azurefunctioneventgridevent

Azure Function Event Grid event Java example

This folder contains a Java application example that handles Functions on Microsoft Azure.

It handles an Azure Function that responds to an Event Grid event (trigger) when an event is sent to an Event Grid topic.

Requirements

• You must have a Microsoft Azure subscription.

• To develop functions app with Java, you must have the following installed:

  • Java Developer Kit, version 8.
  • Apache Maven, version 3.0 or above.
  • Azure CLI
  • Azure Functions Core Tools Version 3.x

• The code was written for:

  • Java 8
  • Apache Maven 3

• Azure Functions Core Tools Version 3.x

  Azure Functions Core Tools lets you develop and test your functions on your local computer from the command prompt or terminal. Your local functions can connect to live Azure services, and you can debug your functions on your local computer using the full Functions runtime. You can even deploy a function app to your Azure subscription.

  Version 3.x/2.x: Supports either version 3.x or 2.x of the Azure Functions runtime. These versions support Windows, macOS, and Linux and use platform-specific package managers or npm for installation.

  Azure Functions Core Tools currently depends on either the Azure CLI or Azure PowerShell for authenticating with your Azure account. This means that you must install one of these tools to be able to publish to Azure from Azure Functions Core Tools.

  Version 3.x/2.x of the tools uses the Azure Functions runtime that is built on .NET Core. This version is supported on all platforms .NET Core supports, including Windows, macOS, and Linux.

  Install version 3.x of the Core Tools on your local computer:

  • For Windows:

    1. Download and run the Core Tools installer, based on your version of Windows:

       • v3.x - Windows 64-bit (Recommended. Visual Studio Code debugging requires 64-bit.)
       • v3.x - Windows 32-bit

    2. If you don't plan to use extension bundles, install the .NET Core 3.x SDK for Windows.

  • For MacOS:

    1. Install Homebrew, if it's not already installed.

    2. Install the Core Tools package:

       brew tap azure/functions
       brew install azure-functions-core-tools@3
       # if upgrading on a machine that has 2.x installed
       brew link --overwrite azure-functions-core-tools@3

    3. If you don't plan to use extension bundles, install the .NET Core 3.x SDK for macOS.

Using the code

• Create the Azure Funtion project and the Azure Function (Boilerplate code).

  This step is only necessary when you want to create an Azure Function from scratch.

  The Azure Functions Core Tools help you to create the boilerplate code for the Azure Funtion project and the Azure Function using a Maven archetype

  In the terminal window or from a command prompt, navigate to an empty folder for your project, and run the following command:

  mvn archetype:generate "-DarchetypeGroupId=com.microsoft.azure" "-DarchetypeArtifactId=azure-functions-archetype" "-DjavaVersion=8" "-Dtrigger=EventGridTrigger"

  Maven asks you for values needed to finish generating the project on deployment. Provide the following values when prompted:

  • groupId: com.alfonsof.azureexamples
  • artifactId: azurefunctioneventgridevent
  • version: 1.0.0
  • package: example
  • trigger: EventGridTrigger

  Then, the project is created with azurefunctioneventgridevent and these files:

  • host.json - JSON configuration file.
  • local.settings.json - It stores app settings, connection strings, and settings used by local development tools. Settings in the local.settings.json file are used only when you're running projects locally.
  • pom.xml - Maven POM file.
  • The src/main/java/example folder content is:
    • Function.java - Code of the function.

  Because local.settings.json can contain secrets downloaded from Azure, the file is excluded from source control by default in the .gitignore file.

• Create an Event Grid Topic.

  An Event Grid topic provides a user-defined endpoint that you post your events to.

  You must create the Event Grid Topic, using the Azure console, do the following actions:

  1. Select Create a resource and chose Event Grid Topic.

  2. On the Event Grid Topics page, select Create.

  3. Choose the Subscription, Resource group, Name and Region for your Event Grid Topic.

  4. Select Create.

• Configure the Azure Function.

  1. You must configurate the pom.xml file for a proper creation of the Function App during the subsequent deployment process.

     Replace with the proper values in the pom.xml file:

     • <FUNCTION_APP> - Function App name.
     • <RESOURCE_GROUP> - Resource group name.
     • <APP_SERVICE_PLAN> - App Service Plan name.
     • <REGION>- Azure region name.
     • <os>linux</os> - It is for a Linux operating system.
     • <javaVersion>8</javaVersion> - It is for a runtime Java version 8.
     • <value>~3</value> - It is for functions version 3.

