Task configuration depends on task output

Help/Discuss
1

I have two tasks, each downloading a file from a url.
They both have a @Input Property<String> url and a @OutputFile Property<Path> output.
The configuration is as follows:

task1.configure {
  it.url.set 'https://www.website.com'
  it.output.set somePath
}
task2.configure {
  it.url.set task1.flatMap({ it.output.map { getUrl(it) } })
  it.output.set someOtherPath
}

Now task2 crashes if task1 hasn’t run first.
This is because the inputs of task2 are resolved before task1 has run.
How do I solve this?

2

What is the actual error you’re getting? I’m unable to reproduce any issues with the following (I was using Gradle 6.8.3):

abstract class X extends DefaultTask
{
    @Input abstract Property<String> getUrl()
    @OutputFile abstract Property<File> getOutput()
    @TaskAction void doWork() { println "${url.get()} -> ${output.get()}" }
}
def t1 = tasks.register( 'task1', X ) {
  it.url.set 'https://www.website.com'
  it.output.set file( 'abc' )
}
tasks.register( 'task2', X ) {
  it.url.set t1.flatMap( { it.output.map { "https://${it}" } } )
  it.output.set file( 'def' )
}

Results:

$ ./gradlew task2
> Task :task1
https://www.website.com -> C:\Users\oes\forum-test\abc
> Task :task2
https://C:\Users\oes\forum-test\abc -> C:\Users\oes\forum-test\def
3

Apparently I was wrong about the actual cause of the issue.
Here is a modified version of my code that causes the issue.

it.url.set downloadManifest.flatMap({
  project.objects.property(Manifest).convention(
    it.output.map {
      it.newReader().withReader {
        Utils.GSON.fromJson it, Manifest
      }
    }
  ).flatMap({values.version.map {s -> it.getUrl(s).toString() }})
})

The exception:

