This repository contains multiple Kotlin templates for OpenFaaS.

$ faas-cli template pull https://github.com/s1monw1/openfaas-kotlin
$ faas new --list

Languages available as templates:
- kotlin
- kotlin-http4k
- kotlin-quarkus-native

kotlin template

This template runs without any dependency and bootstraps its own com.sun.net.httpserver.HttpServer.

Trying the template

$ faas-cli template pull https://github.com/s1monw1/openfaas-kotlin
$ faas new --lang kotlin <fn-name>

Example usage

Example writing a successful message:

package com.openfaas.function

import com.openfaas.model.*

class Handler : IHandler {
    override fun handle(request: IRequest): IResponse {
        return Response(body = "Hello OpenFaas World")
    }
}

Example writing a custom status code

package com.openfaas.function

import com.openfaas.model.*

class Handler : IHandler {
    override fun handle(request: IRequest): IResponse {
        return Response(body = "Hello OpenFaas World", statusCode = 202)
    }
}

Example writing an error / failure.

package com.openfaas.function

import com.openfaas.model.*

class Handler : IHandler {
    override fun handle(request: IRequest): IResponse {
        return Response(body = "Error saying hello", statusCode = 500)
    }
}

The body will be written to the client along with a HTTP 500 status code.

kotlin-http4k template

This template is backed by http4k, a lightweight function http toolkit for Kotlin.

Trying the template

$ faas-cli template pull https://github.com/s1monw1/openfaas-kotlin
$ faas new --lang kotlin-http4k <fn-name>

Example usage

Example writing a successful message:

package com.openfaas.function

import org.http4k.core.*
import org.http4k.core.Status.Companion.OK

class Handler : HttpHandler {
    override fun invoke(request: Request): Response {
        return Response(OK).body("Hello OpenFaas World")
    }
}

Example writing a custom status code

import org.http4k.core.*
import org.http4k.core.Status.Companion.ACCEPTED

class Handler : HttpHandler {
    override fun invoke(request: Request): Response {
        return Response(ACCEPTED).body("Hello OpenFaas World")
    }
}

Example writing an error / failure.

import org.http4k.core.*
import org.http4k.core.Status.Companion.INTERNAL_SERVER_ERROR

class Handler : HttpHandler {
    override fun invoke(request: Request): Response {
        return Response(INTERNAL_SERVER_ERROR).body("Error saying hello")
    }
}

The body will be written to the client along with a HTTP 500 status code.

kotlin-quarkus-native template

This template is backed by Quarkus, a framework to build cloud-native JVM-based applications powered by GraalVM.

Trying the template

$ faas-cli template pull https://github.com/s1monw1/openfaas-kotlin
$ faas new --lang kotlin-quarkus-native <fn-name>