We’ve been using growthbook for a few minutes with the client side SDK, but we’re looking to swap over to lambda edge. I’ve been trying to get it working but not having much luck. I’ve confirmed a basic lambda function is configured w/ our cloudfront, but once I add the growthbook specific handler, I run into errors. When I deploy the lambda version that uses growthbook, I’m seeing logs with this error:

2025-11-18T15:22:00.113Z	a762f8a1-1df6-4c0b-98aa-686ec37e6ff8	ERROR	Unhandled Promise Rejection 	
{
    "errorType": "Runtime.UnhandledPromiseRejection",
    "errorMessage": "TypeError: Invalid URL",
    "reason": {
        "errorType": "TypeError",
        "errorMessage": "Invalid URL",
        "code": "ERR_INVALID_URL",
        "input": "undefined",
        "stack": [
            "TypeError: Invalid URL",
            "    at new URL (node:internal/url:825:25)",
            "    at Ms (/var/task/index.js:31:69858)",
            "    at Object.w3 [as proxyRequest] (/var/task/index.js:31:75389)",
            "    at /var/task/index.js:31:65455",
            "    at Generator.next (<anonymous>)",
            "    at s (/var/task/index.js:31:64093)"
        ]
    },
    "promise": {},
    "stack": [
        "Runtime.UnhandledPromiseRejection: TypeError: Invalid URL",
        "    at process.<anonymous> (file:///var/runtime/index.mjs:1448:17)",
        "    at process.emit (node:events:519:28)",
        "    at emitUnhandledRejection (node:internal/process/promises:252:13)",
        "    at throwUnhandledRejectionsMode (node:internal/process/promises:388:19)",
        "    at processPromiseRejections (node:internal/process/promises:475:17)",
        "    at process.processTicksAndRejections (node:internal/process/task_queues:106:32)"
    ]
}

Nothing is growthbook specific in those logs, but I’m guessing it’s coming from something growthbook is doing. A couple of questions: 1. PROXY_TARGET — I’m pointing this to our S3 bucket that serves the website, which is

http

, not

https

— is that okay? If I use https, that’d point back to a cloudfront distro URL and I think it’d go into some kind of infinite redirect loop 2. Is there a way to test this w/o having to redeploy my cloudfront distro and wait for the website to break

Hey Nate! Did you make any progress here?

I talked to someone at growthbook on the web chat and I don’t think the edge SDK will work for us, so went back to the client side sdk

Gotcha! What was the reason?

It’s too slow and the memory limitations on aws edge functions makes it even worse.

oh, shoot.

I guess we’d have to do some caching w/ a key/value store