Setting Node and PNPM versions in Cloudflare Workers programmatically

You can set them by adding the NODE_VERSION and PNPM_VERSION env vars in the Cloudflare Workers dashboard, which is what I did initially, but I wanted to use version ranges and so preferred to set them in code rather than the dashboard.

I’ve wasted a couple of hours so you don’t have to.

Node

//.nvmrc
// this uses specifically node v24.16.0
24.16.0

// this uses the latest lts version, whether its 22, 24 or 26.
lts/*

// THIS DOES NOT WORK!!
// it works locally, but not inside cloudflare workers
lts/krypton

To specify a node version, you must use a .nvmrc file.

PNPM

// package.json
{
  "packageManager": "pnpm@11.6.0",
  "devEngines": {
    "packageManager": {
      "name": "pnpm",
      "version": "11.6.0",
      "onFail": "download"
    }
  }
}

To specify a pnpm version, you have to add a packageManager field to your package.json. The pnpm site recommends you add devEngines.packageManager for reasons I will not go into. So you end up having to do this.

There are some issues with this.

The packageManager field is enforced by Corepack and as a matter of policy, does not support version ranges. Ref

The packageManager field not supporting ranges is a feature, not a bug.

PNPM however, does support version ranges in devEngines.packageManager, which clashes with Corepack’s policy. So if packageManager is used, devEngines.packageManager must also specify a single version.

There are more, but this is the main issue for me.

wrangler.jsonc

The wrangler docs specify a vars field for environmental variables. It does not work for Node and PNPM.