NodeJS 14.x – Native AWS Lambda Import/Export Support

I am looking to make use of the native import/export that comes with ES6.

I am using Serverless Containers within AWS Lambda.

I have my Dockerfile which looks like this:

FROM public.ecr.aws/lambda/nodejs:14

COPY app ./

RUN npm install

CMD [ "app.handler" ]

I then have an app directory with my application code. The app.js code looks like this:

import { success } from './utils/log';

exports.handler = async () => {
  success('lambda invoked');
  const response = 'Hello World';
  return {
    statusCode: 200,
    body: JSON.stringify(response),
    isBase64Encoded: false,
  };
};

As you can see from this line import { success } from './utils/log'; I am making use of native imports.

In my package.json I specify this:

  "type": "module"

As I need to tell my application this is a module and I would like imports natively. If I don’t specify this, I get:

{
    "errorType": "Runtime.UserCodeSyntaxError",
    "errorMessage": "SyntaxError: Cannot use import statement outside a module",
    "stack": [
        "Runtime.UserCodeSyntaxError: SyntaxError: Cannot use import statement outside a module",
        "    at _loadUserApp (/var/runtime/UserFunction.js:98:13)",
        "    at Object.module.exports.load (/var/runtime/UserFunction.js:140:17)",
        "    at Object.<anonymous> (/var/runtime/index.js:43:30)",
        "    at Module._compile (internal/modules/cjs/loader.js:1063:30)",
        "    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)",
        "    at Module.load (internal/modules/cjs/loader.js:928:32)",
        "    at Function.Module._load (internal/modules/cjs/loader.js:769:14)",
        "    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)",
        "    at internal/main/run_main_module.js:17:47"
    ]
}

So, I specify it, telling Lambda this is a module. However, for the life of me I can’t get it to work, I am seeing this error:

{
    "errorType": "Error",
    "errorMessage": "Must use import to load ES Module: /var/task/app.jsnrequire() of ES modules is not supported.nrequire() of /var/task/app.js from /var/runtime/UserFunction.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.nInstead rename app.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from /var/task/package.json.n",
    "code": "ERR_REQUIRE_ESM",
    "stack": [
        "Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /var/task/app.js",
        "require() of ES modules is not supported.",
        "require() of /var/task/app.js from /var/runtime/UserFunction.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.",
        "Instead rename app.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from /var/task/package.json.",
        "",
        "    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1080:13)",
        "    at Module.load (internal/modules/cjs/loader.js:928:32)",
        "    at Function.Module._load (internal/modules/cjs/loader.js:769:14)",
        "    at Module.require (internal/modules/cjs/loader.js:952:19)",
        "    at require (internal/modules/cjs/helpers.js:88:18)",
        "    at _tryRequire (/var/runtime/UserFunction.js:75:12)",
        "    at _loadUserApp (/var/runtime/UserFunction.js:95:12)",
        "    at Object.module.exports.load (/var/runtime/UserFunction.js:140:17)",
        "    at Object.<anonymous> (/var/runtime/index.js:43:30)",
        "    at Module._compile (internal/modules/cjs/loader.js:1063:30)"
    ]
}

It looks like /var/runtime/UserFunction.js is calling my app handler as a require and a module. However, I have no control over /var/runtime/UserFunction.js (I don’t believe?). In my Dockerfile I have specified Node14. I don’t quite know where I have gone wrong?

What I am looking to do is run the latest and greatest of Node14 (such as imports) without Babel/Transpiler that “bloat” my code. If someone could point me in the right direction of where I have gone wrong, it would be appreciated.

Answer

It appears that since yesterday there finally is native support for the ES6 module syntax in Node 14 lambdas – see https://aws.amazon.com/blogs/compute/using-node-js-es-modules-and-top-level-await-in-aws-lambda