org.http4k.serverless.ApiGatewayRest.kt Maven / Gradle / Ivy

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Http4k Serverless support for AWS Lambda

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package org.http4k.serverless

import com.amazonaws.services.lambda.runtime.Context
import org.http4k.core.HttpHandler
import org.http4k.core.Method
import org.http4k.core.Request
import org.http4k.core.Response
import org.http4k.core.Uri
import org.http4k.core.toUrlFormEncoded

/**
 * Function loader for ApiGatewayRest Lambdas
 *
 * Use main constructor if you need to read ENV variables to make your HttpHandler and the AWS context
 */
class ApiGatewayRestFnLoader(input: AppLoaderWithContexts) :
    ApiGatewayFnLoader(ApiGatewayRestAwsHttpAdapter, input) {

    /**
     * Use this constructor if you need to read ENV variables to make your HttpHandler
     */
    constructor(input: AppLoader) : this(AppLoaderWithContexts { env, _ -> input(env) })

    /**
     * Use this constructor if you just want to convert a standard HttpHandler
     */
    constructor(input: HttpHandler) : this(AppLoader { input })
}

/**
 * This is the main entry point for lambda invocations using the REST payload format.
 * It uses the local environment to instantiate the HttpHandler which can be used
 * for further invocations.
 */
abstract class ApiGatewayRestLambdaFunction(appLoader: AppLoaderWithContexts) :
    AwsLambdaEventFunction(ApiGatewayRestFnLoader(appLoader)) {
    constructor(input: AppLoader) : this(AppLoaderWithContexts { env, _ -> input(env) })
    constructor(input: HttpHandler) : this(AppLoader { input })
}

object ApiGatewayRestAwsHttpAdapter : AwsHttpAdapter, Map> {
    private fun Map.toHttp4kRequest() =
        Request(
            Method.valueOf(getString("httpMethod") ?: error("method is invalid")),
            Uri.of(getString("path").orEmpty())
                .query((toMultiQueries() + toQueries()).distinct().toUrlFormEncoded())
        )
            .headers((toMultiHeaders() + toHeaders()).distinct())
            .body(toBody())

    override fun invoke(req: Map, ctx: Context) = runCatching { req.toHttp4kRequest() }

    override fun invoke(resp: Response) = mapOf(
        "statusCode" to resp.status.code,
        "headers" to resp.headers.toMap(),
        "body" to resp.bodyString(),
        "isBase64Encoded" to false
    )
}