Introduction¶

In the tutorials, we will cover every aspect of Argo Events and demonstrate how you can leverage these features to build an event driven workflow pipeline. All the concepts you will learn in this tutorial and subsequent ones can be applied to any type of event-source.

Prerequisites¶

Follow the installation guide to set up the Argo Events.
Make sure to configure Argo Workflow controller to listen to 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 visibility 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:
```
kubectl apply -n argo -f https://github.com/argoproj/argo-workflows/releases/latest/download/install.yaml
```
Make sure to read the concepts behind eventbus. sensor. event source.
Follow the instruction to create a Service Account operate-workflow-sa with proper privileges, and make sure the Service Account used by Workflows (here we use default in the tutorials for demonstration purpose) has proper RBAC settings.

Get 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.

Let' set up the eventbus.

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

Create the webhook event source.

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

Create the webhook sensor.

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

If the commands are executed successfully, the eventbus, event-source and sensor pods will get created. You will also notice that a service is created for the event-source.

Expose the event-source pod via Ingress, OpenShift Route or port forward to consume requests over HTTP.
```
kubectl -n argo-events port-forward <event-source-pod-name> 12000:12000
```

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

Now, you should see an Argo workflow being created.
```
kubectl -n argo-events get wf
```
Make sure the workflow pod ran successfully.
```
argo logs -n argo-events @latest
```

Should result in something similar to what is below.

    _________________________________________
    / {"context":{"type":"webhook","specVersi \
    | on":"0.3","source":"webhook","e |
    | ventID":"38376665363064642d343336352d34 |
    | 3035372d393766662d366234326130656232343 |
    | 337","time":"2020-01-11T16:55:42.996636 |
    | Z","dataContentType":"application/json" |
    | ,"subject":"example"},"data":"eyJoZWFkZ |
    | XIiOnsiQWNjZXB0IjpbIiovKiJdLCJDb250ZW50 |
    | LUxlbmd0aCI6WyIzOCJdLCJDb250ZW50LVR5cGU |
    | iOlsiYXBwbGljYXRpb24vanNvbiJdLCJVc2VyLU |
    | FnZW50IjpbImN1cmwvNy41NC4wIl19LCJib2R5I |
    | jp7Im1lc3NhZ2UiOiJ0aGlzIGlzIG15IGZpcnN0 |
    \ IHdlYmhvb2sifX0="}                      /
     -----------------------------------------
        \
         \
          \
                        ##        .
                  ## ## ##       ==
               ## ## ## ##      ===
           /""""""""""""""""___/ ===
      ~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ /  ===- ~~~
           \______ o          __/
            \    \        __/
              \____\______/

Note: You will see the message printed in the workflow logs contains both the event context and data, with data being base64 encoded. In later sections, we will see how to extract particular key-value from event context or data and pass it to the workflow as arguments.

Troubleshoot¶

If you don't see the event-source and sensor pod in argo-events namespace,

Inspect the event-source.

kubectl -n argo-events get eventsource event-source-object-name -o yaml

Inspect the sensor.

kubectl -n argo-events get sensor sensor-object-name -o yaml

and look for any errors within the Status.

Make sure the correct Role and RoleBindings are applied to the service account and there are no errors in both event-source and sensor controller.
Check the logs of event-source and sensor controller. Make sure the controllers have processed the event-source and sensor objects and there are no errors.
Raise an issue on GitHub or post a question on argo-events slack channel.