BusEnvironmentPostProcessor rebuilds Bus Stream bindings from bootstrap-visible config on refresh, not from application.yml

[AynurMuftakhov]

Hello,

I found what looks like a refresh inconsistency around spring.cloud.bus.destination when bootstrap is enabled.

I am not fully sure whether this is intended bootstrap-related behavior or a bug, but the result is surprising: the property works correctly at startup from application.yml, yet after refresh the derived Bus Stream binding destinations are rebuilt differently.

Versions

• Spring Boot: 3.5.11
• Spring Cloud: 2025.0.0
• spring-cloud-bus: 4.3.0
• spring-cloud-stream: 4.3.0

Sample project

Minimal reproducer:

https://github.com/AynurMuftakhov/demo-bus

Observed cases

Case 1 — spring.cloud.bus.destination only in application.yml
Startup is correct, but refresh is wrong.

Case 2 — move only spring.cloud.bus.destination to bootstrap.properties
Startup is correct, and refresh is also correct.

Case 3 — keep spring.cloud.bus.destination in application.yml, but explicitly set spring.cloud.stream.bindings.*.destination
Startup is correct, and refresh is also correct.

Problem summary

With spring-cloud-starter-bootstrap enabled:

• if spring.cloud.bus.destination is defined only in application.yml, startup works correctly
• but after refresh, the derived properties
  spring.cloud.stream.bindings.springCloudBusInput.destination and
  spring.cloud.stream.bindings.springCloudBusOutput.destination
  are reset to the default value springCloudBus

As a result, after refresh and rebinding, publishing starts using the default exchange instead of the custom one.

Expected behavior

If spring.cloud.bus.destination is defined in application.yml and works at startup, I would expect refresh to preserve or recompute the same Bus-derived Stream binding destinations consistently.

At minimum, if this is expected behavior with bootstrap enabled, it would be helpful to document clearly that spring.cloud.bus.destination must be bootstrap-visible for refresh-time reconstruction.

Additional observation

From debugging, BusEnvironmentPostProcessor is invoked during refresh, but only in the bootstrap-related refresh path.

That means:

• properties from bootstrap.properties are seen and applied
• properties from application.yml are not used to rebuild the Bus-derived Stream binding destinations

Question

Is it expected that with bootstrap enabled, spring.cloud.bus.destination must be in bootstrap.properties for refresh to rebuild Bus-derived Stream binding destinations correctly?

If not, should refresh also rebuild these derived properties from application.yml?

Thank you.

[ryanjbaxter]

In case #1 do you also have spring-cloud-starter-bootstrap on the classpath? And if so if you remove spring-cloud-starter-bootstrap from the classpath does refresh work properly?

[AynurMuftakhov]

Hi, @ryanjbaxter
Yes, we have spring-cloud-starter-bootstrap on the classpath, and without it, refresh works fine. The problem is relevant only in the setup with a legacy bootstrap context