Features backed by Open rewrite recipes

[sdelamo]

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[sdelamo]

@alvarosanchez this PR has a lot of package imports changes because I extracted a micronaut-stater-sdk module. Please, ignore those for now.

I created a proof of concept of a starter feature consuming a OpenRewrite declarative recipe, in particular Gradle and Maven dependency recipes. See the RecipeDependencyFetcher api and its usage in the Mockito feature.

What do you think? It is still far from complete but this will allow us to define every feature dependencies with open rewrite recipes. We can then move to configuration recipes etc.

[alvarosanchez]

Note that there is org.openrewrite.java.dependencies.AddDependency which works for both Maven and Gradle.

Other than that, as far as I can see (the browser crashes with this gigantic PR), you're not really invoking OpenRewrite, but rather using its declarative recipe format as an alternative, internal way to define dependencies. Which, if I'm not mistaken, would end up going the same route of rendering Rocker templates.

I don't think we should do this. What I meant was to use OpenRewrite to actually perform changes to an existing project, via an additional command (eg mn add-feature). With this idea, features may (or may not) have, in addition to what they do today, a corresponding OpenRewrite recipe, that would only be used by such command. So that I can run mn add-feature mockito in my existing app. With this approach, we can gradually support more and more features in the add-feature command, without having to make deep changes in the existing Starter functionality

[sdelamo]

@alvarosanchez I think we are on the same page. I pushed an extra commit which hopefully clarifies the direction I am suggesting.

As you said, I want to support both use cases:

• Project Creation (create, create-app, ... commands),
• Project Modification (add-feature command).

Project Modification will invoke OpenRewrite recipes in an existing project. However, I have not implemented that yet. I have pushed a commit with an AddFeatureCommand class with a TODO where we will invoke OpenRewrite to execute the rules associated with features.

To gradually add features I have created a marker interface OpenRewriteFeature. Beans of type OpenRewriteFeature have OpenRewrite rules associated with them.

For me, the key is to define things only in a single place. That it is the reason why I created the RecipeDependencyFetcher API. To support defining the dependencies as open rewrite rules but transform those rules to Dependencyies to support the project creation use case. We will define the dependencies a feature adds on a single place - the OpenRewrite recipe associated with the feature.

NOTE: Currently, OpenRewrite does not support adding a gradle dependency to a Gradle file using the Kotlin DSL only the Groovy DSL.

Let me know if you think I am going in the right direction.

[alvarosanchez]

Convention seems to be using package names.

Also, I'd have a YML per main recipe, instead of having a huge rewrite.yml. OpenRewrite will detect them all within META-INF/rewrite.

[sdelamo]

not sure about using multiple files, we can decided about this later. micronaut resource loader api is not super flexible.

[alvarosanchez]

I suppose this also supports using Refaster and imperative recipes?

[sdelamo]

Yes, I have tried only with declarative recipes. But ideally, we should support every type of recipe.

[sdelamo]

maybe we could use a default convention such as io.micronaut.starter.feature.${featureName} to ensure unique name

[alvarosanchez]

@sdelamo amazing, then we are in agreement!

[sdelamo]

@alvarosanchez I have pushed a commit of an example of a feature contributing configuration. d71a1e7

We are going to need to create our own AddProperty implementation similar to AddSpringProperty, or AddQuarkusProperty as the AddProperty I used in my commit does not allow to provide a fileMatcher and in a Micronaut Application the property entry will be added to gradle.properties instead of application.properties in Micronaut gradle app.