predicate filter action Predicate Filter Action

Provided by: "Apache Software Foundation"

Support Level for this Kamelet is: "Stable"

Filter based on a JsonPath Expression. 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.

Configuration Options

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

Property Name Description Type Default Example

expression

Expression

Required 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/

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 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 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.

Kamelet source file

https://github.com/apache/camel-kamelets/blob/main/kamelets/predicate-filter-action.kamelet.yaml

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