CRD-Generator v2: Maven Plugin

[baloo42]

Is your enhancement related to a problem? Please describe

Because the CRD-Generator annotation processor is now deprecated, we need a replacement.
(see #5942)

Describe the solution you'd like

A CRD-Generator maven plugin could search for a top level annotation (or interface) and generate the CRDs using the CRD-Generator api.

Describe alternatives you've considered

No response

Additional context

• Jandex could be used to find and index the relevant annotations/classes.
• The following options should be supported:
  • Enable / disable parallel generation
  • CRD versions (v1, v1beta1)
    (TBD: There are thoughts to drop v1beta1 which makes this option irrelevant)
  • outputPath
  • header in output files
  • Allow to add additional labels
  • Allow to add additional annotations
  • Enable debug output

The also planned CRD-Generator gradle plugin (#5945) should support the same options.

[shawkins]

As suggested by @manusa we can just start with a clone of https://github.com/fabric8io/kubernetes-client/tree/main/java-generator/maven-plugin

[baloo42]

I'm working on a prototype atm...

[manusa]

Regarding the Maven Plugin implementation, I think it's OK, but we should strive to move any processing logic elsewhere so that it can be reused (for example for the Gradle Plugin). In the end, we want to have the plugins as just wrappers around functionality that's otherwise exposed.

Regarding the PR to Steven's branch, I'd try not to make that branch more complex and merge it ASAP as is. If we keep adding stuff to the branch, it'll get very hard to review.

[baloo42]

Regarding the PR to Steven's branch, I'd try not to make that branch more complex and merge it ASAP as is. If we keep adding stuff to the branch, it'll get very hard to review.

I'm totally fine with that decision. I just required a place to show the changes, so that I get initial feedback.

but we should strive to move any processing logic elsewhere so that it can be reused (for example for the Gradle Plugin)

The processing logic can be shared if we build an abstraction around org.codehaus.plexus.util.Scanner. But we need in this case another module shared by both plugins. If we put this into the crd-generator-api module it would introduce the jandex dependency to all subprojects.

IMHO it's probably the same amount of work. More complexity vs. a little bit duplicate code.

If we decide on a new intermediate module: What name should it have? indexer?

[manusa]

The processing logic can be shared if we build an abstraction around org.codehaus.plexus.util.Scanner

OK, I didn't see that we were leveraging Maven-specific capabilities to implement the mojo.

I think that if we implement first the Gradle plugin we'll be able to see if abstractions are needed or not. And if we need to follow a different path.

[baloo42]

Another approach would be to rely on a pre-existing jandex index which the user must provide. (e.g. by using the jandex-maven or gradle plugin). But I think it's not user friendly and should be only implemented as optional way.

I think that if we implement first the Gradle plugin we'll be able to see if abstractions are needed or not. And if we need to follow a different path.

Yes, let's start in parallel with the gradle plugin and see where it goes. I would try to implement it, but it will take some time as I haven't written any gradle plugins yet.

[manusa]

The ting is that regardless of the exposing method (Gradle plugin, Maven plugin, CLI main method) all of them should share the same processing logic to avoid any gaps across implementations. That's why I suggested in the first place to move processing logic elsewhere.

Maybe it must be easier to start first by exposing a public API method that can be exposed in a JBang script or a common CLI main method :)

[baloo42]

The ting is that regardless of the exposing method (Gradle plugin, Maven plugin, CLI main method) all of them should share the same processing logic to avoid any gaps across implementations.

👍

Then I think an intermediate module cannot be avoided if we don't want to introduce jandex to the api-v2 module.
The core problem remains the same. We have to scan class files, index them and find CustomResource classes.
Those classes must be loaded (including their dependencies) to work with Jackson's SchemaGenerator.

Or am I wrong?

I'll try to implement a CLI module next and try to find out what is required to share the code.

[baloo42]

The prototype can now be found here: baloo42#7

I extracted the shared code to a new module "crd-generator-collector" and refactored the maven plugin to use it.