Cloudflare K2: serverless event streams

Cloudflare K2: serverless event streams(blog.cloudflare.com)

92 points by elffjs 4 hours ago | 27 comments

psanford 1 hour ago |

Object store is quickly becoming the new core data substrate. Lets build kafka, but on s3. Lets build github, but on s3. It feels like we going to see more and more "object-store first" systems in the next few years.

I am excited about this future. Give me stateless servers and a storage bucket over having to manage systems with disks any day.

I do wonder if we will see an expansion of the s3 api to support more of these use cases. S3 added a janky file append operation to their new express-one-zone bucket type, and limited to 10k total file append operations. I wonder what else we will get in the next few years.

khazit 7 minutes ago | |

I still think S3 is underutilized.

The range of things you can do with blob storage and a (very simple) auth model are surprisingly broad.

We recently replaced our Docker container registry with S3 using a tiny tool [1] we built in-house. I think that even with current capabilities, we can still model a lot services as a very thin layer over object storage.

[1]: https://github.com/Simple-Observability/grue

necubi 1 hour ago | |

Definitely agree that every data system that doesn't need <100ms latency is moving to object storage.

> I do wonder if we will see an expansion of the s3 api to support more of these use cases

This is actually an area where I think we have a big leg up on folks building on top of S3. My team (which built K2) sits next to the R2 team, and we have the opportunity to co-evolve the products in mutually beneficial ways.

6thbit 1 hour ago | |

doesn't that make egress fees egregious? or still cheaper than disks?

cj 41 minutes ago | | |

You can download objects from S3 from EC2 without traversing the public internet using things like gateway endpoints [0] which avoids s3 egress fees. But doesn't avoid egress fees from EC2 to the end user.

[0] https://docs.aws.amazon.com/vpc/latest/privatelink/vpc-endpo...

vmg12 1 hour ago | | |

This all depends on the cloud you are building on and if the data ever leaves the datacenter.

Onavo 1 hour ago | |

People like S3 because they have hard engineering guarantees around bit rot and work well as a high level abstraction of a network filesystem with all of the low level failure recovery built-in. You don't have to worry about doing your own RAID configs. The bigger question is whether non-AWS services can offer the same level of guarantees. I have heard horror stories for example when it comes to downtime on Hetzner's S3 object store.

I am currently using Cloudflare R2 right now and if you see their forums, there's always the occasional post about objects going missing.

sgt 21 minutes ago | | |

Meanwhile, just using disks and regular servers is still reliable and more so than ever, especially with some redundancy.

Consider your cloud costs.

addisonj 35 minutes ago |

Congrats on the launch! Stream/event-based system are really powerful, but they are also just pretty complex, in no small part because the modeling of streams for most people today is really modeling Kafka topic/partitions which has a whole bunch of foot-guns and complexity. Making the individual stream really cheap and easy is a big simplification, especially if flexibly consuming a stream for both ordered and unordered use-cases is made simple. This looks to work for unordered, be curious to see how the managed dividing the work for the mentioned key-based ordering.

loufe 2 hours ago |

If I was a serious Cloudflare customer I would be seriously concerned about the security of my infrastructure with them. Yes LLMs can code fast but this is an almost frenetic pace of releasing new products, all with fewer staff.

wqtz 34 minutes ago | |

I trust that this is not the case. Check out both the authors. Micah's company was acquired by Cloudflare, and both of these guys actually bring good expertise around this area.

The question is less about "vibe coding" the product, and more about how their acquired teams function. For most products they have released so far, they are backed by a company they acqui-hired. They will usually rebrand the product and absorb the team.

You would not be surprised if this release was from a product for a startup company rather than a large enterprise company.

Cloudflare hired a bunch of folks for sure, but they also fired a lot of folks. What they are doing these days is building products by buying out entire companies, giving them nearly independent authority to build a product like they would build a company.

owenthejumper 48 minutes ago | |

They've always been this fast. The trick is that they release beta products a lot. Kind of classic "lean" (does anyone remember that?)

My bigger concern would be their increasing grip on a lot of the market, and eventually becoming a monopoly (or part of the big tech "duopoly")

sssilver 10 minutes ago | | |

> eventually becoming a monopoly (or part of the big tech "duopoly")

At this point this has already effectively happened. The average person doesn't realize the extent of it, because the products Cloudflare builds are inherently transparent to the average consumer.

vmg12 2 hours ago | |

They are working on a set of primitives that make building this kind of software easier. With AI, runtimes matter more than ever and languages matter less.

threatofrain 2 hours ago | |

I find this release relieving because it fills a hole that was really needed. Another hole would be a proper database and improvements to D1.

