predicate filter action Predicate Filter Action

Provided by: "Apache Software Foundation"

Support Level for this Kamelet is: "Preview"

Filter based on a JsonPath Expression

Configuration Options

The following table summarizes the configuration options available for the predicate-filter-action Kamelet:

Property Name Description Type Default Example

expression *

Expression

The JsonPath Expression to evaluate, without the external parenthesis. Since this is a filter, the expression will be a negation, this means that if the foo field of the example is equals to John, the message will go ahead, otherwise it will be filtered out.

string

"@.foo =~ /.*John/"

Fields marked with an asterisk (*) are mandatory.

Dependencies

At runtime, the predicate-filter-action Kamelet relies upon the presence of the following dependencies:

  • camel:core

  • camel:kamelet

  • camel:jsonpath

Usage

This section describes how you can use the predicate-filter-action.

Knative Action

You can use the predicate-filter-action Kamelet as an intermediate step in a Knative binding.

predicate-filter-action-binding.yaml
apiVersion: camel.apache.org/v1alpha1
kind: KameletBinding
metadata:
  name: predicate-filter-action-binding
spec:
  source:
    ref:
      kind: Kamelet
      apiVersion: camel.apache.org/v1alpha1
      name: timer-source
    properties:
      message: "Hello"
  steps:
  - ref:
      kind: Kamelet
      apiVersion: camel.apache.org/v1alpha1
      name: predicate-filter-action
    properties:
      expression: "@.foo =~ /.*John/"
  sink:
    ref:
      kind: Channel
      apiVersion: messaging.knative.dev/v1
      name: mychannel

Prerequisite

You have Camel K installed on the cluster.

Procedure for using the cluster CLI

  1. Save the predicate-filter-action-binding.yaml file to your local drive, and then edit it as needed for your configuration.

  2. Run the action by using the following command:

    kubectl apply -f predicate-filter-action-binding.yaml

Procedure for using the Kamel CLI

Configure and run the action by using the following command:

kamel bind timer-source?message=Hello --step predicate-filter-action -p "step-0.expression=@.foo =~ /.*John/" channel:mychannel

This command creates the KameletBinding in the current namespace on the cluster.

Kafka Action

You can use the predicate-filter-action Kamelet as an intermediate step in a Kafka binding.

predicate-filter-action-binding.yaml
apiVersion: camel.apache.org/v1alpha1
kind: KameletBinding
metadata:
  name: predicate-filter-action-binding
spec:
  source:
    ref:
      kind: Kamelet
      apiVersion: camel.apache.org/v1alpha1
      name: timer-source
    properties:
      message: "Hello"
  steps:
  - ref:
      kind: Kamelet
      apiVersion: camel.apache.org/v1alpha1
      name: predicate-filter-action
    properties:
      expression: "@.foo =~ /.*John/"
  sink:
    ref:
      kind: KafkaTopic
      apiVersion: kafka.strimzi.io/v1beta1
      name: my-topic

Prerequisites

  • You’ve installed Strimzi.

  • You’ve created a topic named my-topic in the current namespace.

  • You have Camel K installed on the cluster.

Procedure for using the cluster CLI

  1. Save the predicate-filter-action-binding.yaml file to your local drive, and then edit it as needed for your configuration.

  2. Run the action by using the following command:

    kubectl apply -f predicate-filter-action-binding.yaml

Procedure for using the Kamel CLI

Configure and run the action by using the following command:

kamel bind timer-source?message=Hello --step predicate-filter-action -p "step-0.expression=@.foo =~ /.*John/" kafka.strimzi.io/v1beta1:KafkaTopic:my-topic

This command creates the KameletBinding in the current namespace on the cluster.