     Part of the pom.xml file:

     <configuration>
       <!-- function app name -->
       <appName><FUNCTION_APP></appName>
       <!-- function app resource group -->
       <resourceGroup><RESOURCE_GROUP></resourceGroup>
       <!-- function app service plan name -->
       <appServicePlanName><APP_SERVICE_PLAN></appServicePlanName>
       <!-- function app region-->
       <region><REGION></region>
       <runtime>
           <!-- runtime os, could be windows, linux or docker-->
           <os>linux</os>
           <javaVersion>8</javaVersion>
       </runtime>
       <appSettings>
           <property>
               <name>FUNCTIONS_EXTENSION_VERSION</name>
               <value>~3</value>
           </property>
       </appSettings>
     </configuration>

• Package the Azure Function.

  Package your code into a new Function app using the package Maven target.

  mvn clean package

• Deploy the Azure Function to Azure & Create the Function App

  The deploy process to Azure Functions uses account credentials from the Azure CLI. Log in with the Azure CLI before continuing.

  az login

  Deploy your code into a new Function app using the azure-functions:deploy Maven target.

  mvn azure-functions:deploy

  This creates the Function App using the configuration in the pom.xml file, and the Storage Account that Function App needs. In addition, the function is deployed to the Function App.

  When the deploy is complete, you will see the message:

  [INFO] ------------------------------------------------------------------------
  [INFO] BUILD SUCCESS
  [INFO] ------------------------------------------------------------------------
  [INFO] Total time:  02:03 min
  [INFO] Finished at: 2021-10-11T16:07:38+02:00
  [INFO] ------------------------------------------------------------------------

• Subscribe to an Event Subscription.

  You subscribe to an event grid topic to tell Event Grid which events you want to track, and where to send the events.

  You must subscribe to custom topic by creating an Event Subscription, using the Azure console, do the following actions:

  1. Go to your Event Grid Topic resource.

  2. Select + Event Subscription.

  3. Enter a Name for the event subscription.

  4. Select Azure Function for the Endpoint Type.

  5. Choose Select an endpoint.

  6. For the function endpoint, select the Azure Subscription and Resource group your Function App is in and then select the Function App and Function you created earlier. Select Confirm Selection.

  7. Select Create.

• Test the function.

  You must send an event to your topic.

  In the Azure portal, select Cloud Shell. You use the Azure CLI and the curl command:

  1. Select Bash in the top-left corner of the Cloud Shell window.

  2. Run the following command to get the endpoint for the topic: After you copy and paste the command, update the <TOPIC_NAME> and <RESOURCE_GROUP_NAME> before you run the command.

     endpoint=$(az eventgrid topic show --name <TOPIC_NAME> -g <RESOURCE_GROUP_NAME> --query "endpoint" --output tsv)

  3. Run the following command to get the key for the custom topic: After you copy and paste the command, update the <TOPIC_NAME> and <RESOURCE_GROUP_NAME> before you run the command.

     key=$(az eventgrid topic key list --name <TOPIC_NAME> -g <RESOURCE_GROUP_NAME> --query "key1" --output tsv)

  4. Copy the following statement with the event definition, and press ENTER.

     event='[ {"id": "'"$RANDOM"'", "eventType": "recordInserted", "subject": "myapp/vehicles/motocycles", "eventTime": "'`date +%Y-%m-%dT%H:%M:%S%z`'", "data":{ "make": "Ducati", "model": "Monster"},"dataVersion": "1.0"} ]'

  5. Run the following curl command to post the event:

     curl -X POST -H "aeg-sas-key: $key" -d "$event" $endpoint

  You should see the next message in the log:

  Java Event Grid trigger function executed.
  {"id":"<EVENT_ID>","eventType":"recordInserted","subject":"myapp/vehicles/motocycles","data":{"make":"Ducati","model":"Monster"},"dataVersion":"1.0","metadataVersion":"1","eventTime":"2021-10-11T14:19:22+00:00","topic":"/subscriptions/09bcb799-9330-48ee-a63e-fb49b23bb6fa/resourceGroups/<RESOURCE_GROUP_NAME>/providers/Microsoft.EventGrid/topics/<EVENT_GRID_TOPIC>"}