Apache Camel source

These samples show how to configure a Camel source. It is a event source that can leverage one of the 250+ Apache Camel components for generating events.

Prerequisites

  1. Install Knative Serving and Eventing.

  2. Install the Apache Camel K Operator in any namespace where you want to run Camel sources.

The preferred version that is compatible with Camel sources is Camel K v0.2.0.

Installation instruction are provided on the Apache Camel K Github repository. Documentation includes specific instructions for common Kubernetes environments, including development clusters.

  1. Install the Camel Source from the camel.yaml in the Eventing Sources release page:
   kubectl apply --filename camel.yaml

Create a Channel and a Subscriber

In order to check if a CamelSource is fully working, we will create:

  • a simple Knative event display service that prints incoming events to its log
  • a in-memory channel named camel-test that will buffer events created by the event source
  • a subscription to direct events from the test channel to the event display service

Deploy the display_resources.yaml:

kubectl apply --filename display_resources.yaml

Run a CamelSource using the Timer component

The simplest example of CamelSource, that does not require additional configuration, is the "timer" source.

If you want, you can customize the source behavior using options available in the Apache Camel documentation for the timer component. All Camel components are documented in the Apache Camel github repository.

Install the source_timer.yaml resource:

kubectl apply --filename source_timer.yaml

We will verify that the published events were sent into the Knative eventing system by looking at what is downstream of the CamelSource.

kubectl logs --selector serving.knative.dev/service=camel-event-display -c user-container

If you've deployed the timer source, you should see log lines appearing every 3 seconds.

Run a CamelSource using the Telegram component

Another useful component available with Camel is the Telegram component. It can be used to forward messages of a Telegram chat into Knative channels as events.

Before using the provided Telegram CamelSource example, you need to follow the instructions on the Telegram website for creating a Telegram Bot. The quickest way to create a bot is to contact the Bot Father, another Telegram Bot, using your preferred Telegram client (mobile or web). After you create the bot, you'll receive an authorization token that is needed for the source to work.

First, download and edit the source_telegram.yaml file and put the authorization token, replacing the <put-your-token-here> placeholder.

To reduce noise in the event display, you can remove the previously created timer CamelSource from the namespace:

kubectl delete camelsource camel-timer-source

Install the source_telegram.yaml resource:

kubectl apply -f source_telegram.yaml

Now, you can send messages to your bot with any Telegram client.

Check again the logs on the event display:

kubectl logs --selector serving.knative.dev/service=camel-event-display -c user-container

Each message you send to the bot will be printed by the event display as a cloudevent.