Getting Started

We are going to set up a sensor and event-source for webhook. The goal is to trigger an Argo workflow upon an HTTP Post request.

Note: You will need to have Argo Workflows installed to make this work. The Argo Workflow controller will need to be configured to listen for Workflow objects created in argo-events namespace. (See this link.) The Workflow Controller will need to be installed either in a cluster-scope configuration (i.e. no "--namespaced" argument) so that it has visiblity to all namespaces, or with "--managed-namespace" set to define "argo-events" as a namespace it has visibility to. To deploy Argo Workflows with a cluster-scope configuration you can use this installation yaml file, setting ARGO_WORKFLOWS_VERSION with your desired version. A list of versions can be found by viewing these project tags in the Argo Workflow GitHub repository.

    export ARGO_WORKFLOWS_VERSION=3.5.4
    kubectl create namespace argo
    kubectl apply -n argo -f https://github.com/argoproj/argo-workflows/releases/download/v$ARGO_WORKFLOWS_VERSION/install.yaml

1. Install Argo Events

   kubectl create namespace argo-events
   kubectl apply -f https://raw.githubusercontent.com/argoproj/argo-events/stable/manifests/install.yaml
   # Install with a validating admission controller
   kubectl apply -f https://raw.githubusercontent.com/argoproj/argo-events/stable/manifests/install-validating-webhook.yaml
   

2. Make sure to have the eventbus pods running in the namespace. Run following command to create the eventbus.

   kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/stable/examples/eventbus/native.yaml
   

3. Setup event-source for webhook as follows.

   kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/stable/examples/event-sources/webhook.yaml
   

The above event-source contains a single event configuration that runs an HTTP server on port 12000 with endpoint example.

After running the above command, the event-source controller will create a pod and service.

1. Create a service account with RBAC settings to allow the sensor to trigger workflows, and allow workflows to function.

    # sensor rbac
   kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/master/examples/rbac/sensor-rbac.yaml
    # workflow rbac
   kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/master/examples/rbac/workflow-rbac.yaml
   

2. Create webhook sensor.

   kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/stable/examples/sensors/webhook.yaml
   

Once the sensor object is created, sensor controller will create corresponding pod and a service.

1. Expose the event-source pod via Ingress, OpenShift Route or port forward to consume requests over HTTP.

   kubectl -n argo-events port-forward $(kubectl -n argo-events get pod -l eventsource-name=webhook -o name) 12000:12000 &
   

2. Use either Curl or Postman to send a post request to the http://localhost:12000/example.

   curl -d '{"message":"this is my first webhook"}' -H "Content-Type: application/json" -X POST http://localhost:12000/example
   

3. Verify that an Argo workflow was triggered.

   kubectl -n argo-events get workflows | grep "webhook"