Trigger filters

Events flowing through a Broker can be filtered before being sent to targets by means of Trigger filters. TriggerMesh filters are based on the CloudEvents Subscriptions API filters, which allow for fairly complex filtering against event metadata, known as CloudEvent context attributes. Filters are not supported for the event payload (i.e. the data attribute of an event). Content-based filtering of entire payload will be added in the future.

As described below, TriggerMesh on Kubernetes provides full control over Trigger filters through its Kubernetes CRD. On the other hand, tmctl provides a simpler abstraction over filters as described in the Trigger documentation.

Filter operators

Filter operators fall under two categories: string matching functions exact, prefix and suffix, and logical operators all, any and not to combine them. The string matching functions can be used at the root of the filters attribute without requiring a logical operator.

• exact: the key must exist and exactly match the provided value
• prefix the key must exist and the value include the provided value as a prefix
• suffix the key must exist and the value include the provided value as a suffix
• all all operators must evaluate to true
• any at least one operator must evaluate to true
• not all operators must evaluate to false

Examples

Filter for events whose type attribute is set to io.triggermesh.demo

filters:
- exact:
    type: my.demo.type

Filter for events whose type attribute is set to io.triggermesh.demo and category is set to test

filters:
- all:
  - exact:
      type: io.triggermesh.demo
  - exact:
      category: test

Filter for events whose type attribute starts with io.triggermesh. or type is set to io.tm.demo

filters:
- any:
  - prefix:
      type: io.triggermesh.
  - exact:
      type: io.tm.demo

Filter for events whose type attribute does not ends with .avoid.me or .avoid.me.too.

filters:
- not:
  - any:
    - suffix:
        type: .avoid.me
    - suffix:
        type: .avoid.me.too