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Deno Sandbox

Note that you don't need to use Deno or JavaScript at all to use this product. Here's their Python client SDK: https://pypi.org/project/deno-sandbox/

  from deno_sandbox import DenoDeploy
  
  sdk = DenoDeploy()
  
  with sdk.sandbox.create() as sb:
      # Run a shell command
      process = sb.spawn("echo", args=["Hello from the sandbox!"])
      process.wait()
  
      # Write and read files
      sb.fs.write_text_file("/tmp/example.txt", "Hello, World!")
      content = sb.fs.read_text_file("/tmp/example.txt")
      print(content)
Looks like the API protocol itself uses websockets: https://tools.simonwillison.net/zip-wheel-explorer?package=d...
3 hours agosimonw

> In Deno Sandbox, secrets never enter the environment. Code sees only a placeholder

> The real key materializes only when the sandbox makes an outbound request to an approved host. If prompt-injected code tries to exfiltrate that placeholder to evil.com? Useless.

That seems clever.

3 hours agoemschwartz

Reminds me a little of Fly's Tokenizer - https://github.com/superfly/tokenizer

It's a little HTTP proxy that your application can route requests through, and the proxy is what handles adding the API keys or whatnot to the request to the service, rather than your application, something like this for example:

Application -> tokenizer -> Stripe

The secrets for the third party service should in theory then be safe should there be some leak or compromise of the application since it doesn't know the actual secrets itself.

Cool idea!

3 hours agomotrm

It's exactly the tokenizer, but we shoplifted the idea too; it belongs to the world!

(The credential thing I'm actually proud of is non-exfiltratable machine-bound Macaroons).

Remember that the security promises of this scheme depend on tight control over not only what hosts you'll send requests to, but what parts of the requests themselves.

2 hours agotptacek

Yeah, this is a really neat idea: https://deno.com/blog/introducing-deno-sandbox#secrets-that-...

  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`;
  // DENO_SECRET_PLACEHOLDER_b14043a2f578cba75ebe04791e8e2c7d4002fd0c1f825e19...
It doesn't prevent bad code from USING those secrets to do nasty things, but it does at least make it impossible for them to steal the secret permanently.

Kind of like how XSS attacks can't read httpOnly cookies but they can generally still cause fetch() requests that can take actions using those cookies.

3 hours agosimonw

> It doesn't prevent bad code from USING those secrets to do nasty things, but it does at least make it impossible for them to steal the secret permanently.

Agreed, and this points to two deeper issues: 1. Fine-grained data access (e.g., sandboxed code can only issue SQL queries scoped to particular tenants) 2. Policy enforced on data (e.g., sandboxed code shouldn't be able to send PII even to APIs it has access to)

Object-capabilities can help directly with both #1 and #2.

I've been working on this problem -- happy to discuss if anyone is interested in the approach.

an hour agoryanrasti

We had this same challenge in our own app builder, we ended up creating an internal LLM proxy with per-sandbox virtual keys (which the proxy maps to the real key + calculates per-sandbox usage), so even if the sandbox leaks its key it doesn't impact anything else.

an hour agoartahian

I was just about to say the same thing. Cool technique.

3 hours agoperfmode

It must be performing a man-in-the-middle for HTTPS requests. That makes it more difficult to do things like certificate pinning.

3 hours agoTepix
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2 hours ago

This is an old trick that people do with Envoy all the time.

2 hours agoCuriouslyC

I like this, but the project mentioned in the launch post

> via an outbound proxy similar to coder/httpjail

looks like AI slop ware :( I hope they didn't actually run it.

2 hours agorfoo

We run or own infrastructure for this (and everything else). The link was just an illustrative example

37 minutes agolucacasonato

Love their network filtering, however it definitely lacks some capabilities (like the ability to do direct TCP connections to Postgres, or direct IP connections.

Those limitations from other tools was exactly why I made https://github.com/danthegoodman1/netfence for our agents

7 minutes agodangoodmanUT

"Over the past year, we’ve seen a shift in what Deno Deploy customers are building: platforms where users generate code with LLMs, and that code runs immediately without review. That code frequently calls LLMs itself, which means it needs API keys and network access.

