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Trigger a Microservice with an Event

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Trigger a Microservice with an Event
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Trigger a Microservice with an Event

October 8, 2020
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October 8, 2020
Trigger a microservice to run when an event is published into the Kyma runtime.

You will learn

  • How to trigger a microservice with an event


Step 1: Clone the Git repository
  1. Copy the repository URL.

In your browser, navigate to kyma-runtime-extension-samples

Choose the Code button and choose one of the options to download the code locally or simply run the following command within your CLI at your desired folder location.

```Shell/Bash
git clone https://github.com/SAP-samples/kyma-runtime-extension-samples
```
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Step 2: Explore the sample
  1. Open the directory api-mssql-go in your desired editor.

  2. Explore the content of the sample.

  3. Within the file internal/api/events.go you will find the code that handles the consumption of the event data. This code expects to receive a json payload containing an orderCode. This function is exposed on the path /orderCodeEvent, which is defined in cmd/api/main.go.

  4. Within the k8s directory you will find the Trigger which defines how an event will be consumed. The fields of interest included:

Property Description Value
spec.filter.attributes.eventtypeversion The event version to subscribe to v1
spec.filter.attributes.source the name of the Application that publishes the events mp-commerce-mock
spec.filter.attributes.type The event type to subscribe to order.created
spec.filter.subscriber.ref.name The name of the service to receive the event api-mssql-go
spec.filter.subscriber.uri The URI endpoint of the service that should receive the event /orderCodeEvent
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Step 3: Bind commerce mock to namespace

In this step we will bind the mock application to the dev namespace. This process is used to enable the usage of the APIs and events of the mock application to the bounded namespace. The API and events will then appear within the Service Catalog of the namespace.

  1. Open the Kyma runtime console.

  2. Choose the menu option Integration > Applications/Systems.

  3. Choose mp-commerce-mock.

  4. Choose Create Binding.

  5. Choose the namespace dev.

  6. Choose Create

    Binding
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Step 4: Create service instance

In this step we will create a service instance of the events exposed by the mock application. This is done to enabled the consumption of the events within the dev namespace.

  1. Open the Kyma runtime console

  2. Choose the namespace dev.

  3. Choose the menu option Service Management > Catalog.

  4. Choose mp-commerce-mock.

    Service Instance
  5. Choose the Service Class Plan SAP Commerce Cloud - Events.

    Service Instance Plan
  6. Choose Add.

    Service Instance Plan
  7. Choose Create to create an instance.

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Step 5: Apply trigger

In this step we will define a trigger which is used to create a subscriber of an event. This will allow use to specify that our API application api-mssql-go, by referencing it’s service, should receive the payload of the event order.created.

  1. Apply the Trigger by running the following command in the Command Line Interface.

    kubectl -n dev apply -f ./k8s/event-trigger.yaml
    
  2. Verify that the trigger was created successfully by running the command:

    kubectl get trigger api-mssql-go-trigger -n dev -o yaml
    

    After the trigger definition you should find a status object indicating the status of the related resources.

    status:
      conditions:
      - lastTransitionTime: "2020-10-07T16:09:44Z"
        status: "True"
        type: BrokerReady
      - lastTransitionTime: "2020-10-07T16:09:26Z"
        status: "True"
        type: DependencyReady
      - lastTransitionTime: "2020-10-07T16:09:44Z"
        status: "True"
        type: Ready
      - lastTransitionTime: "2020-10-07T16:09:27Z"
        status: "True"
        type: Subscribed
      - lastTransitionTime: "2020-10-07T16:09:26Z"
        status: "True"
        type: SubscriberResolved
    
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Step 6: Test scenario

With the configuration steps completed, we can now test the scenario to validate that it is working as intended.

  1. Open the mock application in the browser by first choosing the menu option Configuration > APIRules.

  2. Choose the Host entry for the commerce-mock APIRule to open it in the browser. This URL should be similar to https://commerce.*******.kyma.shoot.live.k8s-hana.ondemand.com.

  3. Choose the Remote APIS tab.

    Test the Scenario
  4. Choose the SAP Commerce Cloud - Events option.

  5. For the Event Topics choose order.created.v1.

  6. Modify the orderCode value is desired and choose **Send Event

    Test the Scenario
  7. With the Kyma console choose the menu option Configuration > APIRules.

  8. Choose the Host entry for the fe-ui5-mssql APIRule to open the application in the browser. This should be similar to https://fe-ui5-mssql.*******.kyma.shoot.live.k8s-hana.ondemand.com.

  9. You should now see the data received by the event as shown below.

    Test the Scenario
What property of a Trigger definition is used to specify the application which publishes the events?
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