Deno Sandbox: Secure Runtime for AI-Generated Code

The rise of AI coding assistants and LLM-powered development tools has created a new challenge for DevOps and SRE teams: how do you safely execute code that was generated by an AI without human review? Traditional sandboxing approaches fall short when that code needs API keys and network access to function. Deno Sandbox addresses this gap with lightweight microVMs that protect secrets and control network egress at the infrastructure level.

The Problem with AI-Generated Code

When users generate code with LLMs, that code often needs to:

• Call external APIs (OpenAI, Anthropic, etc.)
• Access credentials and API keys
• Make network requests to various services

Running this code directly on your servers is a security nightmare. It could compromise your system, steal API keys, or exfiltrate data to malicious endpoints. Traditional sandboxing isolates compute but doesn't solve the credential and network problems.

What is Deno Sandbox?

Deno Sandbox provides lightweight Linux microVMs running in the Deno Deploy cloud. These sandboxes boot in under a second and offer defense-in-depth security for running untrusted code. You can create and manage sandboxes programmatically via JavaScript or Python SDKs.

import { Sandbox } from "@deno/sandbox";

await using sandbox = await Sandbox.create();
await sandbox.sh`ls -lh /`;

Secrets That Can't Be Stolen

The killer feature of Deno Sandbox is its approach to secret management. Secrets never actually enter the sandbox environment. Code sees only a placeholder value:

import { Sandbox } from "@deno/sandbox";

await using sandbox = await Sandbox.create({
  secrets: {
    OPENAI_API_KEY: {
      hosts: ["api.openai.com"],
      value: process.env.OPENAI_API_KEY,
    },
  },
});

await sandbox.sh`echo $OPENAI_API_KEY`;
// Prints a placeholder, not the real key

The real API key only materializes when the sandbox makes an outbound request to an approved host. If prompt-injected code tries to send that placeholder to a malicious server, it's completely useless.

Network Egress Control

You can also restrict which hosts the sandbox can communicate with:

await using sandbox = await Sandbox.create({
  allowNet: ["api.openai.com", "*.anthropic.com"],
});

Any request to an unlisted host gets blocked at the VM boundary. This prevents data exfiltration even if the sandboxed code is compromised.

Both features are implemented via an outbound proxy that provides a chokepoint for policy enforcement. For JavaScript and TypeScript workloads, you can combine this with Deno's --allow-net flag for defense in depth.

From Sandbox to Production

When your sandboxed code is ready for production, deployment is a single function call:

const build = await sandbox.deploy("my-app", {
  production: true,
  build: { mode: "none", entrypoint: "server.ts" },
});

const revision = await build.done;
console.log(revision.url);

No rebuilding in a different CI system, no re-authenticating with different tools. Your dev environment becomes a production-ready, auto-scaling serverless deployment.

Persistence Options

While sandboxes are ephemeral by default, Deno Sandbox supports persistent storage when needed:

• Volumes: Read-write storage for caches, databases, and user data
• Snapshots: Read-only images for pre-installed toolchains

Run apt-get install once, snapshot it, and every future sandbox boots with everything pre-installed. Create read-write volumes from snapshots to spin up fresh development environments in seconds.

Technical Specifications

Spec	Value
Regions	Amsterdam, Chicago
vCPUs	2
Memory	768 MB - 4 GB
Boot time	< 1 second
Max lifetime	30 minutes

Use Cases for SRE Teams

Deno Sandbox is particularly useful for:

• AI agents executing code: Let your AI assistants run code safely without risking your infrastructure
• Vibe-coding environments: Provide users with instant, isolated development environments
• Secure plugin systems: Run customer-supplied code without compromising your platform
• Ephemeral CI runners: Spin up isolated build environments on demand
• Code evaluation services: Build REPLs and code playgrounds with proper isolation

Pricing

Deno Sandbox is included in Deno Deploy plans with usage-based pricing:

• $0.05/h CPU time (40h included with Pro)
• $0.016/GB-h memory (1000 GB-h included with Pro)
• $0.20/GiB-month volume storage (5 GiB included with Pro)

Getting Started

Deno Sandbox is available in beta alongside the general availability of Deno Deploy:

• Landing page: deno.com/sandbox
• Documentation: docs.deno.com/sandbox
• JavaScript SDK: jsr.io/@deno/sandbox
• Python SDK: pypi.org/project/deno-sandbox

Conclusion

As AI-generated code becomes more prevalent in development workflows, secure execution environments are no longer optional. Deno Sandbox provides a production-ready solution with secret protection, network egress control, and a seamless path from development to deployment.

For efficient incident management and to prevent on-call burnout, consider using Akmatori. Akmatori automates incident response, reduces downtime, and simplifies troubleshooting.

Additionally, for reliable virtual machines and bare metal servers worldwide, check out Gcore.