Info: Azure Functions can be written in Ballerina using the listeners and services provided by the Azure Functions package.

Supported triggers and bindings

An Azure Function consists of a trigger and optional bindings. A trigger defines how a function is invoked. A binding is an approach in which you can declaratively connect other resources to the function.

There are input and output bindings. An input binding is a source of data that flows into the function. An output binding allows outputting data from the function to an external resource. For more information, go to Azure Functions triggers and bindings concepts.

The following Azure Functions triggers and bindings are currently supported in Ballerina.

Set up the prerequisites

Follow the instructions in the sections below to set up the prerequisites.

Set up Azure Functions

Follow the steps below to set up the Azure Functions.

1. Create an Azure subscription.
2. Install the Azure CLI.
3. Install and configure the Functions Core Tools.

Create the app

Follow the steps below to create the Azure function app.

Note: Make sure to remember the function application name and storage account name as they will be required in the code samples.

1. Execute the az login command on the CLI to log in to the Azure CLI.

2. Create an Azure Function app with the default option of creating a resource group automatically and the requirements below.

   • Runtime stack - Java 17
   • Hosting operating system - Windows (Currently, Linux is not supported in Azure by default for custom handlers.)

Create the function

You can write Azure functions that use different triggers to invoke the function, and output bindings to generate the response based on your use case.

Info: For examples of creating Azure functions, see Examples.

Build the function

The Azure Functions functionality is implemented as a compiler extension. Therefore, artifact generation happens automatically when you build a Ballerina module by executing the command below.

$ bal build --cloud="azure_functions"

Deploy the function

To deploy the function, execute the command, which you get in the CLI output logs after you build the function. For examples, see Examples.

Note: When you are deploying, make sure to replace the <function_app_name> placeholder with the app name of the created function.

Azure Functions as a native executable

You can use Azure Functions in the native approach of Ballerina.

Set up the prerequisites

Follow the steps below to set up the prerequisites, which are specifically required to follow the native approach.

1. Set up the general prerequisites.
2. Install and configure Docker in your machine.
3. Install and configure GraalVM in your machine.

Create the app

Create an Azure Function app with the given resource group with the following requirements.

• Runtime stack - Java 17
• Hosting operating system - Linux (As of now, Ballerina Azure functions native support is only available for Linux.)

Create the function

An Azure Functions package supports the two build options below.

Info: Both build options for the non-native JVM-based approach will behave the same since the JVM is platform-independent.

• cloud="azure_functions" - Builds the native executable to be compatible with the Azure Functions cloud.
• cloud="azure_functions_local" - Builds the native executable to be compatible with your machine for development purposes.

You can use these build options along with the graalvm build option (--graalvm) while building the package, as shown below.

Build locally

The example command below will build the package and run it locally.

$ bal build --cloud="azure_functions_local" --graalvm

Info: This will use the GraalVM you installed on your machine to build the native image and make the generated executable compatible with your machine.

Build for the cloud

The example command below will build the package for the Azure Functions cloud.

$ bal build --cloud="azure_functions" --graalvm

Info: This will perform the compilation inside the Docker image to make it compatible with the Azure Functions cloud environment.

Deploy the function

You can either deploy the Azure Functions package locally or on the Azure Functions cloud.

Deploy locally

The example command below will deploy the package locally.

$ func start --script-root target/azure_functions

Deploy on the cloud

The example command below will deploy the package on the Azure Functions cloud.

$ func azure functionapp publish <function_app_name> --script-root target/azure_functions

Examples

For examples of the usage of Azure Functions, see Azure Functions.