Configuration

Basic Configuration

In order to enable Keeper on a particular variant, you must register the KeeperVariantMarker extension in AGP’s VariantBuilder API like so:

androidComponents {
  beforeVariants { builder ->
    if (shouldRunKeeperOnVariant()) {
      builder.optInToKeeper() // Helpful extension function
    }
  }
}

Or in Groovy

androidComponents {
  beforeVariants { builder ->
    if (shouldRunKeeperOnVariant(builder)) {
      builder.registerExtension(KeeperVariantMarker.class, KeeperVariantMarker.INSTANCE)
    }
  }
}

Keeper’s default behavior with no configuration effectively be a no-op, which isn’t what you want!

Advanced Configuration

Normally, your app variant’s minification task doesn’t depend on compilation of its corresponding androidTest variant. This means you can call assembleRelease and assembleAndroidTestRelease won’t inherently run. Keeper, however, changes this since it requires the compiled androidTest sources in order to correctly infer how they use APIs in the app variant. For a production build, you likely do want these “test-only” APIs removed if possible though. There are a few patterns to better control this behavior via Gradle property.

Simplest solution

The simplest solution is to add a new build type that extends release but is solely used for these tests. This way it’s identical to release in everything except the name.

android {
  buildTypes {
    staging {
      initWith release
    }
  }

  testBuildType = "staging"
}

Now Keeper will only wire for the StagingAndroidTest build type and the assembleRelease dependency tree will remain untouched.

This is the recommended solution, since builds that need this plugin likely already have custom logic in place for controlling testBuildType and it avoids messing with your normal release build. This is what we do internally at Slack as well.

Property-based Examples

Let’s assume an example command to build a production app with custom property productionBuild.

./gradlew :myapp:assembleRelease -PproductionBuild=true

Use the testBuildType option

If you avoid setting your testBuildType to your “release” build type in a production build, then Keeper won’t configure your release artifact to depend on test sources since your release variant would no longer be the testedVariant of any androidTest variants.

android {
  // ...

  if (hasProperty("productionBuild")) {
    testBuildType = "debug"
  } else {
    testBuildType = "release"
  }
}

Avoid applying the plugin entirely

This is probably the simplest approach, but not as dynamic as controlling the testBuildType.

if (!hasProperty("productionBuild")) {
  apply plugin: "com.slack.keeper"
}

Everyone’s project is different, so you should do whatever works for you! We’re open to suggestions of better ways to support configuration for this, so please do file issues if you have any proposals.

Custom R8 behavior

Keeper uses R8’s TraceReferences CLI under the hood for rules inference. By default it uses R8 version 3.2.78. If you want to customize what version is used, you can specify the dependency via the keeperR8 configuration. Note that these must be tags from R8’s r8-releases/raw maven repo.

dependencies {
  keeperR8 "com.android.tools:r8:x.y.z"
}

If you don’t want Keeper to automatically manage adding R8’s maven repo, you can set disable it via automaticR8RepoManagement. Note that you’ll need to manually add your own repo that the keeperR8 configuration mentioned above can resolve from.

keeper {
  automaticR8RepoManagement = false
}

If you want to add custom JVM arguments to its invocation (i.e. for debugging), you and set them via the keeper extension.

keeper {
  /**
   * Optional custom jvm arguments to pass into the R8 `PrintUses` execution. Useful if you want
   * to enable debugging in R8. Default is empty.
   *
   * Example: `listOf("-Xdebug", "-Xrunjdwp:transport=dt_socket,address=5005,server=y,suspend=y")`
   */
  r8JvmArgs = []
}

TraceReferences

Heads up!

TraceReferences is still experimental. Before reporting issues, please check if it’s an issue with Keeper or TraceReferences itself before filing. If it’s an issue with TraceReferences, please file on the Android issue tracker instead: https://issuetracker.google.com/issues/new?component=326788

TraceReferences is a new tool for generating Proguard rules based on one jar’s usage of classes in another jar. It is the formal successor and long-term replacement for the current PrintUses CLI that Keeper currently uses.

keeper {
  traceReferences {
    // Invoking this enables it!

    // Optional: extra arguments to pass to TraceReferences
    arguments.set(listOf("--map-diagnostics:MissingDefinitionsDiagnostic", "error", "info"))
  }
}

Note that this uses the R8 version controlled by the R8 version defined by the keeperR8 version. If you want to change it, set the version in keeperR8 to whichever version you want (must be higher than 3.0.9-dev).