v2: How to ensure Rust Gradle plugin can find cargo?

[thomaseizinger]

I am trying to use V2 to build an Android app that embeds a Rust library. NDK and everything is set up but now the build fails with "cargo: cannot find file or directory".

I've added Rust to the nativeBuildInputs but perhaps that isn't propagated all the way to the plugin? See https://github.com/firezone/firezone/pull/5647/files#diff-83ff257f624bb4fe99fc0695e3a9e038cb9eabfd5e4b0685cc1d6d765628f7a7R152-R163.

packages.firezone-android-debug =
  gradle2nix.builders.${system}.buildGradlePackage
    {
      pname = "firezone-android";
      # mark:next-android-version
      version = "1.1.2";
      src = ../../kotlin/android;
      lockFile = ../../kotlin/android/gradle.lock;
      gradleInstallFlags = [ "--stacktrace bundleDebug" ];

      NDK_HOME = "${android-sdk}/share/android-sdk/ndk/25.2.9519653";
      ANDROID_HOME = "${android-sdk}/share/android-sdk";
      ANDROID_SDK_ROOT = "${android-sdk}/share/android-sdk";
      JAVA_HOME = "${jdk.home}";

      nativeBuildInputs = [
        (pinnedRust.override
          {
            targets = [
              "aarch64-linux-android"
              "arm-linux-androideabi"
              "armv7-linux-androideabi"
              "i686-linux-android"
              "x86_64-linux-android"
            ];
          })
      ];
      overlays = aapt2LinuxJars;
    };

Help is much appreciated, I am still learning how Nix works :)

Build log:

@nix { "action": "setPhase", "phase": "unpackPhase" }
Running phase: unpackPhase
unpacking source archive /nix/store/d8f318gd60k9jklhm56xww9fnp0xd1mj-android
source root is android
@nix { "action": "setPhase", "phase": "patchPhase" }
Running phase: patchPhase
@nix { "action": "setPhase", "phase": "updateAutotoolsGnuConfigScriptsPhase" }
Running phase: updateAutotoolsGnuConfigScriptsPhase
@nix { "action": "setPhase", "phase": "configurePhase" }
Running phase: configurePhase
gradle: enabled parallel building
gradle: enabled parallel checking
gradle: enabled parallel installing
@nix { "action": "setPhase", "phase": "buildPhase" }
Running phase: buildPhase
@nix { "action": "setPhase", "phase": "installPhase" }
Running phase: installPhase
gradleInstallPhase flags: --console=plain --stacktrace bundleDebug --parallel --max-workers 16

Welcome to Gradle 8.7!

Here are the highlights of this release:
 - Compiling and testing with Java 22
 - Cacheable Groovy script compilation
 - New methods in lazy collection properties

For more details see https://docs.gradle.org/8.7/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)
> Task :app:preBuild UP-TO-DATE
> Task :app:preDebugBuild UP-TO-DATE
> Task :generateLinkerWrapper
> Task :app:generateDebugResValues
> Task :app:injectCrashlyticsMappingFileIdDebug
> Task :app:processDebugGoogleServices
> Task :app:mapDebugSourceSetPaths
> Task :app:generateDebugResources
> Task :app:createDebugCompatibleScreenManifests
> Task :app:extractDeepLinksDebug
> Task :app:processDebugMainManifest
> Task :app:processDebugManifest
> Task :app:processApplicationManifestDebugForBundle
> Task :app:mergeDebugResources
> Task :app:checkDebugAarMetadata
> Task :app:packageDebugResources
> Task :app:mergeDebugShaders
> Task :app:compileDebugShaders NO-SOURCE
> Task :app:generateDebugAssets UP-TO-DATE
> Task :app:parseDebugLocalResources
> Task :app:mergeDebugAssets FROM-CACHE
> Task :app:desugarDebugFileDependencies
> Task :app:dataBindingMergeDependencyArtifactsDebug
> Task :app:generateDebugBuildConfig
> Task :app:dataBindingGenBaseClassesDebug
> Task :app:generateSafeArgsDebug
> Task :app:javaPreCompileDebug
> Task :app:checkDebugDuplicateClasses
> Task :app:cargoBuildArm FAILED
> Task :app:processDebugManifestForPackage

