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AWS Finally Built Its Own AWS Emulator

267 points super_linear 1 hour ago 70 comments

super_linear 1 hour ago | parent

Related to this post: https://www.aboutamazon.com/news/aws/how-autonomous-ai-agent...

CharlieDigital 1 hour ago | parent

Skeptical of using because it's not clear whether this was just an exercise or a real product they are going to ship and maintain.

Floci[0] has been great for me. Use the Testcontainers[1], too.

Bonus: works for GCP and Azure, too (so far have only used in limited capacity, though).

[0] https://floci.io/

[1] https://testcontainers.com/modules/floci/

ke4qqq 1 hour ago | parent

It’s a real product that we plan to maintain.

toomuchtodo 58 minutes ago | parent

Until the plan changes, which at some point, it will. Comment is still appreciated for what it is.

polishdude20 49 minutes ago | parent

I mean isn't that true for every single thing made by anyone? In that case what more do you want from them?

xandrius 40 minutes ago | parent

Except for things they make: forever maintained forever.

dotancohen 47 minutes ago | parent

This is an Amazon product, not a Google product.

jghn 25 minutes ago | parent

The two have different failure modes.

Google builds up a product over time and abandons it. This is annoying for long term adopters.

AWS has a habit of throwing a bunch of products at the wall, but only bothering to maintain & build up a few of them. This is annoying for early adopters.

llama052 9 minutes ago | parent

Azure on the other hand. Will throw products out, ensure they are never consistent with other offerings on their platform, and then deprecate it from under you while promoting the same thing with a new name.

QGQBGdeZREunxLe 40 minutes ago | parent

Why would you say this? AWS are notorious for maintaining things.

switchbak 32 minutes ago | parent

You're certainly not wrong. But in the wake of Localstack's changes, the landscape has been full of slopware and low trust anyway. I don't think this is worse, for now at least.

sequence7 5 minutes ago | parent

Is there anywhere I can find a matrix of what services are emulated and how complete that emulation is? I tried the docs but just ended up going round in circles.

switchbak 34 minutes ago | parent

In my experience Floci has been the epitome of vibe coded - huge amount of changes, with things breaking randomly between releases. Moved away from it as soon as I could. Still better than Localstack :)

I didn't have a good experience with test containers, but perhaps it'd work better with fast starting containers. We run our test fixture with compose, and have the tests manage their data in isolation - so we don't pay the startup penalty in our test suites.

I think I'd trust this project at least as much as Floci. Embedded Rust mode also looks very interesting for us.

iLoveOncall 27 minutes ago | parent

It has an official documentation on the AWS website, why would you assume it's not a real product? Because it was launched recently?

sebmellen 1 hour ago | parent

RIP LocalStack… can’t say I’d be unhappy to see it go though.

tptacek 1 hour ago | parent

The title for this story should be "aws-emulator, from AWS".

stuff4ben 1 hour ago | parent

Wonder if this could be considered a replacement for Ministack which itself was a vibe-code replacement of Localstack?

BorisMelnik 1 hour ago | parent

looks like ministack made an announcment

pavel_lishin 36 minutes ago | parent

https://ministack.org/blog/aws-emulator

tonymet 1 hour ago | parent

A mere 20 years too late. Now it’s faster to have AI mock your APIs for you. AI has been a boon for test coverage.

Cthulhu_ 52 minutes ago | parent

Which is why they used AI to mock these APIs for you... too? I'd expect Amazon to feed it a lot of internal information so it has more to work with than anything someone else can cook up.

https://www.aboutamazon.com/news/aws/how-autonomous-ai-agent...

tonymet 5 minutes ago | parent

it takes more time for my AI to learn their "emulator" . And I end up with far fewer dependencies on my own.