org.gradle.api.internal.tasks.TaskDependencyResolveException: Could not determine the dependencies of task ':downloadVersionJson'.
        at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext.getDependencies(CachingTaskDependencyResolveContext.java:71)
        at org.gradle.execution.plan.TaskDependencyResolver.resolveDependenciesFor(TaskDependencyResolver.java:46)
        at org.gradle.execution.plan.LocalTaskNode.getDependencies(LocalTaskNode.java:155)
        at org.gradle.execution.plan.LocalTaskNode.resolveDependencies(LocalTaskNode.java:123)
        at org.gradle.execution.plan.DefaultExecutionPlan.doAddNodes(DefaultExecutionPlan.java:171)
        at org.gradle.execution.plan.DefaultExecutionPlan.addEntryTasks(DefaultExecutionPlan.java:135)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph.addEntryTasks(DefaultTaskExecutionGraph.java:160)
        at org.gradle.execution.TaskNameResolvingBuildConfigurationAction.configure(TaskNameResolvingBuildConfigurationAction.java:49)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.configure(DefaultBuildConfigurationActionExecuter.java:55)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.access$000(DefaultBuildConfigurationActionExecuter.java:26)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter$1.proceed(DefaultBuildConfigurationActionExecuter.java:63)
        at org.gradle.execution.DefaultTasksBuildExecutionAction.configure(DefaultTasksBuildExecutionAction.java:45)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.configure(DefaultBuildConfigurationActionExecuter.java:55)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.access$000(DefaultBuildConfigurationActionExecuter.java:26)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter$1.proceed(DefaultBuildConfigurationActionExecuter.java:63)
        at org.gradle.execution.ExcludedTaskFilteringBuildConfigurationAction.configure(ExcludedTaskFilteringBuildConfigurationAction.java:48)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.configure(DefaultBuildConfigurationActionExecuter.java:55)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.lambda$select$0(DefaultBuildConfigurationActionExecuter.java:42)
        at org.gradle.internal.Factories$1.create(Factories.java:31)
        at org.gradle.api.internal.project.DefaultProjectStateRegistry.withMutableStateOfAllProjects(DefaultProjectStateRegistry.java:141)
        at org.gradle.api.internal.project.DefaultProjectStateRegistry.withMutableStateOfAllProjects(DefaultProjectStateRegistry.java:128)
        at org.gradle.execution.DefaultBuildConfigurationActionExecuter.select(DefaultBuildConfigurationActionExecuter.java:40)
        at org.gradle.initialization.DefaultTaskExecutionPreparer.prepareForTaskExecution(DefaultTaskExecutionPreparer.java:38)
        at org.gradle.initialization.BuildOperationFiringTaskExecutionPreparer$CalculateTaskGraph.populateTaskGraph(BuildOperationFiringTaskExecutionPreparer.java:117)
        at org.gradle.initialization.BuildOperationFiringTaskExecutionPreparer$CalculateTaskGraph.run(BuildOperationFiringTaskExecutionPreparer.java:68)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$1.execute(DefaultBuildOperationRunner.java:29)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$1.execute(DefaultBuildOperationRunner.java:26)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$3.execute(DefaultBuildOperationRunner.java:75)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$3.execute(DefaultBuildOperationRunner.java:68)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:153)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:68)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.run(DefaultBuildOperationRunner.java:56)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.lambda$run$1(DefaultBuildOperationExecutor.java:71)
        at org.gradle.internal.operations.UnmanagedBuildOperationWrapper.runWithUnmanagedSupport(UnmanagedBuildOperationWrapper.java:45)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:71)
        at org.gradle.initialization.BuildOperationFiringTaskExecutionPreparer.prepareForTaskExecution(BuildOperationFiringTaskExecutionPreparer.java:56)
        at org.gradle.initialization.DefaultGradleLauncher.prepareTaskExecution(DefaultGradleLauncher.java:233)
        at org.gradle.initialization.DefaultGradleLauncher.doClassicBuildStages(DefaultGradleLauncher.java:167)
        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:148)
        at org.gradle.initialization.DefaultGradleLauncher.executeTasks(DefaultGradleLauncher.java:124)
        at org.gradle.internal.invocation.GradleBuildController$1.create(GradleBuildController.java:72)
        at org.gradle.internal.invocation.GradleBuildController$1.create(GradleBuildController.java:67)
        at org.gradle.internal.work.DefaultWorkerLeaseService.withLocks(DefaultWorkerLeaseService.java:213)
        at org.gradle.internal.invocation.GradleBuildController.doBuild(GradleBuildController.java:67)
        at org.gradle.internal.invocation.GradleBuildController.run(GradleBuildController.java:56)
        at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:31)
        at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
        at org.gradle.launcher.exec.BuildOutcomeReportingBuildActionRunner.run(BuildOutcomeReportingBuildActionRunner.java:63)
        at org.gradle.tooling.internal.provider.ValidatingBuildActionRunner.run(ValidatingBuildActionRunner.java:32)
        at org.gradle.tooling.internal.provider.FileSystemWatchingBuildActionRunner.run(FileSystemWatchingBuildActionRunner.java:77)
        at org.gradle.launcher.exec.BuildCompletionNotifyingBuildActionRunner.run(BuildCompletionNotifyingBuildActionRunner.java:41)
        at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner$3.call(RunAsBuildOperationBuildActionRunner.java:49)
        at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner$3.call(RunAsBuildOperationBuildActionRunner.java:44)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:200)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:195)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$3.execute(DefaultBuildOperationRunner.java:75)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$3.execute(DefaultBuildOperationRunner.java:68)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:153)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:68)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:62)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.lambda$call$2(DefaultBuildOperationExecutor.java:76)
        at org.gradle.internal.operations.UnmanagedBuildOperationWrapper.callWithUnmanagedSupport(UnmanagedBuildOperationWrapper.java:54)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:76)
        at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner.run(RunAsBuildOperationBuildActionRunner.java:44)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.lambda$execute$0(InProcessBuildActionExecuter.java:54)
