Building with the new EventBridge custom event buses

Overview

The new EventBridge custom event bus routes events and retains them. You publish with one of two APIs, and subscribers filter, optionally transform, and deliver each matching event to one target.

Read chapters 5 and 6 before writing any filter, transformer, or target parameter. The two publish APIs deliver different payload shapes, and an expression written for one silently matches nothing against the other.

Publish metrics are on by default, so you can always tell whether events reached a bus. Subscriber logs are off by default, so turn them on before you debug a delivery rather than after (chapter 18).

Works best with the AWS MCP server, which is recommended for running the CLI calls in this skill: it executes them in a sandboxed environment with audit logging. All guidance also works with standard AWS CLI access.

Conventions