Switch gRPC plugin to io.github.ascopes:protobuf-maven-plugin

[dsyer]

The samples at Spring gRPC have all been switched to this other plugin because the old one has fallen out of maintenance. It works on the command line right now, but Eclipse/VSCode users will want the hints to drive the build. See spring-io/initializr#1650

[mhalbritter]

A simple demo project with this fails with:

[INFO] Ignoring provided path /home/mhalbritter/Downloads/demo/src/main/protobuf as it does not appear to actually exist
[ERROR] No protobuf sources found. If this is unexpected, check your configuration and try again.
[ERROR] Generation failed - NO SOURCES: No valid protobuf sources were found. Check the build logs above for more details.

We need to add this to the configuration:

<sourceDirectories>
  <sourceDirectory>src/main/proto</sourceDirectory>
</sourceDirectories>

or we can change the generated empty directory from src/main/proto to src/main/protobuf. Which do you prefer?

And i think the whole dance with kr.motd.maven:os-maven-plugin is no longer necessary. If you remove binaryMavenPlugins.binaryMavenPlugin.classifier from the protobuf-maven-plugin configuration it still appears to work. Can we then remove that?

[dsyer]

I forgot about the proto file path. I think we should use the default, so (since we don’t ship samples from initializr with proto files) there’s nothing to do? Or can we create the empty directory as a hint?

I didn’t know the os classifier wasn’t needed. Maybe we should verify on all platforms? It seems to work for me on Linux.

UPDATE: I pushed some changes to align with comments above.

[dsyer]

N.B. I don't want to merge this yet until we either add an <?m2e ...?> hint (requires spring-io/initializr#1650) or the plugin gets a new release (3.2.4 will hopefully have the metadata OOTB).

[mhalbritter]

spring-io/initializr#1650 is in.

[dsyer]

So we can use that new API?

[mhalbritter]

Yeah, we can add processing instructions until the plugin authors release their new version.

[mhalbritter]

The maven plugin now uses src/main/protobuf, while the Gradle plugin (which is the offical com.google.protobuf one) expects the proto files at src/main/proto. Given that the existing documentation also uses src/main/proto, I suggest that we switch the Maven plugin to src/main/proto. I can take care of that change. OK for you?

[dsyer]

We switched the project samples already and I think the gradle builds still work. I’ll have to check. The docs can be changed of course.

UPDATE: it's a big mess. I will fix the samples in the gRPC project. I think you are right but I'm having some issues convincing the ascopes plugin to follow its configuration.

[mhalbritter]

This is what I currently have:

<configuration>
	<sourceDirectories>
		<sourceDirectory>src/main/proto</sourceDirectory>
	</sourceDirectories>
	<failOnMissingSources>false</failOnMissingSources>
	<protocVersion>${protobuf-java.version}</protocVersion>
	<binaryMavenPlugins>
		<binaryMavenPlugin>
			<groupId>io.grpc</groupId>
			<artifactId>protoc-gen-grpc-java</artifactId>
			<version>${grpc.version}</version>
			<options>jakarta_omit,@generated=omit</options>
		</binaryMavenPlugin>
	</binaryMavenPlugins>
</configuration>

[dsyer]

That should work for a standalone sample but it breaks if the app is not the top level in the Maven reactor. We can see if it can be fixed in the plugin (I opened an issue). I prefer to just use the default here for now,

[dsyer]

I added a new commit that changes the configuration in Gradle instead. You can decide how to do it.