quarkus: @Produce(EmptyBuildItem.class) not working

But since it exists and we’re relying on it… OK with that I guess, but let’s try to phase it out?

It does not exist yet 😉. Some code relies on it but it simply does not work.

I could not find any workaround to my issue. Previously, I was producing a FeatureBuildItem item and everything worked fine until I started using the OpenShift Container Image extension that needs a JAR build item. Here is where the build chain got crazy and I’m sure the issue is related to how the Kubernetes/OpenShift extensions are written.

Well, that’s something that needs to be investigated IMO…

So, my only hope was to somehow run my build step after the build is finished.

I don’t think that it’s possible.

I think it does make sense to create such a build item given some people were expecting it to work anyway.

As for the name, I think I would prefer AlwaysConsumedBuildItem.

This is actually a very good argument because EmptyBuildItem does not indicate “when” the build step will be executed. It should be probably a final item that will be consumable after the build step chain completes.

That raises an interesting question: do we really want the build step marked with @Produce(AlwaysConsumedBuildItem.class) to always be executed? E.g. I know we somehow consume a particular build item when generating dev services configuration; surely we don’t want to execute the build step then?

Maybe the name should be something like ExtensionCompleteBuildItem, to convey the meaning “the extension can only be considered complete once all those build items have been produced”? Then it would make sense to execute various checks in build steps that produce that build item.

I’m volunteering in working on this, just let me know if I should proceed

Gladly, thanks 😃

any hints are welcome 😃

You will have to:

• Add a guard here: https://github.com/quarkusio/quarkus/blob/2a41f877abb93112b5bd58d56165c2c06e64aa3a/core/builder/src/main/java/io/quarkus/builder/BuildStepBuilder.java#L236 to throw an exception when attempting to produce EmptyBuildItem (if EmptyBuildItem.class.equals(itemId.getType()) { throw ... })
• Agree on a name for the new build item with @mkouba (I suggest AlwaysConsumedBuildItem or ExtensionCompleteBuildItem, but I’m fine with anything else, really)
• Add that new build item somewhere (probably in the same package as EmptyBuildItem?)
• Change the message in https://github.com/quarkusio/quarkus/blob/2a41f877abb93112b5bd58d56165c2c06e64aa3a/core/builder/src/main/java/io/quarkus/builder/BuildStepBuilder.java#L204 to mention your new build item.
• Make sure that AlwaysConsumedBuildItem is indeed always consumed. @mkouba might have a hint about that; I believe initializing io.quarkus.builder.BuildChainBuilder#finalIds with the id of AlwaysConsumedBuildItem might do the trick.
• Add one or more tests to io.quarkus.builder.BasicTests
• Add a test somewhere in integration-tests/test-extension/extension/deployment/src/test. Maybe add a build step with @Produce(AlwaysConsumedBuildItem) to the test extension, have that build step set some static variable, and check in the test that the variable was set?
• Update the documentation in docs/src/main/asciidoc/writing-extensions.adoc to mention that new build item, probably in the same section that mentions EmptyBuildItem.