This message was deleted.

Whenever you use a build service you have to make sure that it is wrapped in a

BuildServiceProvider

or Gradle will try to serialize it. The easiest way in a task to achieve this is:

class MyTask : DefaultTask() {
  lateinit var srv: Provider<MyService>
}

val srvProvider = gradle.shared...registerIfAbsent...

tasks.withType<MyTask>().configureEach {
  srv = srvProvider
  usesService(srvProvider)
}

Obviously both

lateinit

and

var

look ugly and might be misused, an alternative:

abstract class MyTask : DefaultTask() {
  abstract val srv: Property<Provider<MyService>>
}

val srvProvider = gradle.shared...registerIfAbsent...

tasks.withType<MyTask>().configureEach {
  srv.value(srvProvider).finalizeValue()
  usesService(srvProvider)
}

UNTESTED!

I tried both of these approaches and I get the same error in both cases…

What we've been doing was casting what is returned from

registerIfAbsent

to an actual

BuildServiceProvider

of the correct type. This allowed us to pass them on to worker actions. Maybe the same hack is necessary for configuration cache compatibility?

class MyBuildService : BuildService<MyBuildService.Parameters> {
  interface Parameters
}

typealias MyBuildServiceProvider = BuildServiceProvider<MyBuildService, MyBuildService.Parameters>

@Suppress("UNCHECKED_CAST")
val myServiceProvider = gradle.shared...registerIfAbsent... as MyBuildServiceProvider

class MyTask : DefaultTask() {
  val myBuildService: Property<MyBuildServiceProvider>
}

Again UNTESTED and written from the top of my head.

That doesn’t seem to work either for me:

Could not determine the dependencies of task ':services:notifications:notifications-dao:generateJooq'.
> Could not create task ':services:notifications:notifications-dao:migrateDbTask'.
   > Cannot set the value of task ':services:notifications:notifications-dao:migrateDbTask' property 'postgres' of type org.gradle.api.services.internal.BuildServiceProvider using a provider of type com.paxos.gradle.EmbeddedPostgresService.

Well, the

EmbeddedPostgresService

is not a

BuildServiceProvider

, what is it?

I have a

Provider<EmbeddedPostgresService>

from

registerIfAbsent

that I am casting to

Provider<BuildServiceProvider<EmbeddedPostgresService, EmbeddedPostgresService.Params>>

You need to cast it to

BuildServiceProvider<EmbeddedPostgresService, EmbeddedPostgresService.Params>

without the surrounding

Provider

. The signature of

registerIfAbsent

claims to return a plain

Provider

but it actually returns a

BuildServiceProvider

.

BINGO! success. Thank you very much @Fleshgrinder

🙂

I can’t help feeling this should have been documented somewhere….

What I don't understand is why it does not work without the cast. There should be some

instanceof

check somewhere for this, and that should evaluate to true as long as nobody turns that original

Provider

into something else.