Creating and Testing Serverless Functions

Business Scenario

You are a developer and must create an API to receive and process data. You have heard of the approach to use Serverless Functions to implement such an API. Furthermore, you want to learn how to create a Serverless Function and how to use it.

Note

We strongly recommend first performing the steps in the live environment.

Live Environment

In this exercise, you will perform the following steps:

Create a Serverless Function using kubectl.
Create a Serverless Function using the Kyma dashboard.
Expose and test the Function using HTTP.

Prerequisites

You have successfully created a SAP BTP, Kyma runtime instance in the SAP BTP subaccount.
You have added the Serverless module. See Adding Kyma Modules.
You have configured kubectl to work with your SAP BTP, Kyma runtime instance.

Task 1: Create and Test a Serverless Function

Steps

Create a Serverless Function using kubectl.
1. Open your terminal and list all current Serverless Functions in your default namespace:
  Code Snippet
```
1
kubectl get functions
```
  If your namespace has no Functions, you get an empty list.
2. Create a Serverless Function using the following command:
  Code Snippet
```
1
kubectl apply -n default -f https://raw.githubusercontent.com/sap-samples/kyma-runtime-learning-journey/main/unit_3/functions/hello-world-function.yaml
```
  If successful, you get the output: function.serverless.kyma-project.io/hello-world-function created.
3. List all Serverless Functions in your namespace again:
  Code Snippet
```
1
kubectl get functions
```
  The Function hello-world-function is on the list.
Create a Serverless Function using Kyma dashboard.
Use the following data:
Field Value
Name hello-kyma-function
Runtime use the latest supported version
Source Inline editor
1. Open Kyma dashboard, go to Namespaces, and choose default.
2. Go to Workloads → Functions and choose Create.
  The Create Function view opens.
3. Enter the following information:
  - Name: hello-kyma-function
  - Language: JavaScript
  You can also check the YAML tab to see, copy, or edit the YAML manifest of the Function.
4. Choose the Create button.
  Your function is now being created. After a few seconds, it has the status Running.
Expose and test the Function using HTTP.
Note
We expose the Function using HTTP so that we can test it in a browser. You will find out more about exposure later in the course.
Use the following data:
Field Value
Name hello-kyma-function-api
Service hello-kyma-function (port: 80)
1. Navigate to Discovery and Network → API Rules and choose Create.
2. Enter the following information and choose the Create button:
  - Name: hello-kyma-function-api
  - Service Name: hello-kyma-function
  - Choose the host of your Kyma cluster, and replace the * wildcard character with the subdomain hello-kyma-function .
  - Access Strategy: No Auth
  This will expose your function as an HTTP endpoint. Only GET requests are allowed.
3. Paste the URL hello-kyma-function.<your-domain> in your browser.
4. You get the following message:
  Hello world from the Kyma Function hello-kyma-function running on nodejs20!

Field	Value
Name	hello-kyma-function
Runtime	use the latest supported version
Source	Inline editor

Field	Value
Name	hello-kyma-function-api
Service	hello-kyma-function (port: 80)

Result

Bravo, you have successfully created and tested a Serverless Function!