instrumentation.ts runtime showing as "edge" even when default runtime is supposed to be "nodejs" in local

[juskek]

Link to the code that reproduces this issue

To Reproduce

1. Create an instrumentation.ts file
2. Above register(), add console.log("instrumentation runtime", process.env.NEXT_RUNTIME);

Current vs. Expected behavior

Current behaviour:
console shows: instrumentation runtime edge

Expected behaviour:
console shows: instrumentation runtime nodejs

I would assume that the default runtime (nodejs) would be used if not specified, as shown in the docs

I had to add export const runtime ='nodejs' to force the instrumentation.ts file to run in the nodejs environment (Edit: this does not work, see below for more context)

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 23.1.0: Mon Oct  9 21:27:27 PDT 2023; root:xnu-10002.41.9~6/RELEASE_X86_64
Binaries:
  Node: 18.19.0
  npm: 10.2.3
  Yarn: 1.22.18
  pnpm: 8.11.0
Relevant Packages:
  next: 14.0.4
  eslint-config-next: 14.0.4
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.2.2
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Middleware / Edge (API routes, runtime)

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

I just realised what the issue is:

• instrumentation.ts runs in the nodejs env when the server is first started, e.g. npm run dev
• When you make a change to the instrumentation.ts file, the server runs instrumentation.ts again, but in the edge env

Is this expected behaviour?

[icyJoseph]

Hi,

According to the docs, https://nextjs.org/docs/app/building-your-application/optimizing/instrumentation#importing-runtime-specific-code:

Next.js calls register in all environments, so it's important to conditionally import any code that doesn't support specific runtimes (e.g. Edge or Node.js). You can use the NEXT_RUNTIME environment variable to get the current environment:

So, it kind of makes sense that you'd see both edge and nodejs while developing. Since this is in experimental mode, I'd expect some quirks though. Probably good to wait a bit before depending on this on production.

[harry-gocity]

So, it kind of makes sense that you'd see both edge and nodejs while developing

We also see this behaviour in the prod build, where instrumentation.ts is called multiple times with the NEXT_RUNTIME env var changing. It looks like this should change in Next 15 - #51450 (comment)

[rubenmamo]

I'm having this issue with the instrumentation not working correctly because I need to have it running in the nodejs runtime

my instrumentation.ts is like so:

import type { SpanExporter } from '@opentelemetry/sdk-trace-base'
import { W3CTraceContextPropagator } from '@opentelemetry/core'
import { registerOTel } from '@vercel/otel'

export async function register() {
  let traceExporter: SpanExporter | undefined
  const appInsightsConnectionString =
    process.env.APPLICATIONINSIGHTS_CONNECTIONSTRING

  if (process.env.NEXT_RUNTIME === 'nodejs' && appInsightsConnectionString) {
    console.log('Open Telemetry setup')
    const { AzureMonitorTraceExporter } = await import(
      '@azure/monitor-opentelemetry-exporter'
    )
    traceExporter = new AzureMonitorTraceExporter({
      connectionString: appInsightsConnectionString,
    })
  } else {
    console.log('no open telemetry')
  }

  registerOTel({
    serviceName: 'Website',
    traceExporter,
    propagators: [new W3CTraceContextPropagator()],
  })
}

and I see these logs in local dev:

17:44:29 - Starting compilation in watch mode...
apps/website dev:   ▲ Next.js 14.2.7
apps/website dev:   - Local:        http://localhost:3000
apps/website dev:   - Environments: .env.local
apps/website dev:   - Experiments (use with caution):
apps/website dev:     · instrumentationHook
apps/website dev:  ✓ Starting...
common/api-client dev: 17:44:30 - Found 0 errors. Watching for file changes.
apps/website dev:  ○ Compiling /instrumentation ...
apps/website dev:  ✓ Compiled /instrumentation in 1187ms (503 modules)
apps/website dev: Open Telemetry setup
apps/website dev:  ✓ Ready in 2.7s

but this when deployed as a standalone container:

2024-08-29T15:32:24.232882798Z   ▲ Next.js 14.2.7
2024-08-29T15:32:24.233013451Z   - Local:        http://localhost:3000
2024-08-29T15:32:24.233022028Z   - Network:      http://0.0.0.0:3000
2024-08-29T15:32:24.233143086Z 
2024-08-29T15:32:24.233165311Z  ✓ Starting...
2024-08-29T15:32:24.733969650Z Open Telemetry setup
2024-08-29T15:32:24.843646521Z  ✓ Ready in 616ms
2024-08-29T15:32:27.331335486Z no open telemetry

[wujekbogdan]

There's something really odd going on here:

Doesn't work:

export const register = async () => {
  const isServer = process.env.NEXT_RUNTIME === "nodejs";
  
  if (isServer) {
    await import("./utils/node-instrumentation");
  }
};

Works fine:

export const register = async () => {
  if (process.env.NEXT_RUNTIME === "nodejs";) {
    await import("./utils/node-instrumentation");
  }
};

What's even funnier is that the first example works fine with next@13.3.4, but it doesn't work with next@13.5.6 or newer. I didn't find the exact version where it "breaks."

I suppose it has something to do with TypeScript compilation or bundling.

[volfadar]

still have this issue in "next": "^15.2.0-canary.66"

[nc1z]

Bump. Same issue as OP.

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