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:cargoBuildArm'.
> A problem occurred starting process 'command 'cargo''

* Try:
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:cargoBuildArm'.
	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.lambda$executeIfValid$1(ExecuteActionsTaskExecuter.java:130)
	at org.gradle.internal.Try$Failure.ifSuccessfulOrElse(Try.java:282)
	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeIfValid(ExecuteActionsTaskExecuter.java:128)
	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:116)
	at org.gradle.api.internal.tasks.execution.FinalizePropertiesTaskExecuter.execute(FinalizePropertiesTaskExecuter.java:46)
	at org.gradle.api.internal.tasks.execution.ResolveTaskExecutionModeExecuter.execute(ResolveTaskExecutionModeExecuter.java:51)
	at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:57)
	at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:74)
	at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:36)
	at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:77)
	at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:55)
	at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:52)
	at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:200)
	at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:195)
	at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
	at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
	at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:157)
	at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
	at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:73)
	at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:52)
	at org.gradle.execution.plan.LocalTaskNodeExecutor.execute(LocalTaskNodeExecutor.java:42)
	at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:331)
	at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:318)
	at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.lambda$execute$0(DefaultTaskExecutionGraph.java:314)
	at org.gradle.internal.operations.CurrentBuildOperationRef.with(CurrentBuildOperationRef.java:80)
	at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:314)
	at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:303)
	at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.execute(DefaultPlanExecutor.java:463)
	at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.run(DefaultPlanExecutor.java:380)
	at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
	at org.gradle.internal.concurrent.AbstractManagedExecutor$1.run(AbstractManagedExecutor.java:47)
Caused by: org.gradle.process.internal.ExecException: A problem occurred starting process 'command 'cargo''
	at org.gradle.process.internal.DefaultExecHandle.execExceptionFor(DefaultExecHandle.java:241)
	at org.gradle.process.internal.DefaultExecHandle.setEndStateInfo(DefaultExecHandle.java:218)
	at org.gradle.process.internal.DefaultExecHandle.failed(DefaultExecHandle.java:396)
	at org.gradle.process.internal.ExecHandleRunner.lambda$run$3(ExecHandleRunner.java:102)
	at org.gradle.internal.operations.CurrentBuildOperationRef.with(CurrentBuildOperationRef.java:80)
	at org.gradle.process.internal.ExecHandleRunner.run(ExecHandleRunner.java:101)
	at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
	at org.gradle.internal.concurrent.AbstractManagedExecutor$1.run(AbstractManagedExecutor.java:47)
Caused by: net.rubygrapefruit.platform.NativeException: Could not start 'cargo'
	at net.rubygrapefruit.platform.internal.DefaultProcessLauncher.start(DefaultProcessLauncher.java:27)
	at net.rubygrapefruit.platform.internal.WrapperProcessLauncher.start(WrapperProcessLauncher.java:36)
	at org.gradle.process.internal.ExecHandleRunner.startProcess(ExecHandleRunner.java:122)
	at org.gradle.process.internal.ExecHandleRunner.lambda$run$0(ExecHandleRunner.java:80)
	at org.gradle.internal.operations.CurrentBuildOperationRef.with(CurrentBuildOperationRef.java:80)
	at org.gradle.process.internal.ExecHandleRunner.run(ExecHandleRunner.java:79)
	... 2 more
Caused by: java.io.IOException: Cannot run program "cargo" (in directory "/rust/connlib/clients/android"): error=2, No such file or directory
	at net.rubygrapefruit.platform.internal.DefaultProcessLauncher.start(DefaultProcessLauncher.java:25)
	... 7 more
Caused by: java.io.IOException: error=2, No such file or directory
	... 8 more


Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.7/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

BUILD FAILED in 33s
26 actionable tasks: 25 executed, 1 from cache

[thomaseizinger]

Found something that got me further: https://github.com/mozilla/rust-android-gradle?tab=readme-ov-file#specifying-paths-to-sub-commands-python-cargo-and-rustc.

We can specify: RUST_ANDROID_GRADLE_CARGO_COMMAND and RUST_ANDROID_GRADLE_RUSTC_COMMAND.