory-issue: Failed to create shaded artifact, project main artifact does not exist. -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:3.2.0:shade (default) on project optaplanner-solver-factory-issue: Failed to create shaded artifact, project main artifact does not exist.

[ERROR] The project main artifact does not exist. This could have the following
[ERROR] reasons:
[ERROR] - You have invoked the goal directly from the command line. This is not
[ERROR]   supported. Please add the goal to the default lifecycle via an
[ERROR]   <execution> element in your POM and use "mvn package" to have it run.
[ERROR] - You have bound the goal to a lifecycle phase before "package". Please
[ERROR]   remove this binding from your POM such that the goal will be run in
[ERROR]   the proper phase.
[ERROR] - You removed the configuration of the maven-jar-plugin that produces the main artifact.

I believe that what's happening in this case is that Quarkus runs before the shading, replacing the actual jar with the -runner one so that the shading-plugin is no longer able to find the jar to be shaded. Unfrotunately the shade-plugin doesn't allow to specify a different name for the jar to be shaded. I also tried to change the name of the uber-jar produced by Quarkus as explained here, to restore the name expected by the shade-plugin, but Quarkus always appends (a bit arbitrarily imo) the -runner suffix to the name of the requested file name. 

Finally, in a desperate attempt to make this work, I manually created the concatenated META-INF/kie.conf file and added it to the user project, but still the Quarkus uber-jar creation process is ignoring it and randomly picking one from the imported Drools modules. This very likely implies that even if I had a way to make Kogito to programmatically generate that concatenated conf file it would be still very possible for Quakrus to ignore it and take a different one.

Can you suggest any other workaround to solve this problem? More in general is there any plan to make the Quarkus uber-jar creation a bit more flexible/configurable and cover similar use cases?

Thanks for help,

Mario

[Alexey Loubyansky]

Have you tried using Quarkus build items for that?

E.g. PackageTypeBuildItem or PackageConfig can be used to check whether the package type is the uber-jar. If it's the uber-jar you could try producing the following build items:

1) UberJarIgnoredResourceBuildItem could be used to filter out resources (e.g. the META-INF/kie.conf files) during the packaging phase;

2) GeneratedResourceBuildItem representing the merged META-INF/kie.conf file (which you could generated by looking for 'META-INF/kie.conf' on the classpath or iterating through the runtime dependencies CurateOutcomeBuildItem.getEffectiveAppModel().getUserDependencies()).

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[Alexey Loubyansky]

On Tue, Jul 6, 2021 at 2:10 PM Alexey Loubyansky <alexey.l...@redhat.com> wrote:

Have you tried using Quarkus build items for that?

E.g. PackageTypeBuildItem or PackageConfig can be used to check whether the package type is the uber-jar. If it's the uber-jar you could try producing the following build items:

1) UberJarIgnoredResourceBuildItem could be used to filter out resources (e.g. the META-INF/kie.conf files) during the packaging phase;

2) GeneratedResourceBuildItem representing the merged META-INF/kie.conf file (which you could generated by looking for 'META-INF/kie.conf' on the classpath or iterating through the runtime dependencies CurateOutcomeBuildItem.getEffectiveAppModel().getUserDependencies()).

It may look confusing to ignore and generate the same path (META-INF/kie.conf) at the same time but it looks like it should work.

[Alexey Loubyansky]

There is actually code performing concatenation already for a couple of known resources. But it's not configurable at this point. It makes sense to expose a config for it so you could simply produce something like ConcatenateResourcesBuildItem("META-INF/kie.conf") in case the packaging type is uber-jar.

[George Gastaldi]

The solution is to produce a GeneratedResourceBuildItem or a UberJarMergedResourceBuildItem in your extension.

See https://github.com/quarkusio/quarkus/blob/main/core/test-extension/deployment/src/main/java/io/quarkus/extest/deployment/UberJarConfigBuildStep.java for an example

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[Alexey Loubyansky]

Oh, it is configurable, nice.

[Mario Fusco]

Thanks a lot for your suggestions Alexey and George.

I wasn't aware of that UberJarMergedResourceBuildItem, I'll try to use it in the kogito extension and keep you updated.

Thanks again,

Mario

[George Gastaldi]

You're welcome!

For the record, use UberJarMergedResourceBuildItem if the target file can be concatenated (like a properties file), otherwise use GeneratedResourceBuildItem