This isn’t the traditional “run untrusted plugins” problem. It’s deeper: LLM-generated code, calling external APIs with real credentials, without human review. Sandboxing the compute isn’t enough. You need to control network egress and protect secrets from exfiltration.

Deno Sandbox provides both. And when the code is ready, you can deploy it directly to Deno Deploy without rebuilding."

3 hours agojohnspurlock

Like the emdash, whenever I read: "this isn't x it's y" my dumb monkey brain goes "THATS AI" regardless if it's true or not.

3 hours agotwosdai

I can confirm Ryan is a real human :)

3 hours agolucacasonato

Is there a chance you could ask Ryan if he had an LLM write/rewrite large parts of this blog post? I don't mind at all if he did or didn't in itself, it's a good and informative post, but I strongly assumed the same while reading the article and if it's truly not LLM writing then it would serve as a super useful indicator about how often I'm wrongly making that assumption.

3 hours agozamadatix

There are multiple signs of LLM-speak:

> Over the past year, we’ve seen a shift in what Deno Deploy customers are building: platforms where users generate code with LLMs and that code runs immediately without review

This isn't a canonical use of a colon (and the dependent clause isn't even grammatical)!

> This isn’t the traditional “run untrusted plugins” problem. It’s deeper: LLM-generated code, calling external APIs with real credentials, without human review.

Another colon-offset dependent paired with the classic, "This isn't X. It's Y," that we've all grown to recognize.

> Sandboxing the compute isn’t enough. You need to control network egress and protect secrets from exfiltration.

More of the latter—this sort of thing was quite rare outside of a specific rhetorical goal of getting your reader excited about what's to come. LLMs (mis)use it everywhere.

> Deno Sandbox provides both. And when the code is ready, you can deploy it directly to Deno Deploy without rebuilding.

Good writers vary sentence length, but it's also a rhetorical strategy that LLMs use indiscriminately with no dramatic goal or tension to relieve.

'And' at the beginning of sentences is another LLM-tell.

an hour agobonsai_spool

Can it be that after reading so many LLM texts we will just subconciously follow the style, because that's what we are used to? No idea how this works for native English speakers, but I know that I lack my own writing style and it is just a pseudo-llm mix of Reddit/irc/technical documentation, as those were the places where I learned written English

24 minutes agor00f

Yes, I think you're right—I have a hard time imagining how we avoid such an outcome. If it matters to you, my suggestion is to read as widely as you're able to. That way you can at least recognize which constructions are more/less associated with an LLM.

When I was first working toward this, I found the LA Review of Books and the London Review of Books to be helpful examples of longform, erudite writing. (edit - also recommend the old standards of The New Yorker and The Atlantic; I just wanted to highlight options with free articles).

I also recommend reading George Orwell's essay Politics and the English Language.

15 minutes agobonsai_spool

> It’s deeper: LLM-generated code, calling external APIs with real credentials, without human review.

This also follows the rule of 3s, which LLMs love, there ya go.

28 minutes agojonny_eh

Yeah, I feel like this is really the smoking gun. Because it's not actually deeper? An LLM running untrusted code is not some additional level of security violation above a plugin running untrusted code. I feel like the most annoying part of "It's not X, it's Y" is that agents often say "It's not X, it's (slightly rephrased X)", lol, but it takes like 30 seconds to work that out.

4 minutes agojohnfn

It's unfortunate that, given the entire corpus of human writing, LLMs have seemingly been fine-tuned to reproduce terrible ad copy from old editions of National Geographic.

(Yes, I split the infinitive there, but I hate that rule.)

18 minutes agotadfisher

As someone that has a habit of maybe overusing em dashes to my detriment, often times, and just something that I try to be mindful of in general. This whole thing of assuming that it's AI generated now is a huge blow. It feels like a personal attack.

2 hours agojavier123454321

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2 hours agocalebhwin

>Deno Sandbox gives you lightweight Linux microVMs (running in the Deno Deploy cloud)

The real question is can the microVMs run in just plain old linux, self-hosted.

an hour agozenmac

Everyone wants to lock you in.

