|
1 | 1 | # Trigger |
2 | 2 |
|
3 | | -TODO |
| 3 | +Triggers objects build subscriptions from Brokers to event consumers. A Trigger contains 3 elements: broker reference, target and filter. |
| 4 | + |
| 5 | +- The referenced broker will be reconfigured to address for the new subscription. |
| 6 | +- The target must be set to either a Kubernetes object that can be resolved to an URL, or a URL. In either case the target must expose an HTTP endpoint to receive events. |
| 7 | +- The filter declaratively selects which events should be forwarded to the target. In absence of filter all messages received at the Broker will be sent to the configured Target. |
| 8 | + |
| 9 | +## Spec |
| 10 | + |
| 11 | +```yaml |
| 12 | +apiVersion: eventing.triggermesh.io/v1alpha1 |
| 13 | +kind: Trigger |
| 14 | +metadata: |
| 15 | + name: <trigger name> |
| 16 | +spec: |
| 17 | + broker: |
| 18 | + apiVersion: <Kubernetes apiVersion for the Broker object. Can inform 'group' instead> |
| 19 | + group: <Kubernetes group for the Broker object. Can inform 'apiVersion' instead> |
| 20 | + kind: <Kubernetes kind for the Broker object> |
| 21 | + name: <name of the Broker object> |
| 22 | + target: <Destination where events will be sent. Either reference to an objet or URI> |
| 23 | + ref: |
| 24 | + apiVersion: <Kubernetes apiVersion for the consumer object. Can inform 'group' instead> |
| 25 | + group: <Kubernetes group for the consumer object. Can inform 'apiVersion' instead> |
| 26 | + kind: <Kubernetes kind for the consumer object> |
| 27 | + name: <name of the consumer object> |
| 28 | + uri: <URI to the event consumer HTTP endpoint> |
| 29 | + delivery: <Event delivery options> |
| 30 | + retry: <Number of tries to deliver an event before considering failed> |
| 31 | + backoffDelay: <Backoff duration factor between retries> |
| 32 | + backoffPolicy: <Backoff policy applied to the delay, can be linear, exponential or constant> |
| 33 | + deadLetterSink: <Destination where underlivered events will be sent> |
| 34 | + ref: |
| 35 | + apiVersion: <Kubernetes apiVersion for the DLS object. Can inform 'group' instead> |
| 36 | + group: <Kubernetes group for the DLS object. Can inform 'apiVersion' instead> |
| 37 | + kind: <Kubernetes kind for the DLS object> |
| 38 | + name: <name of the DLS object> |
| 39 | + uri: <URI to the event DLS HTTP endpoint> |
| 40 | + filters: <Filter specification. See 'Filtering Events' section in this doc> |
| 41 | +``` |
| 42 | +
|
| 43 | +- `spec.broker` must be a running broker that will be configured with this Trigger's configuration. |
| 44 | +- `spec.target` must refer to an endpoint that will receive events from the Broker. When the event consumer is a Kubernetes object it is prefered to use the `spec.target.ref` structure. |
| 45 | +- `spec.delivery` contains the logic to apply when an event cannot be delivered from the Broker to a Target, performing a number of retries, and finally sending to a dead letter sink if none of them succeed. Duration format for `spec. |
| 46 | +- `spec.filters` contain a set of filter expresions. See the [Filtering Events section](#filtering-events) |
| 47 | + |
| 48 | +## Filtering Events |
| 49 | + |
| 50 | +Events flowing through a Broker can be filtered before being sent to targets by using a range of expressions. TriggerMesh filter supports the [CloudEvents Subscriptions API filters](https://github.com/cloudevents/spec/blob/main/subscriptions/spec.md#324-filters), but will extend it with custom _dialects_ in the future. |
| 51 | + |
| 52 | +There are 2 categories of filter dialects, those that perform actual filtering and those that group other dialects adding boolean logic to the inner dialects: |
| 53 | + |
| 54 | +These filter dialects are meant to group inner dialects: |
| 55 | + |
| 56 | +- `all` contains an array of dialects, all of them must resolve to true for positive matching. |
| 57 | +- `any` contains an array of dialects, at least one of them must resolve to true for positive matching. |
| 58 | +- `not` contains an array of dialects, all of them must resolve to false for positive matching. |
| 59 | + |
| 60 | +These filter dialects contain matching logic applied to the [CloudEvent attributes](https://github.com/cloudevents/spec/blob/v1.0.2/cloudevents/spec.md#context-attributes): |
| 61 | + |
| 62 | +- `exact` contains a key/value pair. For positive matching an attribute by that key/value must exist at the event. |
| 63 | +- `prefix` contains key/value pair. For positive matching an attribute by the exact key that contains a value that is prefixed by the one at the filter must exist at the event. |
| 64 | +- `suffix` contains a key/value pair. For positive matching an attribute by the exact key that contains a value that is suffixed by the one at the filter must exist at the event. |
| 65 | + |
| 66 | +### Examples |
| 67 | + |
| 68 | +Filter for events whose `type` attribute is set to `io.triggermesh.demo` |
| 69 | + |
| 70 | +```yaml |
| 71 | +filters: |
| 72 | +- exact: |
| 73 | + type: my.demo.type |
| 74 | +``` |
| 75 | + |
| 76 | +Filter for events whose `type` attribute is set to `io.triggermesh.demo` and `category` is set to `test` |
| 77 | + |
| 78 | +```yaml |
| 79 | +filters: |
| 80 | +- all: |
| 81 | + - exact: |
| 82 | + type: io.triggermesh.demo |
| 83 | + - exact: |
| 84 | + category: test |
| 85 | +``` |
| 86 | + |
| 87 | +Filter for events whose `type` attribute starts with `io.triggermesh.` or `type` is set to `io.tm.demo` |
| 88 | + |
| 89 | +```yaml |
| 90 | +filters: |
| 91 | +- any: |
| 92 | + - prefix: |
| 93 | + type: io.triggermesh. |
| 94 | + - exact: |
| 95 | + type: io.tm.demo |
| 96 | +``` |
| 97 | + |
| 98 | +Filter for events whose `type` attribute does not ends with `.avoid.me` or `.avoid.me.too`. |
| 99 | + |
| 100 | +```yaml |
| 101 | +filters: |
| 102 | +- not: |
| 103 | + - any: |
| 104 | + - suffix: |
| 105 | + type: .avoid.me |
| 106 | + - suffix: |
| 107 | + type: .avoid.me.too |
| 108 | +``` |
0 commit comments