Minimal repro for Cloudflare Sandbox local startup failure (proxy-everything exits with setsockoptint: protocol not available)

README.md

Cloudflare Sandbox local-dev repro

This is a minimal repro for local Cloudflare Sandbox startup failure.

Environment

• macOS 15.3.0 (Darwin 25.3.0, arm64)
• Bun 1.3.11
• Node v20.20.1
• Wrangler 4.77.0
• Docker 28.5.2
• Docker context: orbstack

Install

bun install

Run

bun run dev

In another terminal:

curl -i http://localhost:8787/run

Expected

The worker should start a sandbox container and return JSON with the output of:

echo hello from sandbox

Actual

The request hangs while the Sandbox DO retries container readiness. Wrangler logs show:

Monitoring container failed with: 404 {"message":"No such container: workerd-cf-sandbox-minimal-Sandbox-..."}

Docker shows the proxy sidecar exits immediately:

docker logs workerd-cf-sandbox-minimal-Sandbox-...-proxy
Fatal error:  setsockoptint: protocol not available

Dockerfile

FROM docker.io/cloudflare/sandbox:0.7.20

WORKDIR /workspace

index.ts

import {
  getSandbox,
  type Sandbox as SandboxType,
  proxyToSandbox,
  Sandbox,
} from "@cloudflare/sandbox";

type Env = {
  Sandbox: DurableObjectNamespace<SandboxType>;
};

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const proxyResponse = await proxyToSandbox(request, env);
    if (proxyResponse) {
      return proxyResponse;
    }

    const url = new URL(request.url);

    if (url.pathname === "/run") {
      const sandbox = getSandbox(env.Sandbox, "minimal-test");

      await sandbox.setEnvVars({
        NODE_ENV: "production",
      });

      const result = await sandbox.exec("echo hello from sandbox");

      return Response.json({
        success: result.success,
        stdout: result.stdout,
        stderr: result.stderr,
        exitCode: result.exitCode,
      });
    }

    return new Response("Try GET /run");
  },
} satisfies ExportedHandler<Env>;

export { Sandbox };

package.json

{
  "name": "cf-sandbox-minimal",
  "private": true,
  "type": "module",
  "scripts": {
    "dev": "wrangler dev --port 8787",
    "cf-typegen": "wrangler types"
  },
  "dependencies": {
    "@cloudflare/sandbox": "0.7.20"
  },
  "devDependencies": {
    "@cloudflare/workers-types": "^4.20260301.0",
    "wrangler": "^4.77.0"
  }
}

wrangler.jsonc

{
  "$schema": "node_modules/wrangler/config-schema.json",
  "name": "cf-sandbox-minimal",
  "main": "src/index.ts",
  "compatibility_date": "2026-03-17",
  "compatibility_flags": [
    "nodejs_compat",
    "nodejs_compat_populate_process_env"
  ],
  "containers": [
    {
      "class_name": "Sandbox",
      "image": "./Dockerfile"
    }
  ],
  "durable_objects": {
    "bindings": [
      {
        "name": "Sandbox",
        "class_name": "Sandbox"
      }
    ]
  },
  "migrations": [
    {
      "tag": "v1",
      "new_sqlite_classes": [
        "Sandbox"
      ]
    }
  ]
}