ERR_MODULE_NOT_FOUND in latest 8.4.0 version

[Awlie]

Hello,

the newest version 8.4.0 was recently released.

We are running python lambdas and the warum plugin is the only nodejs lambda.

After upgrading from 8.3.0 without any other changes, the warmup lambda fails with the following error

{
    "errorType": "Error",
    "errorMessage": "Cannot find package '@smithy/node-http-handler' imported from /var/task/.warmup/officeHoursWarmer/index.mjs",
    "code": "ERR_MODULE_NOT_FOUND",
    "stack": [
        "Error [ERR_MODULE_NOT_FOUND]: Cannot find package '@smithy/node-http-handler' imported from /var/task/.warmup/officeHoursWarmer/index.mjs",
        "    at Object.getPackageJSONURL (node:internal/modules/package_json_reader:316:9)",
        "    at packageResolve (node:internal/modules/esm/resolve:774:81)",
        "    at moduleResolve (node:internal/modules/esm/resolve:864:18)",
        "    at moduleResolveWithNodePath (node:internal/modules/esm/resolve:996:14)",
        "    at defaultResolve (node:internal/modules/esm/resolve:1039:79)",
        "    at #cachedDefaultResolve (node:internal/modules/esm/loader:757:20)",
        "    at ModuleLoader.resolve (node:internal/modules/esm/loader:734:38)",
        "    at ModuleLoader.getModuleJobForImport (node:internal/modules/esm/loader:317:38)",
        "    at #link (node:internal/modules/esm/module_job:208:49)"
    ]
}

looking at recent changes and at the lambda, line 5 with the NodeHttpHandler seems the be the issue

/** Generated by Serverless WarmUp Plugin **/

import { LambdaClient, InvokeCommand } from '@aws-sdk/client-lambda';
import { NodeHttpHandler } from '@smithy/node-http-handler';

const uninstrumentedLambdaClient = new LambdaClient({
  apiVersion: '2015-03-31',
  region: 'eu-central-1',
  requestHandler: new NodeHttpHandler({ connectionTimeout: 1000 }),
});

since there is no node_modules with @smithy/node-http-handler

This change was added in this commit: 05d8829

i downgraded to 8.3.0 for now

what would be a fix for that? is there a workaround?

[Awlie]

didn't check the open PRs, might be addressed in #364 , but didn't look at the code

[elise-ng]

we are having a related issue where serverless-webpack auto-adds @smithy/node-http-handler to webpack's build time package.json while copying yarn.lock from project root, so it complains the yarn lock is out of sync when bundling

[onurkose]

If you don't want to upgrade your nodejs version to 24 in lambda, fix your warmup plugin to 8.3.0 like this:
"serverless-plugin-warmup": "8.3.0"
It's hard to understand why it's not a breaking change, and not released under v9.

[caaarlxs]

I hit the same issue when upgrading, after digging into it, the problem seems to come from the generated warmup handler importing @smithy/node-http-handler while the warmup artifact only contains .warmup/**, so the dependency is missing at runtime.

I opened PR #364 which bundles the generated warmup handler with esbuild, so it becomes self-contained and doesn't rely on external node_modules anymore.

If you want, you can try that branch — it should remove the need to manually include @smithy/* in package patterns or downgrading your version