        at org.gradle.composite.internal.DefaultRootBuildState.run(DefaultRootBuildState.java:86)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:53)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:29)
        at org.gradle.launcher.exec.BuildTreeScopeLifecycleBuildActionExecuter.lambda$execute$0(BuildTreeScopeLifecycleBuildActionExecuter.java:33)
        at org.gradle.internal.buildtree.BuildTreeState.run(BuildTreeState.java:49)
        at org.gradle.launcher.exec.BuildTreeScopeLifecycleBuildActionExecuter.execute(BuildTreeScopeLifecycleBuildActionExecuter.java:32)
        at org.gradle.launcher.exec.BuildTreeScopeLifecycleBuildActionExecuter.execute(BuildTreeScopeLifecycleBuildActionExecuter.java:27)
        at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:104)
        at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:55)
        at org.gradle.tooling.internal.provider.SubscribableBuildActionExecuter.execute(SubscribableBuildActionExecuter.java:64)
        at org.gradle.tooling.internal.provider.SubscribableBuildActionExecuter.execute(SubscribableBuildActionExecuter.java:37)
        at org.gradle.tooling.internal.provider.SessionScopeLifecycleBuildActionExecuter.lambda$execute$0(SessionScopeLifecycleBuildActionExecuter.java:54)
        at org.gradle.internal.session.BuildSessionState.run(BuildSessionState.java:67)
        at org.gradle.tooling.internal.provider.SessionScopeLifecycleBuildActionExecuter.execute(SessionScopeLifecycleBuildActionExecuter.java:50)
        at org.gradle.tooling.internal.provider.SessionScopeLifecycleBuildActionExecuter.execute(SessionScopeLifecycleBuildActionExecuter.java:36)
        at org.gradle.tooling.internal.provider.GradleThreadBuildActionExecuter.execute(GradleThreadBuildActionExecuter.java:36)
        at org.gradle.tooling.internal.provider.GradleThreadBuildActionExecuter.execute(GradleThreadBuildActionExecuter.java:25)
        at org.gradle.tooling.internal.provider.StartParamsValidatingActionExecuter.execute(StartParamsValidatingActionExecuter.java:59)
        at org.gradle.tooling.internal.provider.StartParamsValidatingActionExecuter.execute(StartParamsValidatingActionExecuter.java:31)
        at org.gradle.tooling.internal.provider.SessionFailureReportingActionExecuter.execute(SessionFailureReportingActionExecuter.java:55)
        at org.gradle.tooling.internal.provider.SessionFailureReportingActionExecuter.execute(SessionFailureReportingActionExecuter.java:41)
        at org.gradle.tooling.internal.provider.SetupLoggingActionExecuter.execute(SetupLoggingActionExecuter.java:47)
        at org.gradle.tooling.internal.provider.SetupLoggingActionExecuter.execute(SetupLoggingActionExecuter.java:31)
        at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:65)
        at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:37)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:39)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:29)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.RequestStopIfSingleUsedDaemon.execute(RequestStopIfSingleUsedDaemon.java:35)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.create(ForwardClientInput.java:78)
        at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.create(ForwardClientInput.java:75)
        at org.gradle.util.Swapper.swap(Swapper.java:38)
        at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:75)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.LogAndCheckHealth.execute(LogAndCheckHealth.java:55)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:63)
        at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:37)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:84)
        at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:37)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
        at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:52)
        at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:297)
        at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
        at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
        at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
Caused by: java.lang.reflect.UndeclaredThrowableException
        at com.sun.proxy.$Proxy51.transform(Unknown Source)
        at org.gradle.api.internal.provider.TransformBackedProvider.mapValue(TransformBackedProvider.java:73)
        at org.gradle.api.internal.provider.TransformBackedProvider.calculateOwnValue(TransformBackedProvider.java:65)
        at org.gradle.api.internal.provider.AbstractMinimalProvider.calculateValue(AbstractMinimalProvider.java:103)
        at org.gradle.api.internal.provider.MappingProvider.calculateOwnValue(MappingProvider.java:55)
        at org.gradle.api.internal.provider.AbstractMinimalProvider.calculateValue(AbstractMinimalProvider.java:103)
        at org.gradle.api.internal.provider.DefaultProperty.calculateValueFrom(DefaultProperty.java:128)
        at org.gradle.api.internal.provider.DefaultProperty.calculateValueFrom(DefaultProperty.java:25)
        at org.gradle.api.internal.provider.AbstractProperty.doCalculateValue(AbstractProperty.java:133)
        at org.gradle.api.internal.provider.AbstractProperty.calculateOwnValue(AbstractProperty.java:127)
        at org.gradle.api.internal.provider.AbstractMinimalProvider.calculateValue(AbstractMinimalProvider.java:103)
        at org.gradle.api.internal.provider.FlatMapProvider.backingProvider(FlatMapProvider.java:62)
        at org.gradle.api.internal.provider.FlatMapProvider.getProducer(FlatMapProvider.java:71)
        at org.gradle.api.internal.provider.FlatMapProvider.getProducer(FlatMapProvider.java:71)
        at org.gradle.api.internal.provider.MappingProvider.getProducer(MappingProvider.java:45)
        at org.gradle.api.internal.provider.AbstractProperty.getProducer(AbstractProperty.java:178)
        at org.gradle.api.internal.provider.AbstractMinimalProvider.visitDependencies(AbstractMinimalProvider.java:125)
        at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext$TaskGraphImpl.getNodeValues(CachingTaskDependencyResolveContext.java:114)
        at org.gradle.internal.graph.CachingDirectedGraphWalker$GraphWithEmptyEdges.getNodeValues(CachingDirectedGraphWalker.java:213)
        at org.gradle.internal.graph.CachingDirectedGraphWalker.doSearch(CachingDirectedGraphWalker.java:121)
        at org.gradle.internal.graph.CachingDirectedGraphWalker.findValues(CachingDirectedGraphWalker.java:73)
        at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext.getDependencies(CachingTaskDependencyResolveContext.java:69)
        ... 114 more
Caused by: java.nio.file.NoSuchFileException: C:\Users\ntvan\.gradle\caches\myPlugin\manifest.json
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at nl.striderofthewest.fg.FGPlugin$_apply_closure7$_closure11$_closure13.doCall(FGPlugin.groovy:115)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        ... 136 more