Funqy Knative Events Binding

To complete this guide, you need:

Setting up Knative locally in a Minikube environment is beyond the scope of this guide. It is advised to follow this Knative Tutorial put together by Red Hat. It walks through how to set up Knative on Minikube or OpenShift in a local environment.

The Cloud Event specification is a good read to give you an even greater understanding of Knative Events.

Clone the Git repository: git clone https://github.com/quarkusio/quarkus-quickstarts.git, or download an archive.

The solution is located in the funqy-knative-events-quickstart directory.

The quickstart works by manually sending an HTTP request containing a Cloud Event to the Knative Broker using curl. The Knative Broker receives the request and triggers the startup of the Funqy container built by the quickstart. The event triggers the invocation of a chain of Funqy functions. The output of one function triggers the invocation of another Funqy function.

When living within a Knative Events environment, Funqy functions are triggered by a specific Cloud Event type. You can have multiple Funqy functions within a single application/deployment, but they must be triggered by a specific Cloud Event Type. The exception to this rule is if there is only one Funqy function in the application. In that case, the event is pushed to that function irregardless of the Cloud Event type.

Currently, Funqy can only consume JSON-based data. It supports both Binary and Structured mode of execution, but the data component of the Cloud Event message must be JSON. This JSON must also be marshallable to and from the Java parameters and return types of your functions.

Let’s start looking at our quickstart code so that you can understand how Knative Events map to Funqy. Open up SimpleFunctionChain.java

The first function we’ll look at is defaultChain.

As is, a Funqy function has a default Cloud Event mapping. By default, the Cloud Event type must match the function name for the function to trigger. If the function returns output, the response is converted into a Cloud Event and returned to the Broker to be routed to other triggers. The default Cloud Event type for this response is the function name + .output. The default Cloud Event source is the function name.

So, for the defaultChain function, the Cloud Event type that triggers the function is defaultChain. It generates a response that triggers a new Cloud Event whose type is defaultChain.output and the event source is defaultChain.

While the default mapping is simple, it might not always be feasible. You can change this default mapping through configuration. Let’s look at the next function:

The configChain function has its Cloud Event mapping changed by configuration within application.properties.

In this case, the configuration maps the incoming Cloud Event type defaultChain.output to the configChain function. The configChain function maps its response to the annotated Cloud Event type, and the Cloud Event source configChain.

The Funqy Knative Events extension also has annotations to do this Cloud Event mapping to your functions. Take a look at the annotatedChain method

If you use the @CloudEventMapping annotation on your function you can map the Cloud Event type trigger and the Cloud Event response. In this example the annotatedChain function will be triggered by the annotated Cloud Event type and the response will be mapped to a lastChainLink type and annotated Cloud Event source.

So, if you look at all the functions defined within SimpleFunctionChain you’ll notice that one function triggers the next. The last function that is triggered is lastChainLink.

There are two things to notice about this function. One, it has no output. Your functions are not required to return output. Second, there is an additional event parameter to the function.

If you want to know additional information about the incoming Cloud Event, you can inject the io.quarkus.funqy.knative.events.CloudEvent interface using the Funqy @Context annotation. The CloudEvent interface exposes information about the triggering event.

If you look at the POM, you’ll see that it is a typical Quarkus POM that pulls in one Funqy dependency:

Funqy Knative Events support dev mode and unit testing using RestAssured. You can invoke on Funqy Knative Events functions using the same invocation model as Funqy HTTP using normal HTTP requests, or Cloud Event Binary mode, or Structured Mode. All invocation modes are supported at the same time.

So, if you open up the unit test code in FunqyTest.java you’ll see that its simply using RestAssured to make HTTP invocations to test the functions.

Funqy also works with Quarkus Dev mode!

First build the Java artifacts:

Next, a docker image is required by Knative, so you’ll need to build that next:

Make sure to replace yourAccountName with your docker or quay account name when you run docker build. The Dockerfile is a standard Quarkus dockerfile. No special Knative magic.

Push your image to docker hub or quay

Again, make sure to replace yourAccountName with your docker or quay account name when you run docker push.

The first step is to set up the broker in our namespace. Following is an example command from the Knative cli.

The broker we have created is called default, this broker will receive the cloud events. The broker is also referenced in the function YAML files.

The second step is to define a Kubernetes/OpenShift service to point to the Docker image you created and pushed during build. Take a look at funqy-service.yaml

This is a standard Kubernetes service definition YAML file.

For our quickstart, one Kubernetes service will contain all functions. There’s no reason you couldn’t break up this quickstart into multiple different projects and deploy a service for each function. For simplicity, and to show that you don’t have to have a deployment per function, the quickstart combines everything into one project, image, and service.

Deploy the service:

The next step is to deploy Knative Event triggers for each of the event types. As noted in the code section, each Funqy function is mapped to a specific Cloud Event type. You must create Knative Event triggers that map a Cloud Event and route it to a specific Kubernetes service. We have 4 different triggers.

defaultChain-trigger.yaml

The spec:filter:attributes:type maps a Cloud Event type to the Kubernetes service defined in spec:subscriber:ref. When a Cloud Event is pushed to the Broker, it will trigger the spin up of the service mapped to that event.

There’s a trigger YAML file for each of our 4 Funqy functions. Deploy them all:

You’ll need two different terminal windows. One to do a curl request to the Broker, the other to watch the pod log files, so you can see the messages flowing through the Funqy function event chain.

Make sure you have the stern tool installed. See the Knative Tutorial setup for information on that. Run stern to look for logs outputted by our Funqy deployment

Open a separate terminal. You’ll first need to learn the URL of the broker. Execute this command to find it.

This will provide you a URL similar to e.g.: http://broker-ingress.knative-eventing.svc.cluster.local/knativetutorial/default. Remember this URL.

Next thing we need to do is ssh into our Kubernetes cluster so that we can send a curl request to our broker. The following command will create a simple OS pod so we can curl into our functions.

You might need to wait a couple of seconds until the curler pod comes up. Run the following to get bash access to the curler pod:

You will now be in a shell within the Kubernetes cluster. Within the shell, execute this curl command , the broker address is an example and might differ based on your project or broker name.

This posts a Knative Event to the broker, which will trigger the defaultChain function. As discussed earlier, the output of defaultChain triggers an event that is posted to configChain which triggers an event posted to annotatedChain then finally to the lastChainLink function. You can see this flow in your stern window. Something like this should be outputted.