Empty api responses on OpenNext/SST

[MaxiMittel]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/nextjs

SDK Version

7.69.0

Framework Version

NextJS 12.3.0

Link to Sentry event

No response

SDK Setup

No response

Steps to Reproduce

We are moving our existing NestJS from Amplify Hosting to AWS Lambda. We chose to use the cdk and the cdk-nextjs npm package. (GitHub: cdk-nextjs). This is built upon the OpenNext package from SST.

We were able to deploy the app using the stated packages without any trouble, but all of our API routes returned nothing. After some investigation we concluded that it's related to sentry, when we removed the withSentryConfig from our next.config.js the api routes started working again. What's weird is that the same code with sentry works on Amplify but does not with OpenNext.

Expected Result

Api routes should return something.

Actual Result

This is my next.config.js:

const { withSentryConfig } = require("@sentry/nextjs");

/** @type {import('next').NextConfig} */
const nextConfig = {
  reactStrictMode: true,
  swcMinify: true,
  webpack: (config, { isServer }) => {
    if (!isServer) {
      config.resolve.fallback = {
        fs: false,
      };
    }
    return config;
  },
  env: {...},
  sentry: {
    hideSourceMaps: true,
    excludeServerRoutes: ["/api/auth/[...nextauth]"],
  },
  images: {...},
};

const sentryWebpackPluginOptions = {
  silent: true,
};

//console.dir(process.env, { depth: null });

module.exports = withSentryConfig(nextConfig, sentryWebpackPluginOptions);

Even the most basic endpoints fail, the status code gets set correctly but no information is sent.

import type { NextApiRequest, NextApiResponse } from "next";

async function handler(req: NextApiRequest, res: NextApiResponse<any>) {
  res.status(201).json({ message: "success" });
}

export default handler;

There is no error anywhere, not in Sentry not in CloudWatch it's just an empty response. Did anybody encounter something similar and has a solution?

[Lms24]

Hey @MaxiMittel thanks for writing in!

Do you get any debug output if you set debug: true in your sentry.(client|server).config.js? Would be interesting to see what's loggged at startup and when an API request is made.

I'm not familiar with cdk-nextjs. If you could provide a GitHub repo with a minimal reproduction, we can look further into this. Thanks!

[MaxiMittel]

Hey @Lms24,

after some further research I came across this issue in the OpenNext repository. The temporary fix mentioned by him setting autoInstrumentServerFunctions: false did also work for me. He also provides a minimal example.

The debug output shows no errors whatsoever (I removed autoInstrumentServerFunctions again)

  | 2023-09-18T10:30:48.457+02:00 | START RequestId: a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d Version: $LATEST
  | 2023-09-18T10:30:48.505+02:00 | 2023-09-18T08:30:48.505Z a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d INFO Sentry Logger [log]: Initializing SDK...
  | 2023-09-18T10:30:48.506+02:00 | 2023-09-18T08:30:48.506Z a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d INFO Sentry Logger [log]: SDK already initialized
  | 2023-09-18T10:30:48.614+02:00 | 2023-09-18T08:30:48.614Z a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d INFO Sentry Logger [log]: [Tracing] starting http.server transaction - GET /api/courses/count
  | 2023-09-18T10:30:48.916+02:00 | 2023-09-18T08:30:48.916Z a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d INFO Sentry Logger [log]: [Tracing] Finishing http.server transaction: GET /api/courses/count.
  | 2023-09-18T10:30:48.920+02:00 | 2023-09-18T08:30:48.920Z a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d INFO Sentry Logger [log]: Flushing events...
  | 2023-09-18T10:30:48.923+02:00 | END RequestId: a0c6b3f7-9de5-49be-8eb9-bdbdfea14a4d

[lforst]

@MaxiMittel Setting autoInstrumentServerFunctions: false is gonna heavily decrease the value you get out of the SDK unless you manually instrument every single route handler, server component, data fetcher in your app.

We don't officially support cdk-nextjs or OpenNext. I recommend raising an issue in their repository. Maybe they have an idea of what's going on.