bun.sh/examples/lambda.ts

const { AWS_LAMBDA_RUNTIME_API, LAMBDA_TASK_ROOT, _HANDLER } = process.env;

if (!AWS_LAMBDA_RUNTIME_API || AWS_LAMBDA_RUNTIME_API === "") {
  throw new Error("AWS_LAMBDA_RUNTIME_API is not set");
}

const nextURL = `http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next`;
const sourceDir = LAMBDA_TASK_ROOT;
if (!sourceDir) {
  throw new Error("handler is not set");
}

// don't care if this fails
if (process.cwd() !== sourceDir) {
  try {
    process.chdir(sourceDir);
  } catch (e) {}
}

var handlerDot = _HANDLER.lastIndexOf(".");
var sourcefile = handlerDot > 0 ? _HANDLER.substring(0, handlerDot) : _HANDLER;
if (sourcefile.length === 0) {
  throw new Error("handler is not set");
}
if (!sourcefile.startsWith("/")) {
  sourcefile = `./${sourcefile}`;
}
function noop() {}
const method = (handlerDot > 0 ? _HANDLER.substring(handlerDot) : "") || "GET";

if (typeof process.env.VERBOSE !== "undefined") {
  console.time(`Loaded ${sourcefile}`);
}
var Handler;

try {
  Handler = await import(sourcefile);
} catch (e) {
  console.error("Error loading sourcefile:", e);
  try {
    await fetch(
      new URL(`http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/init/error`)
        .href,
      {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          errorMessage: e.message,
          errorType: e.name,
          stackTrace: e?.stack?.split("\n") ?? [],
        }),
      }
    );
  } catch (e2) {
    console.error("Error sending error to runtime:", e2);
  }
  process.exit(1);
}

if (typeof process.env.VERBOSE !== "undefined") {
  console.timeEnd(`Loaded ${sourcefile}`);
}

const handlerFunction = Handler.default?.fetch;
if (typeof handlerFunction !== "function") {
  const e = new Error(`${sourcefile} must export default a function called fetch

Here is an example:

export default {
    fetch(req) {
        return new Response("Hello World");
    }
}
`);

  console.error(e);

  try {
    await fetch(
      new URL(`http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/init/error`)
        .href,
      {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          errorMessage: e.message,
          errorType: e.name,
          stackTrace: e?.stack?.split("\n") ?? [],
        }),
      }
    );
  } catch (e2) {
    console.error("Error sending error to runtime:", e2);
  }

  process.exit(1);
}

var baseURLString = AWS_LAMBDA_RUNTIME_API;
if ("baseURI" in Handler.default) {
  baseURLString = Handler.default.baseURI?.toString();
}

var baseURL;
try {
  baseURL = new URL(baseURLString);
} catch (e) {
  console.error("Error parsing baseURI:", e);
  try {
    await fetch(
      new URL(`http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/init/error`)
        .href,
      {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          errorMessage: e.message,
          errorType: e.name,
          stackTrace: e?.stack?.split("\n") || [],
        }),
      }
    );
  } catch (e2) {
    console.error("Error sending error to runtime:", e2);
  }

  process.exit(1);
}

async function runHandler(response: Response) {
  const traceID = response.headers.get("Lambda-Runtime-Trace-Id");
  const requestID = response.headers.get("Lambda-Runtime-Aws-Request-Id");
  var request = new Request(baseURL.href, {
    method,
    headers: response.headers,
    body:
      parseInt(response.headers.get("Content-Length") || "0", 10) > 0
        ? await response.blob()
        : undefined,
  });
  // we are done with the Response object here
  // allow it to be GC'd
  response = undefined;

  var result: Response;
  try {
    if (typeof process.env.VERBOSE !== "undefined") {
      console.time(`[${traceID}] Run ${request.url}`);
    }
    result = handlerFunction(request, {});
    if (result && result.then) {
      await result;
    }
  } catch (e1) {
    if (typeof process.env.VERBOSE !== "undefined") {
      console.error(`[${traceID}] Error running handler:`, e1);
    }
    fetch(
      `http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/${requestID}/error`,
      {
        method: "POST",

        body: JSON.stringify({
          errorMessage: e1.message,
          errorType: e1.name,
          stackTrace: e1?.stack?.split("\n") ?? [],
        }),
      }
    ).finally(noop);
    return;
  } finally {
    if (typeof process.env.VERBOSE !== "undefined") {
      console.timeEnd(`[${traceID}] Run ${request.url}`);
    }
  }

  if (!result || !("headers" in result)) {
    await fetch(
      `http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/${requestID}/error`,
      {
        method: "POST",
        body: JSON.stringify({
          errorMessage: "Expected Response object",
          errorType: "ExpectedResponseObject",
          stackTrace: [],
        }),
      }
    );
    return;
  }

  await fetch(
    `http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/${requestID}/response`,
    {
      method: "POST",
      headers: result.headers,
      body: await result.blob(),
    }
  );
  result = undefined;
}

while (true) {
  fetch(nextURL).then(runHandler, console.error);
}

export {};