.. _deploying_with_k8s:

Deploying with Kubernetes
==========================

Using Kubernetes to deploy vLLM is a scalable and efficient way to serve machine learning models. This guide will walk you through the process of deploying vLLM with Kubernetes, including the necessary prerequisites, steps for deployment, and testing.

Prerequisites
-------------
Before you begin, ensure that you have the following:

- A running Kubernetes cluster
- NVIDIA Kubernetes Device Plugin (`k8s-device-plugin`): This can be found at `https://github.com/NVIDIA/k8s-device-plugin/`
- Available GPU resources in your cluster

Deployment Steps
----------------

1.  **Create a PVC , Secret and Deployment for vLLM**


PVC is used to store the model cache and it is optional, you can use hostPath or other storage options

.. code-block:: yaml

  apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
    name: mistral-7b
    namespace: default
  spec:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 50Gi
    storageClassName: default
    volumeMode: Filesystem

Secret is optional and only required for accessing gated models, you can skip this step if you are not using gated models

.. code-block:: yaml

  apiVersion: v1
  kind: Secret
  metadata:
    name: hf-token-secret
    namespace: default
  type: Opaque
  data:
    token: "REPLACE_WITH_TOKEN"


Create a deployment file for vLLM to run the model server. The following example deploys the `Mistral-7B-Instruct-v0.3` model:

.. code-block:: yaml

  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: mistral-7b
    namespace: default
    labels:
      app: mistral-7b
  spec:
    replicas: 1
    selector:
      matchLabels:
        app: mistral-7b
    template:
      metadata:
        labels:
          app: mistral-7b
      spec:
        volumes:
        - name: cache-volume
          persistentVolumeClaim:
            claimName: mistral-7b
        # vLLM needs to access the host's shared memory for tensor parallel inference.
        - name: shm
          emptyDir:
            medium: Memory
            sizeLimit: "2Gi"
        containers:
        - name: mistral-7b
          image: vllm/vllm-openai:latest
          command: ["/bin/sh", "-c"]
          args: [
            "vllm serve mistralai/Mistral-7B-Instruct-v0.3 --trust-remote-code --enable-chunked-prefill --max_num_batched_tokens 1024"
          ]
          env:
          - name: HUGGING_FACE_HUB_TOKEN
            valueFrom:
              secretKeyRef:
                name: hf-token-secret
                key: token
          ports:
          - containerPort: 8000
          resources:
            limits:
              cpu: "10"
              memory: 20G
              nvidia.com/gpu: "1"
            requests:
              cpu: "2"
              memory: 6G
              nvidia.com/gpu: "1"
          volumeMounts:
          - mountPath: /root/.cache/huggingface
            name: cache-volume
          - name: shm
            mountPath: /dev/shm
          livenessProbe:
            httpGet:
              path: /health
              port: 8000
            initialDelaySeconds: 60
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /health
              port: 8000
            initialDelaySeconds: 60
            periodSeconds: 5

2. **Create a Kubernetes Service for vLLM**

Next, create a Kubernetes Service file to expose the `mistral-7b` deployment:

.. code-block:: yaml

    apiVersion: v1
    kind: Service
    metadata:
      name: mistral-7b
      namespace: default
    spec:
      ports:
      - name: http-mistral-7b
        port: 80
        protocol: TCP
        targetPort: 8000
      # The label selector should match the deployment labels & it is useful for prefix caching feature
      selector:
        app: mistral-7b
      sessionAffinity: None
      type: ClusterIP

3. **Deploy and Test**

Apply the deployment and service configurations using ``kubectl apply -f <filename>``:

.. code-block:: console

    kubectl apply -f deployment.yaml
    kubectl apply -f service.yaml

To test the deployment, run the following ``curl`` command:

.. code-block:: console

    curl http://mistral-7b.default.svc.cluster.local/v1/completions \
      -H "Content-Type: application/json" \
      -d '{
            "model": "mistralai/Mistral-7B-Instruct-v0.3",
            "prompt": "San Francisco is a",
            "max_tokens": 7,
            "temperature": 0
          }'

If the service is correctly deployed, you should receive a response from the vLLM model.

Conclusion
----------
Deploying vLLM with Kubernetes allows for efficient scaling and management of ML models leveraging GPU resources. By following the steps outlined above, you should be able to set up and test a vLLM deployment within your Kubernetes cluster. If you encounter any issues or have suggestions, please feel free to contribute to the documentation.
