Gradle

Gradle is used to build OpenWhisk. It does not need to be pre-installed as it installs itself using the Gradle Wrapper. To use it without installing, simply invoke the gradlew command at the root of the repository. You can also install gradle via apt on Ubuntu or brew on Mac. In the following we use gradle and gradlew as synonymous.

Usage

In general, project level properties are set via -P{propertyName}={propertyValue}. A task is called via gradle {taskName} and a subproject task is called via gradle :path:to:subproject:{taskName}. To run tasks in parallel, use the --parallel flag (Note: It's an incubating feature and might break stuff).

Build

To build all Docker images use gradle distDocker at the top level project, to build a specific component use gradle :core:controller:distDocker.

Project level options that can be used on distDocker:

• dockerImageName (required): The name of the image to build (e.g. whisk/controller)
• dockerHost (optional): The docker host to run commands on, default behaviour is docker's own DOCKER_HOST environment variable
• dockerRegistry (optional): The registry to push to
• dockerImageTag (optional, default 'latest'): The tag for the image
• dockerTimeout (optional, default 240): Timeout for docker operations in seconds
• dockerRetries (optional, default 3): How many times to retry docker operations
• dockerBinary (optional, default docker): The binary to execute docker commands

Test

To run tests one uses the test task. OpenWhisk consolidates tests into a single tests project. Hence the command to run all tests is gradle :tests:test.

It is possible to run specific tests using Gradle testfilters. For example gradle :tests:test --tests "your.package.name.TestClass.evenMethodName". Wildcard * may be used anywhere.

Build your own build.gradle

In Gradle, most of the tasks we use are default tasks provided by plugins in Gradle. The scala Plugin for example includes tasks, that are needed to build Scala projects. Moreover, Gradle is aware of Applications. The application Plugin provides tasks that are required to distribute a self-contained application. When application and scala are used in conjunction, they hook into each other and provide the tasks needed to distribute a Scala application. distTar for example compiles the Scala code, creates a jar containing the compiled classes and resources and creates a Tarball including that jar and all of its dependencies (defined in the dependencies section of build.gradle). It also creates a start-script which correctly sets the classpath for all those dependencies and starts the app.

In OpenWhisk, we want to distribute our application via Docker images. Hence we wrote a "plugin" that creates the task distDocker. That task will build an image from the Dockerfile that is located next to the build.gradle it is called from, for example Controller's Dockerfile and build.gradle are both located at core/controller.

If you want to create a new build.gradle for your component, simply put the Dockerfile right next to it and include docker.gradle by using

ext.dockerImageName = 'openwwhisk/{IMAGENAME}'
apply from: 'path/to/docker.gradle'

If your component needs to be build before you can build the image, make distDocker depend on any task needed to run before it, for example:

distDocker.dependsOn ':common:scala:distDocker', 'distTar'