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.
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.
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.
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.
Nothing personal, but unless you can link us to a public announcement made by Amazon, your statement is worth less than nothing.
Official statements made by a company are still poor representations of their current business plans, and don't mean anything 3 months later (no matter how much they pinky promise). But a HN post isn't even that.
Additionally Swami, our SVP of AI blogged about it separately and our CTO is tweeting about it - which is more than a number of products get in terms of coverage.
I didn't mean announcing the tool, I meant an announcement committing to the maintenance/support that users like the GP poster were looking for. My bad on describing that clearly, I'm gonna get clowned on in the comments and I'm not turning this around.
I understood what you meant. I was just trying to add evidence to support my claim that it was a real product and would be maintained. And yeah, votes on comments can be fickle.
GP statement still stands, actually being strengthened. This blog post doesn't even mention nor seems to care about maintainability or long-term support or anything that users will care about. Only talks about how cool the team is and how amazing they're at using AI, multi-agent workflows, and this kind of bs. It's funny how author talks so much about testing when they themselves also boast how they haven't written or reviewed any of the code.
This site is riddled with companies and commenters officially representing massive entities that go back on their promises. Are you saying that we should trust them just because they represent their company?
Strongly agree. I've been wanting an official emulator from AWS for years. It looks like they've finally produced it, and it looks like somebody that works there is saying they're planning on maintaining it. And they've blogged that it was released. And somehow the comments are focusing on the fact that they haven't promised to maintain it for a long time. It's extremely rare to ever see statements about longevity when something is first announced.
We can appreciate it while also recognizing that history repeats itself into disappointment while also recognizing that Amazon has done large social media campaigns (remember the FC Ambassadors?). I would have been more excited about this ten years ago.
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.
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.
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.
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!
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.
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.
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.
~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?
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...
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.
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.
Their business isnt making software, its providing compute. Thats not automatable until we have physical AI driven robots mining silicon and turning them into chips to put in datacenters
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/
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.
Official statements made by a company are still poor representations of their current business plans, and don't mean anything 3 months later (no matter how much they pinky promise). But a HN post isn't even that.
That said, it’s been announced publicly here: https://www.aboutamazon.com/news/aws/how-autonomous-ai-agent...
Additionally Swami, our SVP of AI blogged about it separately and our CTO is tweeting about it - which is more than a number of products get in terms of coverage.
Can we just appreciate that they _appear_ to be doing the right thing here? Save the criticism for when (if?) they turn their backs.
I appreciate the effort dang and team have put into keeping the quality high here over the years, and I'm not sure what the optimal solution is.
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.
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.
<https://news.ycombinator.com/newsguidelines.html>
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!
https://blog.localstack.cloud/2026-upcoming-pricing-changes/
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...
They can't help themselves, can they?
I'll stick with Floci and Testcontainers.
[0] https://www.aboutamazon.com/news/aws/how-autonomous-ai-agent...
https://www.aboutamazon.com/news/aws/how-autonomous-ai-agent...
I've been prompting the agents to build everything using stdlib
“Claude, make my LLC into the largest global logistics business and largest U.S. cloud provider overnight. Thanks.”
Nevermind the massive logistics and network infrastructure, enormous market position, etc.
Sure, you can build something in a few days. Replicating their business model? Yeah. No.
Call me when Claude can design, manufacture, ship, and build a data centre.