NicoJuicy 2 hours ago | |

That's just perception. At the same time they were hiring 1 k. People and hired 2 k. People the year before ( interns).

There was just more news about it than with other companies ( I think they let go about 2 k. People a year ago).

( Not saying it's good, just a little perception balance)

necubi 2 hours ago |

I'm the author of the post and tech lead for K2. Happy to answer any questions!

samtp 1 minute ago | |

After reading the post, still don't fully understand when you would use CF Queues vs K2. Can you help to elaborate a bit more?

aniketsauravv 1 hour ago | |

Great product, congratulation on launch. Are you using this internally in any way?

necubi 1 hour ago | | |

Yes! We originally built K2 to serve as the ingestion layer for Basin Pipelines [0], our stream processing product. We have a number of other teams building new products on top of it at the moment which I can't talk about yet :)

[0] https://developers.cloudflare.com/basin-pipelines/

kirillkosolapov 55 minutes ago |

How does this solution differ from AutoMQ and WarpStream? I’ve worked with one of them, and it is indeed a serverless solution built on top of S3.

As far as I know, Kafka itself already supports offloading some data to S3 for long-term storage.

Based on the articles—which I didn't fully grasp—I’m wondering if there are additional benefits mentioned, such as multi-region distribution (though I find it hard to imagine how that would be implemented).

thepaulmcbride 1 hour ago |

This sounds like a super interesting product, but I'm always reluctant to build on anything that isn't a portable industry standard.

ameliaquining 1 hour ago | |

Presumably the Kafka-compatible API that they say is in the works will address this?

necubi 1 hour ago | | |

Yep. I'm not personally a huge fan of the kafka API — I think it's simultaneously too low level for normal users and too high level to deeply integrate into other systems (like stream processing engines), and requires a complex client library to use effectively.

We went with a simpler and more user friendly consume API, that also allows much higher levels of read parallelism (particularly important if you're using something like Workers, which parallelize well but aren't very powerful individually).

But we know many companies are invested in the Kafka ecosystem, and we want to provide an easy on (and if necessary, off) ramp for them.

theredsix 2 hours ago |

What's the benefits of this over traditional GKE pub/sub, kafka or another queuing service?

necubi 1 hour ago | |

Google PubSub is a great product. The primary benefit of K2 is cost, particularly for longer retention periods. Being backed by object storage means that we can store data extremely cheaply compared to disk backed solution, and we pass that on in our pricing.

Compared to self-hosted or cloud-hosted Kafka (e.g., Amazon MSK or Confluent), K2 is much cheaper, and fully serverless. There are no clusters to manage or scale, and consistent performance even as you vastly increase the amount of data.

The main downside is produce (and end to end) latency is higher (around 1s p99) than systems that rely on local disk replication, like Kafka.

So it's great if you're trying to move a huge amount of data around, or for use cases where cost is more important than latency.

freakynit 1 hour ago | |

Ha setup and management is costly. K2 relieves you off that by charging you 0.04/0.04/GB read/write and 0.02/GB/month storage. Pretty useful if your volume is not into multi-GB's a month. GKE pub/sub seems pretty costly by comparison.

ipkstef 1 hour ago |

i was trying to understand why i would use this over their current offerings of queues, and im really sick so my brain isn't working. so i ran it through ai

  You need...                                            | Use
  -------------------------------------------------------|-------
  “Make sure this job gets done”                         | Queue
  retries / dead-letter handling                         | Queue
  delayed jobs                                           | Queue
  distribute jobs among workers                          | Queue
  “Record that this event happened”                      | K2
  multiple independent systems reading the same events   | K2
  replay old events                                      | K2
  ordered event streams                                  | K2
  Kafka-like architecture                                | K2

You need... | Use -------------------------------------------------------|------- “Make sure this job gets done” | Queue retries / dead-letter handling | Queue delayed jobs | Queue distribute jobs among workers | Queue “Record that this event happened” | K2 multiple independent systems reading the same events | K2 replay old events | K2 ordered event streams | K2 Kafka-like architecture | K2