Build and publish muzzle check plugin separately

[iNikem]

When trying to run muzzle in parallel in GHA, building projects buildSrc takes 2/3 of each task execution. This is total waste of time. Should build it once, publish and consume externally.

[iNikem]

Damn :( muzzle plugin, living inside buildSrc, reaches to javaagent-bootstrap and javaagent-tooling to grab their runtime classpaths :( This makes extracting plugin almost impossible :(

[pavolloffay]

Is there any way how it could be done? I am happy to help with this.

[iNikem]

I don't know one right now.

[pavolloffay]

@iNikem Is this the problem?

opentelemetry-java-instrumentation/buildSrc/src/main/groovy/MuzzlePlugin.groovy

Lines 62 to 63 in 4624584

	def bootstrapProject = project.rootProject.getChildProjects().get('javaagent-bootstrap')
	def toolingProject = project.rootProject.getChildProjects().get('javaagent-tooling')

I would like to use the muzzle plugin in a custom build with added instrumentations. The muzzle would be very helpful there.

[iNikem]

Yes, this is it.

[pavolloffay]

Commenting from #1408

The muzzle task could expose a property to configure classpath with javaagent-tooling and javaagent-bootstrap artifacts. E.g something similar to what ByteBuddy plugin does
https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/master/gradle/instrumentation.gradle#L36

  byteBuddy {
    transformation {
      tasks = ['compileJava', 'compileScala', 'compileKotlin']
      plugin = 'io.opentelemetry.javaagent.tooling.muzzle.collector.MuzzleCodeGenerationPlugin'
      classPath = project(':javaagent-tooling').configurations.instrumentationMuzzle + configurations.runtimeClasspath + sourceSets.main.output
    }
  }

[mateuszrzeszutek]

A bit of clarification: this issue concerns the muzzle check plugin (MuzzlePlugin currently), not the muzzle compile one - there's a separate issue for the muzzle compile plugin extraction.

[iNikem]

Done