Scaling Large Language Model Inference using Elastic Kubernetes

Question

Pulumi · Accepted Answer

Scaling large language models, such as GPT-3 or BERT, requires significant computational resources, especially if you need to serve a high volume of inference requests. You can accomplish this by setting up an Elastic Kubernetes Service (EKS), which can automatically scale your resources based on demand.

Elastic Kubernetes Service (EKS) is a managed service provided by AWS that makes it easier to deploy, manage, and scale containerized applications using Kubernetes.

Here's how you can use Pulumi to set up an EKS cluster that scales based on the compute and memory demands of your large language model inference service:

1. **EKS Cluster**: First, you create an EKS cluster. This is the central management entity for your Kubernetes environment on AWS.
2. **Node Groups**: Within the EKS cluster, you define node groups. These node groups can consist of different instance types that might be optimized for machine learning workloads, such as those belonging to AWS's p3 or g4 instance families, which are equipped with NVIDIA GPUs.
3. **Autoscaling**: Configure autoscaling policies for your node groups to automatically scale the number of instances based on the CPU and memory pressure. If the load on your inference service grows, EKS can add more nodes to the node group. Similarly, if the load decreases, it can remove unneeded nodes to help you manage costs.
4. **GPU Support**: If using GPUs, ensure that the cluster and node groups are configured with the right AMIs and resource types that support GPU.
5. **Horizontal Pod Autoscaler**: On top of the node-level scaling, Kubernetes also offers a Horizontal Pod Autoscaler (HPA), which automatically scales the number of pods in a deployment based on observed CPU or memory utilization.

Below is a Pulumi program in Python that creates an EKS cluster, a node group with autoscaling enabled, and sets up the necessary AWS and Kubernetes resources to support GPU-based workloads, assuming that is a requirement for your language models.

```python
import pulumi
import pulumi_eks as eks

# Create an EKS cluster with the default configuration.
cluster = eks.Cluster('example-cluster',
                      # The desired Kubernetes master version. If you're using GPUs, make sure to specify
                      # a version that is compatible with the Kubernetes device plugins for NVIDIA GPUs
                      version='1.21')

# Define the GPU instance type that is required for your language model inference. For example,
# 'p3.2xlarge' or 'g4dn.xlarge' are AWS instance types that come with NVIDIA GPUs.
gpu_instance_type = 'g4dn.xlarge'

# Define a managed node group using GPU instances and enable autoscaling.
gpu_node_group = eks.ManagedNodeGroup('gpu-node-group',
                                      cluster=cluster.core,
                                      instance_type=gpu_instance_type,
                                      desired_capacity=1,
                                      min_size=1,  # Minimum size for the auto-scaling group
                                      max_size=5,  # Maximum size for the auto-scaling group
                                      labels={'ondemand': 'true'},
                                      tags={
                                          'Name': 'pulumi-eks-gpu-node-group'
                                      },
                                      # Ensure that the nodes use the correct AMI for GPU workloads
                                      # Refer to the AWS documentation for the appropriate AMI based on your region and requirements
                                      )

# Export the clusters' kubeconfig.
pulumi.export('kubeconfig', cluster.kubeconfig)
```

### Explanation

1. **EKS Cluster**: We create an EKS cluster with a specific Kubernetes version. It's essential to pick a version compatible with your workloads and any specific plugins or tools you plan to use.

2. **GPU Node Group**: The `ManagedNodeGroup` is created to host the GPU instances. The `instance_type` is set based on the GPU requirements of your large language model. Autoscaling is set up with minimum and maximum sizes.

3. **Exports**: The kubeconfig is exported to enable interaction with the cluster using `kubectl` or other Kubernetes tools. This is the configuration needed to connect to your Kubernetes cluster.

4. **GPU AMIs**: You have to ensure that the appropriate AMI for GPU workloads is used. Depending on your workloads you might need a custom AMI that includes specific versions of CUDA or machine learning libraries.

5. **Autoscaling**: The min and max restrictions allow for autoscaling of node groups depending on the load.

Make sure to customize instance types, scaling policies, and Kubernetes versions based on the inference load your large language model requires and the specifics of the cloud provider region you're deploying to.