Unfortunately there's no other way to make money. If you're 100% liberally licensed, you just get copied. AWS/GCP clone your product, offer the same offering, and they take all the money.

It sucks that there isn't a middle ground. I don't want to have to build castles in another person's sandbox. I'd trust it if they gave me the keys to do the same. I know I don't have time to do that, but I want the peace of mind.

an hour agoechelon

> allowNet: ["api.openai.com", "*.anthropic.com"],

How to know what domains to allow? The agent behavior is not predefined.

2 hours agoATechGuy

The idea is to gate automatic secret replacement to specific hosts that would use them legitimately to avoid exfiltration.

2 hours agoCuriouslyC

Well, this is the hard part, but the idea is that if you're working with both untrusted inputs and private data/resources, then your agent is susceptible to the "lethal trifecta"[0], and you should be extremely limiting in its ability to have external network access. I would suggest starting with nothing beyond the single AI provider you're using, and only add additional domains if you are certain you trust them and can't do without them.

[0] https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/

2 hours agofalcor84

> evil.com

That website does exist. It may hurt your eyes.

16 minutes agolatexr

What happens if we use Claude Pro or Max plans on them ? It’ll always be a different IP connecting and we might get banned from Anthropic as they think we’re different users

Why limit the lifetime on 30 mins ?

3 hours agottoinou

We'll increase the lifetime in the next weeks - just some tech internally that needs to be adjusted first.

3 hours agolucacasonato

For what it's worth, I do this from about 50 different IPs and have had no issues. I think their heuristics are more about confirming "a human is driving this" and rejecting "this is something abusing tokens for API access".

2 hours agomrkurt

All the time with the same computer ? Maybe it is looking at others metadata, for example local MAC addresses

an hour agottoinou

All the time with a bunch of different sandboxes.

an hour agomrkurt

The free plan makes me want to use it like Glitch. But every free service like this ever has been burned...

an hour agokoolala

See also Sprites (https://news.ycombinator.com/item?id=46557825) which I've been using and really enjoying. There are some key architecture differences between the two, but very similar surface area. It'll be interesting to see if ephemeral + snapshots can be as convenient as stateful with cloning/forking (which hasn't actually dropped yet, although the fly team say it's coming).

Will give these a try. These are exciting times, it's never been a better time to build side projects :)

3 hours agonihakue

If you can create a deno sandbox from a deno sandbox, you could create an almost unkillable service that jumps from one sandbox to the next. Very handy for malicious purposes. ;-)

Just an idea…

3 hours agoTepix

This is, in fact, the biggest problem to solve with any kind of compute platform. And when you suddenly launch things really, really fast, it gets harder.

2 hours agomrkurt

Isn’t that basically how zip-bombs work?

2 hours agorunarberg

Not really, no

29 minutes agokibibu

Can this be used on iOS somehow? I am building a Swift app where this would be very useful but last time I checked I don't think it was possible.

an hour agoMillionOClock

It’s a cloud service - so you can call out to it from anywhere you want. Just don’t ship your credentials in the app itself, and instead authenticate via a server you control.

33 minutes agolucacasonato

Where's the real value for devs in something like this? Hasn't everyone already built this for themselves in the past 2 years? I'm not trying to sound cheeky or poo poo the product, just surprised if this is a thing. I can never read what's useful by gut anymore, I guess.

2 hours agomrpandas

> Hasn't everyone already built this for themselves in the past 2 years?

Even if this was true, "everyone building X independently" is evidence that one company should definitely build X and sell it to everyone

2 hours agoslibhb

Sandboxes with the right persistence and http routing make excellent dev servers. I have about a million dev servers I just use from whatever computer / phone I happen to be using.

It's really useful to just turn a computer on, use a disk, and then plop its url in the browser.

I currently do one computer per project. I don't even put them in git anymore. I have an MDM server running to manage my kids' phones, a "help me reply to all the people" computer that reads everything I'm supposed to read, a dumb game I play with my son, a family todo list no one uses but me, etc, etc.

Immediate computers have made side projects a lot more fun again. And the nice thing is, they cost nothing when I forget about them.

