Rate-Limiting AI API Calls with Azure API Management

Question

Pulumi · Accepted Answer

Rate limiting is an important aspect of API management as it helps to control the traffic to a web service, ensuring that the service remains reliable and available to all users. In Microsoft Azure, you can implement rate limiting using Azure API Management (APIM), a service that allows you to create consistent and modern API gateways for existing backend services.

In the context of Azure API Management, rate limiting is typically achieved by configuring policies. These policies are rules that you can apply to incoming API calls. You can set them on different scopes such as a product, API, or operation.

Here's a breakdown of how you might implement rate limiting for AI API calls using Pulumi with the azure-native provider package.

Create an API Management Service: This is the primary resource that represents the API management instance, where you'll configure APIs, products, and other settings.
Add an API: Represents the AI API which you want to rate limit. This requires you to define the service in terms of operations, parameters, and responses.
Configure a Product: Products in APIM are how you make APIs available to developers. A product can have one or more APIs and you can apply policies at the product level to enforce rate limits across all APIs in that product.
Apply Rate Limit Policy: You can define a policy to enforce rate limits. For example, you can limit the number of calls an API consumer can make within a time period, like 100 calls per minute.

Below is a Pulumi program written in Python that sets up an Azure API Management instance, configures an API (representing the AI API you'd like to rate limit), creates a product, and applies a rate limiting policy to it:

import pulumi
from pulumi_azure_native import apimanagement as apim

# Define the resource group to which the API Management service belongs.
resource_group = apim.ResourceGroup("resource_group", resource_group_name="my-resource-group")

# Create an API Management service instance.
api_management_service = apim.ApiManagementService("api_management_service",
    resource_group_name=resource_group.name,
    service_name="my-apim-instance",
    publisher_name="my-publisher",
    publisher_email="contact@example.com",
)

# Define an API that will be managed by the API Management service.
api = apim.Api("my_api",
    resource_group_name=resource_group.name,
    service_name=api_management_service.name,
    display_name="AI API",
    path="ai-api",
    protocols=["https"], # Use HTTPS protocol for security.
)

# Define a product which includes the AI API.
product = apim.Product("my_product",
    resource_group_name=resource_group.name,
    service_name=api_management_service.name,
    display_name="AI Product",
    description="Product for AI service rate limiting.",
    approval_required=False, # No approval required for subscription to this product.
    subscriptions_limit=1, # Limit the number of subscriptions one can have to this product.
    subscription_required=True, # Require subscription for accessing the APIs.
)

# Add API to the product.
product_api = apim.ProductApi("product_api",
    resource_group_name=resource_group.name,
    service_name=api_management_service.name,
    api_id=api.id,
    product_id=product.product_id,
)

# Rate limiting policy definition using XML policy language of Azure API Management.
rate_limit_policy_xml = """<policies>
    <inbound>
        <rate-limit calls="100" renewal-period="60"/>
        <!-- This policy allows 100 calls per minute -->
    </inbound>
    <backend>
        <forward-request />
    </backend>
    <outbound/>
</policies>"""

# Add a rate limiting policy at the product scope.
product_policy = apim.Policy("product_policy",
    resource_group_name=resource_group.name,
    service_name=api_management_service.name,
    policy_id="policy",
    content_type="application/vnd.ms-azure-apim.policy+xml",
    value=rate_limit_policy_xml,
)

pulumi.export("api_management_service_name", api_management_service.name)

This program sets up the Azure API Management service and applies rate limiting to an API. The rate-limit policy is defined within the Policy resource and applied to the product scope, which includes the defined AI API. This ensures that any call made to the AI API within this product will be subject to the rate limits specified by the policy.

You can adjust the calls and renewal-period attributes to control the rate limit as required for your scenarios. Keep in mind that the values used here, "100" and "60", can be modified to fit the rate at which you want to rate-limit the calls (100 calls per 60 seconds in this example).

The pulumi.export instruction at the end of the program outputs the name of the API Management service, which can be useful for external references or dependencies.

""" # Add a rate limiting policy at the product scope. product_policy = apim.Policy("product_policy", resource_group_name=resource_group.name, service_name=api_management_service.name, policy_id="policy", content_type="application/vnd.ms-azure-apim.policy+xml", value=rate_limit_policy_xml, ) pulumi.export("api_management_service_name", api_management_service.name) ``` This program sets up the Azure API Management service and applies rate limiting to an API. The `rate-limit` policy is defined within the `Policy` resource and applied to the product scope, which includes the defined AI API. This ensures that any call made to the AI API within this product will be subject to the rate limits specified by the policy. You can adjust the `calls` and `renewal-period` attributes to control the rate limit as required for your scenarios. Keep in mind that the values used here, "100" and "60", can be modified to fit the rate at which you want to rate-limit the calls (100 calls per 60 seconds in this example). The `pulumi.export` instruction at the end of the program outputs the name of the API Management service, which can be useful for external references or dependencies.