AWS VPC Lambda Connectivity Test

index.mjs

import dns from "node:dns/promises";
import https from "node:https";
import url from "node:url";

const SERVICES = [
  "dynamodb",
  "execute-api",
  "glue",
  "lambda",
  "s3",
  "sns",
  "states",
  "sync-states",
];
const TEST_HOSTS = [
  ...SERVICES.map(
    (service) => `${service}.${process.env.AWS_REGION}.amazonaws.com`
  ),
  `google.com`,
];

const lookup = async (name) => {
  try {
    const result = await dns.lookup(name);
    return { message: `DNS : ${name} → ${result.address}` };
  } catch (error) {
    return { error, message: `DNS : ${name} → <error>` };
  }
};

const get = async (address) => {
  const result = await new Promise((resolve) => {
    const errorResolver = (error) => {
      resolve({ error, statusCode: "<error>" });
    };

    try {
      const request = https.get(address, { timeout: 5000 }, (response) => {
        response
          .on("data", Function.prototype)
          .on("end", () => resolve({ statusCode: response.statusCode }))
          .on("error", errorResolver);
      });
      request.on("error", errorResolver).on("timeout", () => {
        request.off("error", errorResolver);
        request.on("error", Function.prototype);
        request.destroy();
        resolve({ statusCode: "<timeout>" });
      });
    } catch (error) {
      errorResolver(error);
    }
  });

  return {
    error: result.error,
    message: `HTTP: ${address} → ${result.statusCode}`,
  };
};

export const handler = async (_event) => {
  const resultHandler = (result) =>
    result.error
      ? console.log(result.message) ||
        console.error(`└-X-> ${result.error.name}: ${result.error.message}`)
      : console.log(result.message);

  for (const host of TEST_HOSTS) {
    await lookup(host).then(resultHandler);
  }

  for (const host of TEST_HOSTS) {
    await get(`https://${host}/`).then(resultHandler);
  }
};

// Auto-invoke outside of Lambda context.
if (import.meta.url.startsWith("file:")) {
  const modulePath = url.fileURLToPath(import.meta.url);
  if (process.argv[1] === modulePath) {
    handler();
  }
}