Cost-Effective AI Batch Processing with KEDA on Kubernetes

Question

Pulumi · Accepted Answer

Batch processing is a common pattern in systems that process large volumes of data. It involves running a job to completion, often on a schedule, to perform an operation like transforming data or making bulk updates to a database. Kubernetes is an excellent platform for batch processing because it can efficiently schedule these jobs and manage the resources they consume.

When constructing cost-effective AI batch processing on Kubernetes, it's essential to think about the scaling capabilities of your jobs, as the amount of data they need to process can vary greatly. Kubernetes Event-driven Autoscaling (KEDA) is a component that can automatically scale your Kubernetes Jobs. KEDA works by activating and deactivating Kubernetes Jobs to match the load of your processing needs without manual intervention, ensuring that you're only using resources when necessary.

In this demonstration, we'll set up a Kubernetes Job for batch processing and utilize KEDA to enable automatic scaling. The autoscaling will be based on arbitrary criteria such as the number of items in a queue or the results of a metrics query. For this example, we're going to demonstrate how you might set up a basic Kubernetes Job for batch processing without integrating KEDA, as including KEDA would require additional context about the specific workload and monitoring setup. However, the concept and code provided will be a solid foundation for you to build upon and integrate KEDA into your batch processing on Kubernetes.

Below is a Pulumi Python program that declares a `Job` in Kubernetes to perform batch processing.

```python
import pulumi
import pulumi_kubernetes as k8s

# Define the container image to use for the batch job
container_image = "your-docker-image-for-batch-processing"

# Define the batch job
batch_job = k8s.batch.v1.Job(
    "batch-job",
    spec=k8s.batch.v1.JobSpecArgs(
        template=k8s.core.v1.PodTemplateSpecArgs(
            spec=k8s.core.v1.PodSpecArgs(
                containers=[k8s.core.v1.ContainerArgs(
                    name="batch-container",
                    image=container_image
                )],
                restart_policy="Never",  # Ensure the Job does not restart automatically
            ),
        ),
        backoff_limit=2,  # Specify the number of times a Job will try to restart upon failure
    ),
    metadata=k8s.meta.v1.ObjectMetaArgs(
        name="batch-job",
        labels={"purpose": "batch-processing"},
    )
)

# Export the batch job name
pulumi.export('batch_job_name', batch_job.metadata["name"])
```

This Pulumi program creates a Kubernetes Job that uses a specified Docker image to perform a batch processing task. The `restart_policy` is set to "Never" so that if the job fails, it will not automatically restart, which is a standard setup for batch jobs. The `backoff_limit` is set to 2, which specifies how many times Kubernetes will retry the job if it fails.

To them implement KEDA for automatic scaling with this job, the exact setup would depend on the specific triggers you want to use (e.g., queue length, CPU/memory usage, etc.). KEDA would integrate with external systems like message queues or database queries to determine when to scale the jobs.

Once you have your specific scaling requirements, you would then configure KEDA ScaledObjects to specify how your batch jobs should scale. You would refer to [KEDA documentation](https://keda.sh/docs/2.5/concepts/scaling-jobs/) and the specific metrics or system you're using as a scale trigger.

Do note, since KEDA is an application-specific setup, it would involve understanding the triggers (queues, databases, etc.), and setting up proper Role-Based Access Control (RBAC) permissions for KEDA to monitor these triggers.

Here are the key steps to implementing KEDA on Kubernetes for AI batch processing jobs:

1. Install KEDA into your Kubernetes cluster. See the [KEDA installation guide](https://keda.sh/docs/2.5/deploy/).
2. Define a ScaledObject resource in your Pulumi program that configures KEDA to respond to external events.
3. Ensure that your Kubernetes cluster has access to the necessary resources (like a message queue or database) that KEDA will monitor for scaling events.
4. Test your setup to ensure that jobs are correctly scaled up and down based on your criteria.