Horizontal Scaling of AI Services with Azure Container Instances

Question

Pulumi · Accepted Answer

Horizontal scaling is the process of adding or removing instances of a service to handle the load effectively. It enables a service to handle more requests by distributing the workload across multiple instances. For AI services, horizontal scaling can be essential to process large volumes of data or to serve a high number of requests concurrently.

Azure Container Instances (ACI) is a service that allows you to run containers in the Azure cloud without having to manage the underlying VMs. ACI is suitable for applications that require rapid elasticity, and it's perfect for horizontal scaling scenarios. With ACI, you can easily deploy additional container instances to handle increased load and remove them when they are no longer needed, paying only for what you use.

In a Pulumi program, you can describe your Azure infrastructure as code, including setting up Azure Container Instances for horizontal scaling. The following program demonstrates how to create a container group in Azure with a specific number of instances, which could house your AI services:

- `azure_native.containerinstance.ContainerGroup`: This resource allows us to create and manage a group of containers in ACI, including their networking, volumes, and instances.

Remember that Pulumi communicates with Azure through a service principal. Ensure that the Pulumi CLI is configured with credentials that have the appropriate permissions to create and manage these resources.

Here's the program that sets up a container group:

```python
import pulumi
import pulumi_azure_native as azure_native

# Create an Azure Resource Group
resource_group = azure_native.resources.ResourceGroup("aiResourceGroup")

# Define the container image for AI services
container_image = "your-ai-service-image"  # Replace this with your actual AI service image

# Specify the container port and CPU/Memory resources
container_port = 80  # The port that your AI service listens on
container_cpu = 1.0  # CPU cores per container
container_memory = 1.5  # GB of memory per container

# Define the container group with a specific number of container instances
container_group = azure_native.containerinstance.ContainerGroup("aiContainerGroup",
    resource_group_name=resource_group.name,
    os_type="Linux",
    containers=[{
        "name": "ai-service-container",
        "image": container_image,
        "resources": {
            "requests": {
                "cpu": container_cpu,
                "memory_in_gb": container_memory
            }
        },
        "ports": [{"port": container_port}],
    }],
    location=resource_group.location,
    ip_address={
        "ports": [{"port": container_port, "protocol": "TCP"}],
        "type": "Public",
    },
    # You can define auto-scaling rules here based on metrics (CPU usage, memory). This involves
    # advanced configurations and potentially additional resources like azure-native.monitor for metrics.
)

# Export the IP address of the container group
pulumi.export("container_ip", container_group.ip_address.apply(lambda ip: ip.ip if ip else 'Not Assigned'))
```

### What the Program Does:
- It sets up a new Azure Resource group named `aiResourceGroup`.
- It defines a single container with the necessary CPU and memory requirements to run your AI service.
- It creates a Public IP address and maps the port that your AI service listens on.
- It assumes that the image for your AI service is available in a public registry or Azure Container Registry (ACR). If it's in ACR or another private registry, you will need to provide image registry credentials.

### Before Running the Program:
- Replace `"your-ai-service-image"` with the actual image name for your AI services.
- If your services require specific environment variables or other configuration, you should add those to the container definition.
- Monitor autoscaling because the provided code does not include autoscaling logic. 
  
### To Deploy This Infrastructure:
1. Install the Pulumi CLI.
2. Configure authentication to Azure with the Pulumi CLI.
3. Create a new directory, and inside the directory, set up a new Pulumi project using `pulumi new azure-python`.
4. Replace the generated code in `__main__.py` with the code block above.
5. Run `pulumi up` to preview and deploy the changes.

### After Running the Program:
- Check the outputs from the Pulumi CLI to find the IP address assigned to your AI services.
- Verify that the container instances are running as expected in the Azure portal and that they are properly load balancing the requests for your AI service.

This code is the foundation for a horizontally-scalable AI service using Azure Container Instances. From here, you can enhance the system with auto-scaling, proper logging, monitoring, and other Azure services to support your AI application.