Scalable Containerized Machine Learning Model Serving with AWS ECS

Question

Pulumi · Accepted Answer

To serve a machine learning model on AWS using containerized services, you want to set up an infrastructure capable of running Docker containers with high availability and scalability. AWS Elastic Container Service (ECS) works well for this purpose, providing a managed service that can run your containers on a cluster of instances.

In this program, we will:
1. Create an ECS cluster to host our service.
2. Define a task definition with a Docker container specification to serve the machine learning model.
3. Configure a Fargate service using the task definition to abstract away the infrastructure management.
4. Ensure our service is scalable by specifying the desired count and configuring auto-scaling parameters.

Below is the Pulumi program in Python that accomplishes the above:

```python
import pulumi
import pulumi_aws as aws

# Create an ECS cluster where our services will run.
ecs_cluster = aws.ecs.Cluster("model-serving-cluster")

# Define an Elastic Container Registry (ECR) to store our machine learning model serving Docker images.
ecr_repository = aws.ecr.Repository("model-serving-repo")

# Here we are creating an ECS task definition. This is where you describe the Docker container
# that will be launched, including CPU and memory requirements, the Docker image to use,
# and the command the container should run on startup, among other configurations.
task_definition = aws.ecs.TaskDefinition("model-serving-task",
    family="model-serving",
    cpu="512",  # Adequate CPU for the model serving
    memory="2048",  # Memory required for the model serving
    network_mode="awsvpc",  # Use the VPC networking mode
    requires_compatibilities=["FARGATE"],  # Specify that this task definition is for Fargate
    execution_role_arn=pulumi_aws.iam.get_role(name="ecsTaskExecutionRole").arn,  # Execution role that allows Fargate to manage tasks
    container_definitions=pulumi.Output.all(ecr_repository.repository_url).apply(lambda url: f"""
    [
        {{
            "name": "model-serving-container",
            "image": "{url}:latest",
            "portMappings": [
                {{
                    "containerPort": 80,
                    "hostPort": 80
                }}
            ]
        }}
    ]
    """)
)

# Now, we create an ECS service that defines the scaling and networking configuration for our model serving.
# Fargate allows us to run containers without managing servers or clusters.
ecs_service = aws.ecs.Service("model-serving-service",
    cluster=ecs_cluster.id,
    desired_count=1, # Initially start with 1 task
    launch_type="FARGATE",
    task_definition=task_definition.arn,
    network_configuration=aws.ecs.ServiceNetworkConfigurationArgs(
        subnets=["subnet-XXXXXXXX", "subnet-YYYYYYYY"],  # Subnets for the task networking
        security_groups=["sg-XXXXXXXX"]  # Security group for the tasks
    ),
    load_balancers=[aws.ecs.ServiceLoadBalancerArgs(
        target_group_arn="arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-targets/1234567890123456",
        container_name="model-serving-container",
        container_port=80
    )]
)

# Export the ECS cluster name and the ECS service name
pulumi.export('ecs_cluster_name', ecs_cluster.name)
pulumi.export('ecs_service_name', ecs_service.name)
```

Let's break down the code above:

- **ECS Cluster**: An ECS cluster is a logical grouping of tasks or services. Here, `model-serving-cluster` provides the infrastructure to run our machine learning model serving workload.
- **ECR Repository**: Amazon Elastic Container Registry (ECR) is a Docker container registry for storing, managing, and deploying Docker container images. The `model-serving-repo` stores the image that will serve the model.
- **Task Definition**: The `model-serving-task` defines the Docker image to use (retrieved from our ECR repository), the necessary CPU and memory resources, and the networking mode. The definition also specifies that the container should use Fargate for task execution.
- **ECS Service**: The `model-serving-service` manages the deployment and scaling of the specified `task_definition`. It also ties our service to the specified load balancer to distribute traffic to the running containers.

Before deploying this code with Pulumi, replace the placeholder values (like the subnets, security groups, and target group ARN) with actual values from your AWS environment.

Lastly, this program sets up the foundation for model serving. Depending on requirements, further details would need to be fleshed out, such as the load balancer configuration, detailed container definitions, Auto Scaling policies, and other necessary services like a Redis cache or an Amazon SageMaker endpoint for the actual model inference.