Google Cloud Functions

The kroute-google-cloud-extension module provides adapters that bridge KRoute's interfaces with the Google Cloud Functions Framework API.

Installation

build.gradle.kts

dependencies {
    implementation("dev.catbit:kroute:1.0.2")
    implementation("dev.catbit:kroute-google-cloud-extension:1.0.2")
}

Usage

Create a class that implements com.google.cloud.functions.HttpFunction. Use the route extension from dev.catbit.kroute.google.cloud.extension.extensions to bridge the GCP types with KRoute automatically:

import com.google.cloud.functions.HttpFunction
import com.google.cloud.functions.HttpRequest
import com.google.cloud.functions.HttpResponse
import dev.catbit.kroute.google.cloud.extension.extensions.route
import dev.catbit.kroute.middleware.commons.CORSMiddleware
import dev.catbit.kroute.router.HttpFunctionRouter

class MyApi : HttpFunction {

    private val router = HttpFunctionRouter(
        functions = listOf(
            GetUsersFunction,
            GetUserFunction,
            CreateUserFunction,
            DeleteUserFunction
        ),
        preRoutingMiddlewares = listOf(CORSMiddleware),
        defaultMiddlewares = listOf(AuthMiddleware),
        onError = { e -> System.getLogger("MyApi").log(System.Logger.Level.ERROR, e) }
    )

    override fun service(request: HttpRequest, response: HttpResponse) {
        router.route(request, response) // (1)
    }
}

1. The route extension wraps the GCP HttpRequest and HttpResponse in KRoute's adapters automatically.

The GCP Functions Framework instantiates your class via reflection using its no-arg constructor. The router is initialized once and reused across requests.

How it works

The extension module provides lightweight adapters:

GCP type	KRoute adapter
com.google.cloud.functions.HttpRequest	GoogleCloudHttpRequest
com.google.cloud.functions.HttpResponse	GoogleCloudHttpResponse
com.google.cloud.functions.HttpRequest.HttpPart	GoogleCloudHttpPart

The route extension converts the GCP types transparently — your HttpFunction implementations never depend on GCP types directly.

Convenience extensions

You can also convert types individually:

import dev.catbit.kroute.google.cloud.extension.extensions.toHttpRequest
import dev.catbit.kroute.google.cloud.extension.extensions.toHttpResponse
import dev.catbit.kroute.google.cloud.extension.extensions.toHttpPart

val krouteRequest = gcpRequest.toHttpRequest()
val krouteResponse = gcpResponse.toHttpResponse()

Body and parts caching

GoogleCloudHttpRequest.body() and GoogleCloudHttpPart.body() are cached — the underlying InputStream is read at most once per request lifecycle. Subsequent calls to body() return the same ByteArray.

parts() is also lazily initialized and cached on first access.

Warning

Do not mix setBody(String) and setBody(ByteArray) on the same response. The Google Cloud Functions framework uses either the response Writer or OutputStream — calling both will throw an IllegalStateException.