Kogito Serverless Workflow - Knative custom function

Description

This example contains a simple workflow service that illustrates how to use Serverless Workflow custom function to invoke Knative services.

This example consists of a workflow and a remote service that both will be deployed to Knative.

The service is described using JSON format as defined in the CNCF Serverless Workflow specification.

Installing and Running

Prerequisites

You will need:

Java 11+ installed
Environment variable JAVA_HOME set accordingly
Maven 3.8.6++ installed When using native image compilation, you will also need:
GraalVm 22.3.0+ installed
Environment variable GRAALVM_HOME set accordingly
Note that GraalVM native image compilation typically requires other packages (glibc-devel, zlib-devel and gcc) to be installed too. You also need ‘native-image’ installed in GraalVM (using ‘gu install native-image’). Please refer to GraalVM installation documentation for more details.
minikube (https://minikube.sigs.k8s.io/docs/start/)
Knative quickstarts
Run eval $(minikube -p minikube docker-env --profile knative) to build the images in your internal Minikube registry.

Deploy the `custom-function-knative-service` project to Knative

From the custom-function-knative-service directory run:

mvn clean package -Dquarkus.kubernetes.deploy=true -Dquarkus.container-image.group=dev.local/<your_user>

Check if the service was successfully deployed:

kn service list

You should see something similar to (URL should change):

NAME                              URL                                                                      LATEST                                  AGE   CONDITIONS   READY   REASON
custom-function-knative-service   http://custom-function-knative-service.default.10.109.169.193.sslip.io   custom-function-knative-service-00001   13s   3 OK / 3     True

Deploy the `workflow` project to Knative

From the workflow directory run:

mvn clean package -Dquarkus.kubernetes.deploy=true -Dquarkus.container-image.group=dev.local/<your_user>

Check if the service was successfully deployed:

kn service list

You should see both services deployed similar to (URLs should change):

NAME                              URL                                                                      LATEST                                  AGE     CONDITIONS   READY   REASON
custom-function-knative-service   http://custom-function-knative-service.default.10.109.169.193.sslip.io   custom-function-knative-service-00001   3m53s   3 OK / 3     True    
workflow                          http://workflow.default.10.109.169.193.sslip.io                          workflow-00001                          12s     3 OK / 3     True

Submit a request with a plain JSON object

The service based on the JSON workflow definition can be accessed by sending a request to <URL>/plainJsonKnativeFunction (replace <URL> with the URL returned by the above command) with the following content:

{
  "name": "Kogito"
}

Complete curl command can be found below (replace <URL> with the URL for the workflow service returned by the kn service list command):

curl -X 'POST' \
  '<URL>/plainJsonKnativeFunction' \
  -H 'accept: */*' \
  -H 'Content-Type: application/json' \
  -d '{ "name": "Kogito" }'

Should return something like this (“id” will change):

{"id":"87cf8275-782d-4e0b-a9be-a95f95c9c190","workflowdata":{"name":"Kogito","greeting":"Greetings from Serverless Workflow, Kogito"}}

Submit a request with a CloudEvent

The service based on the JSON workflow definition can be accessed by sending a request to <URL>/cloudEventKnativeFunction (replace <URL> with the URL returned by the above command) with the following content:

{
  "cloudevent": {
    "specversion": "1.0",
    "source": "org.acme.source",
    "type": "test" 
  }
}

[NOTE]

Kogito Serverless Workflow generates a CloudEvent ID based on `source` and the workflow instance ID. In case an ID is set, Kogito Serverless Workflow will ignore it and use a generated one.