[BROOKLYN-278] default Propagator enricher can cause infinite subscription event loop

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.10.0
• Assignee: Unassigned
• Reporter: Aled Sage
• Created: 23/May/16 13:18
• Updated: 27/May/16 11:07
• Resolved: 24/May/16 16:10

Description

The default Propagator can cause an infinite loop: it subscribes to all sensor events from that entity, and republishes them!

For example, the blueprint below demonstrates this:

location: localhost
services:
- type: org.apache.brooklyn.entity.stock.BasicApplication
  brooklyn.enrichers:
  - type: org.apache.brooklyn.enricher.stock.Propagator

This shows repeated log messages like:

2016-05-23 14:09:09,069 DEBUG o.a.b.c.entity.AbstractEntity [brooklyn-execmanager-B5OU5RXp-6]: Emitting sensor notification entity.location.added value LocalhostMachineProvisioningLocation{id=U27ANQ3v, name=localhost} on BasicApplicationImpl{id=C8KeD18W}

I'd expect such missing propagator config to cause it to fail. Or if it was misconfigured to cause an infinite loop, then that would also cause a failure.

For example, the blueprint below also produces an infinite loop and should be forbidden:

location: localhost
services:
- type: org.apache.brooklyn.entity.stock.BasicApplication
  id: app
  brooklyn.enrichers:
  - type: org.apache.brooklyn.enricher.stock.Propagator
    brooklyn.config:
      producer: $brooklyn:entity("app")
      propagatingAll: true

Issue Links

• links to: GitHub Pull Request #154