AWS recently announced enhanced custom event buses for Amazon EventBridge, allowing organizations to share a centralized bus across accounts with ordered delivery, simplified subscriber management, event replay, content-based deduplication, and a new publisher/subscriber-based pricing model.
EventBridge is a managed event bus service for routing events between distributed applications and AWS services. As adoption grows across multi-account environments, teams often need multiple interconnected event buses, increasing routing costs and operational complexity while making event subscriptions harder to manage and features such as ordering more difficult to implement. Micah Walter, senior solutions architect at AWS, writes:
This workaround reintroduces the operational complexity that serverless architectures are meant to eliminate. Platform teams lose visibility into who is subscribing to which events, cross-account and bus-to-bus routing charges compound quickly, and teams that need capabilities like event ordering are forced to build complex workarounds or adopt entirely different technologies.
The enhanced EventBridge custom event bus provides a shared, organization-wide bus with cross-account publishing and subscriptions, ordered delivery, event replay, content-based deduplication, JSONata-based event transformation, and support for Avro and Protobuf payloads.
A new Subscriber resource combines filtering, targets, retries, and dead-letter handling, while ingress/egress throughput pricing separates publisher and subscriber costs. Describing it as "the biggest EventBridge launch since the service introduction in July 2019," Jamie Dool, principal product manager at AWS, writes:
Some decisions we made way back then are hard to evolve as the world of event-driven architectures has evolved (...) we relaunch the original custom event bus resource. Built from the ground up on a new architecture that delivers the capabilities, scale, and cost that let customers build resilient distributed systems from day one.
The community reaction has been overwhelmingly positive, with some praising the simplified architecture and others the new features. Gregor Hohpe, "architect elevator" and former director of enterprise strategy at AWS, writes:
Almost like Kafka but big step ahead, aside, perhaps, of the naming, which is in good tradition.
In his newsletter, Corey Quinn, chief cloud economist at The Duckbill Group, reviews the costs:
This is a delightful improvement, only marred by its positioning as "being for enterprise." I didn't realize I was an enterprise, because I have an AWS estate that is about to massively benefit from this thing. Even the pricing, clocking in at a somewhat hefty 18¢ per GB ingested, isn't particularly "Enterprise." It's high, but not unreasonable unless you're doing something profoundly weird with EventBridge.
Enhanced custom event buses use ingress and egress throughput pricing, with publishers charged for ingested events and subscribers for delivered events. Existing custom event buses remain unchanged, while enhanced custom event buses are available as a new resource.