Assigning Public IPs to Azure Functions for AI Event Processing

Question

Pulumi · Accepted Answer

Assigning a public IP address to an Azure Functions instance involves several steps, as Azure Functions typically run within an Azure-managed infrastructure that does not expose individual functions with a public IP by default. However, you can achieve this by using an Azure Application Gateway or Azure API Management to provide a dedicated endpoint with a public IP that routes to your Azure Functions.

In this case, we will create an Azure Function App, provision a public IP address, and set up an Azure Application Gateway to route traffic to the Azure Function App. Note that we have to use an App Service Plan that supports VNET integration for the Function App to integrate with the Application Gateway.

We start by setting up the Function App using the `azure.appservice.FunctionApp` resource. The next step is to set up a public IP using the `azure_native.network.PublicIPAddress` resource. Lastly, we create an Application Gateway using the `azure_native.network.ApplicationGateway` resource with a front-end IP configuration that points to the assigned public IP and a backend pool that includes the Function App.

Let's go through the actual Pulumi program in Python that accomplishes this.

```python
import pulumi
import pulumi_azure as azure
import pulumi_azure_native as azure_native

# First, create the Azure Resource Group
resource_group = azure_native.resources.ResourceGroup("ai_event_processing_rg")

# Create an Azure Function App
app_service_plan = azure.appservice.Plan("ai_event_processing_plan",
    resource_group_name=resource_group.name,
    kind="FunctionApp",
    sku=azure.appservice.PlanSkuArgs(
        tier="Dynamic",
        size="Y1",
    ),
)

storage_account = azure.storage.Account("aieventstorage",
    resource_group_name=resource_group.name,
    account_tier="Standard",
    account_replication_type="LRS",
)

function_app = azure.appservice.FunctionApp("ai_event_processor",
    resource_group_name=resource_group.name,
    app_service_plan_id=app_service_plan.id,
    storage_account_name=storage_account.name,
    storage_account_access_key=storage_account.primary_access_key,
    os_type="linux",
)

# Allocate a public IP address
public_ip = azure_native.network.PublicIPAddress("ai_event_processor_ip",
    resource_group_name=resource_group.name,
    location=resource_group.location,
    public_ip_allocation_method=azure_native.network.IPAllocationMethod.DYNAMIC,
)

# Now setup an Application Gateway to route traffic to the Azure Function App
# Assuming the Function App is exposed on a certain port (e.g., 80) via an internal load balancer
app_gateway = azure_native.network.ApplicationGateway("ai_event_application_gateway",
    resource_group_name=resource_group.name,
    location=resource_group.location,
    sku=azure_native.network.ApplicationGatewaySkuArgs(
        name=azure_native.network.ApplicationGatewaySkuName.STANDARD_V2,
        tier=azure_native.network.ApplicationGatewayTier.STANDARD_V2,
    ),
    gateway_ip_configurations=[
        azure_native.network.ApplicationGatewayIPConfigurationArgs(
            name="appGatewayIpConfig",
            subnet=azure_native.network.SubResourceArgs(
                id=function_app.outbound_ip_addresses.apply(
                    lambda ips: ips.split(",")[0]  # Take first outbound IP for the subnet config
                )
            ),
        )
    ],
    frontend_ip_configurations=[
        azure_native.network.ApplicationGatewayFrontendIPConfigurationArgs(
            name="appGatewayFrontendIp",
            public_ip_address=azure_native.network.SubResourceArgs(
                id=public_ip.id,
            ),
        )
    ],
    # Configure other required settings like listeners, routing rules etc. for the Application Gateway
)

# Export the Function App URL and the public IP to access it
pulumi.export("function_app_hostname", function_app.default_hostname)
pulumi.export("public_ip", public_ip.ip_address)
```

This program sets up the necessary infrastructure to publicly expose an Azure Function App:

1. It defines an Azure Resource Group that provides a logical grouping for the resources we are about to create.
2. It sets up an App Service Plan which determines the location and capabilities of the function app.
3. We create a Storage Account required for the function app to manage state and other dynamic data.
4. The Function App itself is declared, where your AI processing logic would live.
5. A Dynamic Public IP resource is created that we will associate with our Application Gateway.
6. The Application Gateway is created with the necessary configuration pointing to the Function App, enabling public access via the Public IP.

Remember to replace `tier` and `size` for `AppService.Plan` and any other required values with ones that align with your specific requirements and resources.

After this program is run with Pulumi, your function will be publicly accessible via the allocated public IP. The URL of the function and the IP will be outputted by Pulumi, which you can then use in your application or DNS configuration as necessary.