deno runtime for aws lambda

lambda-runtime.ts

import type { Handler } from "packages/lib/types/Handler.ts";
import { shutdownBackend } from "packages/events/mod.ts";
// import { createLogger } from "packages/logs/mod.ts";
import { APIGatewayEvent } from "packages/lib/types/aws.ts";
function createLogger(..._args: Array<string>) {
  return console.log;
}
const log = createLogger("lambda:runtime", "debug");
const logInfo = createLogger("lambda:runtime", "info");
const logError = createLogger("lambda:runtime", "error");

let abortController = new AbortController();
let isShuttingDown = false;

async function handleShutdown() {
  if (isShuttingDown) return;
  isShuttingDown = true;
  logInfo("Shutting down gracefully...");

  // Abort the ongoing fetch operation

  abortController.signal.onabort = async () => {
    logInfo("killed request");
    await Deno.writeTextFile(
      "/tmp/.restart",
      `${Date.now()}`,
    );
  };
  abortController.abort();
}

globalThis.addEventListener("unload", handleShutdown);

const AWS_LAMBDA_RUNTIME_API = Deno.env.get(
  "AWS_LAMBDA_RUNTIME_API",
);

async function respond<T>(
  lambdaRuntimeIncomingRequest: Response,
  handler: Handler<T>,
) {
  const requestId = lambdaRuntimeIncomingRequest.headers.get(
    "Lambda-Runtime-Aws-Request-Id",
  );
  if (!requestId) throw new Error("Missing Lambda-Runtime-Aws-Request-Id");
  log("debug", "Processing request", requestId);
  let responseBody = {
    statusCode: 500,
    body: "My bad!",
  };
  try {
    const awsRequest = await lambdaRuntimeIncomingRequest.json();
    responseBody = await handler(awsRequest);
  } catch (error) {
    logError("error", error);
    throw error;
  }

  const awsResponse = await fetch(
    `http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/${requestId}/response`,
    {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(responseBody),
    },
  );
  await shutdownBackend();
  return awsResponse;
}

export default async function serveLambda<T = APIGatewayEvent>(
  handler: Handler<T>,
) {
  const args = Deno.args;
  if (args[0] === "cache") {
    log("Exiting because all we wanted to do was cache the dependencies");
    return;
  }
  log("info", "Starting Lambda runtime server");
  logInfo(`waiting at ${Date.now()}`);
  while (true) {
    log("debug", "Awaiting request");

    try {
      const incomingRequest = await fetch(
        `http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next`,
        {
          signal: abortController.signal,
        },
      );

      await respond<T>(incomingRequest, handler);
    } catch (_e) {
      break;
    }

    abortController = new AbortController();
  }
}