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IBM Cloud Functions reached end of life and this repository is no longer active.

For Apache OpenWhisk visit:https://github.com/apache/openwhisk.

⚠️ The Runtime for Kotlin is currently experimental. Feedback is welcome.⚠️

This runtime provides Kotlin running on the following OpenJDK/OpenJ9 image fromAdoptOpenJDK:

• adoptopenjdk/openjdk8-openj9:x86_64-ubuntu-jdk8u162-b12_openj9-0.8.0

The Runtime for Kotlin supports two APIs for creating actions:

1. JSON based.
   The action receives parameters as a JSON object and returns a JSON object, using theGoogle GSON library library.
2. Data Class based.
   The action receives parameters as a user defined data Class, and returns a user defined data Class.

The following shows how to build a "HelloWorld" action using the JSON API:

1. Create a file calledmain.kt containing:

   importcom.google.gson.JsonObjectfunmain(args:JsonObject) :JsonObject {val name= args.getAsJsonPrimitive("name").getAsString();val hello=JsonObject();    hello.addProperty("greeting","Hello"+ name+"!");return hello}

2. Compile the action into a JAR file:

   kotlinc -classpath ./gson-2.6.2.jar main.kt -d myAction.jar

This provides the action contained in myAction.jar, ready to be deployed and run.

The following shows how to build a "HelloWorld" action using the Data Class API:

1. Create a file calledmain.kt containing:

   data classUser (valname:String)data classHello (valgreeting:String)funmain(user:User) :Hello {val hello=Hello("Hello"+ user.name+"!")return hello}

2. Compile the action into a JAR file:

   kotlinc main.kt -d myAction.jar

This provides the action contained in myAction.jar, ready to be deployed and run.

The Kotlin action can be deployed for use as a Docker action using the following, works on any deployment of Apache OpenWhisk or IBM Cloud Functions"

bx wsk action update myAction myAction.jar --docker ibmfunctions/action-kotlin

This assumes that you have used the default file name ofmain.kt and the default main function name ofmain.

You can specify alternative package, file and main function names using the--main option towsk action update. For example:

• Using a file name ofhello.kt:

   bx wsk action update myAction myAction.jar --main"hello" --docker ibmfunctions/action-kotlin

• Using a main function name ofaction:

   bx wsk action update myAction myAction.jar --main"#action" --docker ibmfunctions/action-kotlin

• Using a file name ofhello.kt and a main function name ofaction:

   bx wsk action update myAction myAction.jar --main"hello#action" --docker ibmfunctions/action-kotlin

• Using a package ofmyfunctions with file name ofhello.kt and a main function name ofaction:

   bx wsk action update myAction myAction.jar --main"myfunctions.hello#action" --docker ibmfunctions/action-kotlin

The Kotlin action can be run in the same way as any other action. The following will execute the Hello World example with a parameter ofCloud Functions:

bx wsk action invoke myAction -b -p name"Cloud Functions"

This should return the following in theresponse section of the output:

"response": {"result": {"greeting":"Hello Cloud Functions!"        },"status":"success","success":true    }

Areas of future work for the Runtime for Kotlin include:

1. Async APIs.
   The Runtime for Kotlin currently only provides synchronous, blocking APIs, however it is well suited for asynchronous programming, and is used extensively in that way on Android.
2. Client SDK.
   The implementation of the data Class API makes it easy to share data type definitions with Kotlin clients. Having a client SDK that accepts data Classes when calling the action, particular for Android, would make adoption and usage much easier.

The following information describes how to build and deploy the Runtime for Kotlin from a local Git repository.

The following builds an image from the project:

./gradlew core:kotlin:distDocker

This will produce the imageibmfunctions/action-kotlin

The following builds an image, and pushes it to Dockerhub for use by OpenWhisk or IBM Cloud Functions:

docker login ./gradlew kotlin:distDocker -PdockerImagePrefix=$prefix-user -PdockerRegistry=docker.io

You can then create actions using your the image from dockerhub

wsk action update myAction myAction.jar --docker $user_prefix/action-kotlin

The$user_prefix is usually your dockerhub user id.

Install dependencies from the root directory on $OPENWHISK_HOME repository

./gradlew install

Using gradle to run all tests

./gradlew :tests:test

Using gradle to run some tests

./gradlew :tests:test --tests *ActionContainerTests*

Using IntelliJ:

• Import project as gradle project.
• Make sure working directory is root of the project/repo

Apache 2.0