Kubernetes Jobs for Parallel AI Model Training Tasks

Question

Pulumi · Accepted Answer

Kubernetes Jobs are ideal for tasks that execute once and stop, but might need to run multiple times in parallel, which is exactly what is needed for parallel AI model training tasks. In Kubernetes, a Job creates one or more Pods and ensures that a specified number of them successfully terminate. When the specified number of successful completions is reached, the job is complete. If a Pod in a Job fails, the Job controller starts a new Pod for you.

In a Kubernetes cluster where you are training AI models, each parallel task can be a Job, ensuring that the model trains to completion or fails after a certain number of retries. One common pattern for parallel tasks is to use Jobs with a parallelism parameter, which dictates how many Pods to run in parallel. The completion count defines how many times the tasks should be successfully completed.

Below is a Pulumi program in Python that would set up such a Kubernetes Job for parallel AI model training tasks. This program assumes that you have a container image ready for the AI model training task with the appropriate training script inside the container.

Before running this Pulumi program, ensure you have Pulumi installed, have access to a Kubernetes cluster, and have kubectl configured to connect to your cluster.

import pulumi
import pulumi_kubernetes as k8s

# Define the container image that includes the AI training logic.
# This image should be built and pushed to a registry that your K8s cluster has access to.
training_container_image = "your-registry/ai-training:latest"

# Define the job specifications, such as parallelism and completions.
# 'parallelism' specifies the number of Pods to run concurrently.
# 'completions' specifies the number of successful pod completions required.
job_specifications = {
    "parallelism": 5,  # This will run 5 Pods in parallel.
    "completions": 5,  # This ensures each Pod completes its job 5 times.
    "template": {      # This is the template for the Pods that the Job will create.
        "spec": {
            "containers": [{
                "name": "ai-model-training",    # Name of the container in the Pod.
                "image": training_container_image,  # The image to use for the training tasks.
                # Define environment variables, volumes or other configurations needed.
            }],
            "restartPolicy": "Never"  # Pods don't restart once their task completes.
        }
    }
}

# Use the Job class from the Kubernetes provider for Pulumi to create a Kubernetes Job.
# The 'metadata' field defines the name and namespace (optional) for the Job.
ai_training_job = k8s.batch.v1.Job(
    "ai-model-training-job",
    spec=k8s.batch.v1.JobSpecArgs(**job_specifications)
)

# Export the job name so you can easily locate it with 'kubectl'.
pulumi.export('job_name', ai_training_job.metadata["name"])

This Pulumi program describes a Kubernetes Job named ai-model-training-job that will create 5 Pods in parallel (parallelism). Each Pod runs a container based on your custom ai-training Docker image (your-registry/ai-training:latest). The Job requires that each Pod successfully complete its task 5 times before it is considered complete (completions). The restartPolicy is set to Never, indicating that a Pod does not restart once it completes its task; instead, the Job controller starts new Pods if needed.

To deploy this program, save the code in a file with a .py extension, for example train.py, and then run pulumi up in the same directory. This will execute the Pulumi program, which will, in turn, create the Kubernetes Job in your cluster according to the specifications.

You can monitor job progress with kubectl get jobs and check the details and status of individual Pods created by the Job with kubectl describe job <job_name> and kubectl logs <pod_name>. Replace <job_name> and <pod_name> with your actual job and pod names.