What causes "spawn is not supported in Cloudflare Workers" in DIYgod/RSSHub?

Prevent the spawn code path under Workers (runtime gate or alternative API).

spawn is not supported in Cloudflare Workers

Error message

spawn is not supported in Cloudflare Workers

What it means

Inline child_process.spawn() in lib/shims/node-module.ts throws — Workers cannot spawn subprocesses. This is the inlined duplicate of the standalone child-process shim, kept so createRequire's child_process builtin is shape-complete except for the throwing members.

Source

Thrown at lib/shims/node-module.ts:87

    },
    runInThisContext: () => {
        throw new Error('vm.runInThisContext is not supported in Workers');
    },
    Script: ScriptShim,
    isContext: () => false,
    compileFunction: () => {
        throw new Error('vm.compileFunction is not supported in Workers');
    },
};

// Child process shim (inline to avoid import cycle)
const child_process = {
    execSync: (_command: string): Buffer => Buffer.from(''),
    exec: () => {
        throw new Error('exec is not supported in Cloudflare Workers');
    },
    spawn: () => {
        throw new Error('spawn is not supported in Cloudflare Workers');
    },
    fork: () => {
        throw new Error('fork is not supported in Cloudflare Workers');
    },
    execFile: () => {
        throw new Error('execFile is not supported in Cloudflare Workers');
    },
    execFileSync: () => {
        throw new Error('execFileSync is not supported in Cloudflare Workers');
    },
    spawnSync: () => {
        throw new Error('spawnSync is not supported in Cloudflare Workers');
    },
};

// Create a CJS-compatible events module
// In CJS, require('events') returns EventEmitter class directly (the default export)
// but also has named exports attached to it

View on GitHub (pinned to bed535e087)

Solutions

Prevent the spawn code path under Workers (runtime gate or alternative API).
Use fetch/stream APIs instead of subprocess streaming.
Deploy the route on Node.

Example fix

// before
require('child_process').spawn('ffmpeg', args);
// after — stream via fetch under Workers
const res = await fetch(mediaUrl);

Defensive patterns

Strategy: validation

Validate before calling

const isNode = typeof process !== 'undefined' && !!process.versions?.node;
if (!isNode) {
  // Workers: replace require('child_process').spawn with fetch/stream
}

Type guard

function isWorkersShimError(e: unknown): e is Error {
  return e instanceof Error && /not supported in Cloudflare Workers/.test(e.message);
}

Try / catch

try {
  if (isNode) require('child_process').spawn(bin, args);
  else return streamViaFetch(url);
} catch (e) {
  if (isWorkersShimError(e)) return streamViaFetch(url);
  throw e;
}

Prevention

Block the spawn path in CJS deps under Workers.
Use fetch/ReadableStream instead of subprocess streaming.
Keep subprocess routes on Node.

When it happens

Trigger: A CJS dependency reached via createRequire that calls child_process.spawn() at runtime under Workers.

Common situations: Streaming subprocess wrappers; media tool launchers loaded through a CJS require chain.

Related errors

AI-assisted analysis of DIYgod/RSSHub@bed535e087 (2026-08-12). Data as JSON: /api/errors/0bf90256daf18219. Report an issue: GitHub.