2 hours agomrkurt

I'd love to know more about that "help me reply to all the people" one! I definitely need that.

an hour agosimonw

You will be astonished to know it'a a whole lot of sqlite.

Everything I want to pay attention to gets a token, the server goes and looks for stuff in the api, and seeds local sqlites. If possible, it listens for webhooks to stay fresh.

Mostly the interface is Claude code. I have a web view that gives me some idea of volume, and then I just chat at Claude code to have it see what's going on. It does this by querying and cross referencing sqlite dbs.

I will have claude code send/post a response for me, but I still write them like a meatsack.

It's effectively: long lived HTTP server, sqlite, and then Claude skills for scripts that help it consistently do things based on my awful typing.

an hour agomrkurt

> Hasn't everyone already built this for themselves in the past 2 years?

The short answer is no. And more so, I think that "Everyone I know in my milieu already built this for themselves, but the wider industry isn't talking about it" is actually an excellent idea generator for a new product.

2 hours agofalcor84

In the last one year, we have seen several sandboxing wrappers around containers/VMs and they all target one use case AI agent code execution. Why? perhaps because devs are good at building (wrappers around VMs) and chase the AI hype. But how are these different and what value do they offer over VMs? Sounds like a tarpit idea, tbh.

Here's my list of code execution sandboxing agents launched in the last year alone: E2B, AIO Sandbox, Sandboxer, AgentSphere, Yolobox, Exe.dev, yolo-cage, SkillFS, ERA Jazzberry Computer, Vibekit, Daytona, Modal, Cognitora, YepCode, Run Compute, CLI Fence, Landrun, Sprites, pctx-sandbox, pctx Sandbox, Agent SDK, Lima-devbox, OpenServ, Browser Agent Playground, Flintlock Agent, Quickstart, Bouvet Sandbox, Arrakis, Cellmate (ceLLMate), AgentFence, Tasker, DenoSandbox, Capsule (WASM-based), Volant, Nono

2 hours agoATechGuy

why? because there’s a huge market demand for Sandboxes. no one would be building this if no one would be buying.

disclaimer: i work at E2B

23 minutes agoushakov

I'm not saying sandboxes are not needed, I'm saying VMs/containers already provide the core tech and it's easy to DIY a sandbox. Would love to understand what value E2B offers over VMs?

13 minutes agoATechGuy

we offer secure cloud VMs that scale up to 100k concurrent instances or more.

the value we sell with our cloud is scale, while our Sandboxes are a commodity that we have proudly open-sourced

4 minutes agoushakov

Has everyone really built their own microVMs? I don’t think so.

2 hours agodrewbitt

Saw quite bit on HN.

A quick search this popped up:

https://news.ycombinator.com/item?id=45486006

If we can spin up microVM so quickly, why bother with Docker or other containers at all?

2 hours agozenmac

10 seconds is actually not that impressive. we spin up Sandboxes around 50-200ms at E2B

22 minutes agoushakov

I think a 413 commit repo took a bit of time.

an hour agodrewbitt

That's just over one day worth of commits in a few friends' activity at this point. Thanks to Anthropic.

an hour agomrpandas

Can it be used to sandbox an AI agent, like replacing eg Cursor or Openclaw sandboxing system?

28 minutes agoeric-burel

50/200 Gb free plus $0.5 / Gb out egress data seems expensive when scaling out.

2 hours agosnehesht

Looks promising. Any plans for a version that runs locally/self-host able?

Looks like the main innovation here is linking outbound traffic to a host with dynamic variables - could that be added to deno itself?

3 hours agoe12e

As a bit of an aside, I've gotten back into deno after seeing bun get bought out by an AI company.

I really like it. Startup times are now better than node (if not as good as bun). And being able to put your whole "project" in a single file that grabs dependencies from URLs reduces friction a surprising amount compared to having to have a whole directory with package.json, package-lock.json, etc.

It's basically my "need to whip up a small thing" environment of choice now.

an hour agoLAC-Tech

Now I see why he was on twitter saying that the era of coding is over and hyping up LLMs, to sell more shovels...

27 minutes agobopbopbop7

Firecrackervm with proxy?

3 hours agoianberdin

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