I've been prompting the agents to build everything using stdlib

gateauxd 1 hour ago | parent

Excited to see this develop and be a free replacement to localstack / similar providers.

aabhay 41 minutes ago | parent

Localstack is almost entirely free. I’ve used it at our company for years without paying.

sequence7 7 minutes ago | parent

Localstack is no longer free and if you’re using it commercially you need to pay for a license. The free plan explicitly states that it is non commercial.

https://blog.localstack.cloud/2026-upcoming-pricing-changes/

BorisMelnik 1 hour ago | parent

ok who's gonna build the GUI / web console on top of it?

awestroke 49 minutes ago | parent

For what? Use the APIs.

mystifyingpoi 30 minutes ago | parent

I could see this being useful. Just let Console pick the localhost:xxxx endpoints for everything, boom, my "own" fake AWS.

swiftcoder 50 minutes ago | parent

I guess they didn't decide this was worth it till they needed it to train an LLM, huh? Not like everyone (inside and outside of AWS) has needed such a test harness for years...

forgotpwd16 50 minutes ago | parent

~30K commits in 3w; quality software for sure. Is someone trying to get promotion by tokenmaxxing? Ironic or unlucky coincidence or competitor(s) misdirection, that, only 2w ago, Amazon published memo discouraging AI abuse?

cxr 49 minutes ago | parent

No idea why there's so much of this lately, but there are way too many editorialized submission titles hitting the front page recently. Please stop doing this.

<https://news.ycombinator.com/newsguidelines.html>

mh- 34 minutes ago | parent

Almost every large thread has upvoted comments that violate the comment guidelines, now, too. In both cases, not enough people flagging them, I guess.

paavohtl 43 minutes ago | parent

Looks like this was ~100% generated with Claude within the past month. Interestingly it still has a lot of occurrences of words that Opus used way too much pre 5.5, so maybe they're not using the latest models.

https://github.com/search?q=repo%3Aaws%2Faws-emulator+load-b...

https://github.com/search?q=repo%3Aaws%2Faws-emulator+%2Fno+...

https://github.com/search?q=repo%3Aaws%2Faws-emulator+golden...

mystifyingpoi 31 minutes ago | parent

Seems like a great fit for LLM - extensive documentation, plus a live system it can probe against freely to match the behavior.

switchbak 28 minutes ago | parent

I mean, if they're using it internally then there's probably a TON of context you can feed these things to converge on approximately-correct solutions. Certainly it sounds like it can be a much better alternative to Localstack/Floci and friends.

whalesalad 14 minutes ago | parent

29,000 commits in a month is crazy

morelandjs 38 minutes ago | parent

Fellow Amazonian here. Want to say that I’m grateful you built this and it has tremendous value if pulled off well and properly maintained.

Agentic development is all about closing off a system as much possible, then mocking up or simulating any inputs or dependencies that cannot be closed off. At that point, you let Claude crawl over the system and do its thing.

This inevitably runs into problems with infrastructure and any tools that help mock up those interfaces will be tremendously valuable. Thank you!

gosen 34 minutes ago | parent

Do I need to get certified to use it?

ggcr 31 minutes ago | parent

Will it be maintained? Or was it more of a toy-project for its large scale agentic blogpost? [0]

[0] https://www.aboutamazon.com/news/aws/how-autonomous-ai-agent...

varispeed 22 minutes ago | parent

Just a little bit more to keep you hooked. You should do your best to stay away from these parasites. Especially if they don't respect your country and your people by not paying the right amount of tax.

Waterluvian 19 minutes ago | parent

If I understand this correctly, it means I can point my entire CDK project to the emulator and test a `cdk deploy`?

I'm curious just how realistic the "internal" behaviour is emulated. It's been a while (since I got my stack working and I just don't like touching it now...), but I recall it being a real pain that sometimes odd, sometimes inconsistent things happened with setup and teardown (even through Terraform), which led to long timeouts if you did things in the wrong (but seemingly valid) order.

andreadito 18 minutes ago | parent

Finally!

__natty__ 12 minutes ago | parent

For me, what is interesting in this project is it's git history.

microflash 8 minutes ago | parent

> AWS Emulator is configured to collect and report usage data to AWS, to gain insight into how AWS Emulator is used. Telemetry is on by default.

They can't help themselves, can they?

I'll stick with Floci and Testcontainers.

toenail 6 minutes ago | parent

Mh, no transfer family service... I wonder what else is missing..