Cloudflare Sandbox SDK

Post by alooPotato » Thu, Oct 16, 2025, 11:08 PM UTC

SparkyMcUnicorn wrote: post #30

alooPotato wrote: post #25

There is an open question about how file persistence works. The docs claim they persist the filesystem even when they move the container to an idle state but its unclear exactly what that means - https://github.com/cloudflare/sandbox-sdk/issues/102

To me, the docs answer it pretty clearly. The defined directories persist until you destroy(). The part that's unclear to me is how billing works for a sandbox's disk that's asleep, because container disks are ephemeral and don't survive sleep[2] but the sandbox pricing points you to containers which says "Charges stop after the container instance goes to sleep". https://developers.cloudflare.com/sandbox/concepts/san…

Post by Imustaskforhelp » Thu, Oct 16, 2025, 11:20 PM UTC

eis wrote: post #21

Cloudflare Containers (and therefore Sandbox) pricing is way too expensive. The pricing is a bit cumbersome to understand by being inconsistent with pricing of other Cloudflare products in terms of units and split between memory, cpu and disk instead of combined per instance. The worst is that it is given in these tiny fractions per second. Memory: $0.0000025 per additional GiB-second vCPU: $0.000020 per additional v…

Post by jumploops » Thu, Oct 16, 2025, 11:48 PM UTC

_pdp_ wrote: post #7

Looks nice. We rolled out our own that does pretty much the same thing but perhaps more because our solution can also mount persistent storage that can be carried between multiple runners. It does take 1-5 seconds to boot the environment (firecracker vms). If this sandbox is faster I will instruct the team to consider for fast starup. This is also very similar to Vercel's sandbox thing. The same technology? What I do…

Post by rvcdbn » Fri, Oct 17, 2025, 12:15 AM UTC

paxys wrote: post #15

simonw wrote: post #14

Looks like there's one feature missing from this that I care about: I'd like more finely grained control over what outbound internet connections code running on the box can make. As far as I can tell it's all or nothing right now: this.ctx.container.start({ enableInternet: false, }); I want to run untrusted code (from users or LLMs) in these containers, and I'd like to avoid someone malicious using my container to la…

This simple feature bumps up the complexity of such a firewall by several orders of magnitude, which is why no similar runtime (like Deno) offers it. Networking as a whole can easily be controlled by the OS or any intermediate layer. For controlling access to specific sites you need to either filter it at the DNS level, which can be trivially bypassed, or bake something into the application binary itself. But if you…

Post by chatmasta » Fri, Oct 17, 2025, 12:22 AM UTC

paxys wrote: post #15

simonw wrote: post #14

Looks like there's one feature missing from this that I care about: I'd like more finely grained control over what outbound internet connections code running on the box can make. As far as I can tell it's all or nothing right now: this.ctx.container.start({ enableInternet: false, }); I want to run untrusted code (from users or LLMs) in these containers, and I'd like to avoid someone malicious using my container to la…

This simple feature bumps up the complexity of such a firewall by several orders of magnitude, which is why no similar runtime (like Deno) offers it. Networking as a whole can easily be controlled by the OS or any intermediate layer. For controlling access to specific sites you need to either filter it at the DNS level, which can be trivially bypassed, or bake something into the application binary itself. But if you…