# Production stack

Deploying vLLM on Kubernetes is a scalable and efficient way to serve machine learning models. This guide walks you through deploying vLLM using the [vLLM production stack](https://github.com/vllm-project/production-stack). Born out of a Berkeley-UChicago collaboration, [vLLM production stack](https://github.com/vllm-project/production-stack) is an officially released, production-optimized codebase under the [vLLM project](https://github.com/vllm-project), designed for LLM deployment with:

* **Upstream vLLM compatibility** – It wraps around upstream vLLM without modifying its code.
* **Ease of use** – Simplified deployment via Helm charts and observability through Grafana dashboards.
* **High performance** – Optimized for LLM workloads with features like multimodel support, model-aware and prefix-aware routing, fast vLLM bootstrapping, and KV cache offloading with [LMCache](https://github.com/LMCache/LMCache) (wired up in vLLM via `--kv-offloading-backend lmcache`; see the [LMCache examples](https://github.com/vllm-project/vllm/tree/main/examples/disaggregated/lmcache) and [docs.lmcache.ai](https://docs.lmcache.ai)), among others.

If you are new to Kubernetes, don't worry: in the vLLM production stack [repo](https://github.com/vllm-project/production-stack), we provide a step-by-step [guide](https://github.com/vllm-project/production-stack/blob/main/tutorials/00-install-kubernetes-env.md) and a [short video](https://www.youtube.com/watch?v=EsTJbQtzj0g) to set up everything and get started in **4 minutes**!

## Pre-requisite

Ensure that you have a running Kubernetes environment with GPU (you can follow [this tutorial](https://github.com/vllm-project/production-stack/blob/main/tutorials/00-install-kubernetes-env.md) to install a Kubernetes environment on a bare-metal GPU machine).

## Deployment using vLLM production stack

The standard vLLM production stack is installed using a Helm chart. You can run this [bash script](https://github.com/vllm-project/production-stack/blob/main/utils/install-helm.sh) to install Helm on your GPU server.

To install the vLLM production stack, run the following commands on your desktop:

```bash
sudo helm repo add vllm https://vllm-project.github.io/production-stack
sudo helm install vllm vllm/vllm-stack -f tutorials/assets/values-01-minimal-example.yaml
```

This will instantiate a vLLM-production-stack-based deployment named `vllm` that runs a small LLM (Facebook opt-125M model).

### Validate Installation

Monitor the deployment status using:

```bash
sudo kubectl get pods
```

And you will see that pods for the `vllm` deployment will transit to `Running` state.

```text
NAME                                           READY   STATUS    RESTARTS   AGE
vllm-deployment-router-859d8fb668-2x2b7        1/1     Running   0          2m38s
vllm-opt125m-deployment-vllm-84dfc9bd7-vb9bs   1/1     Running   0          2m38s
```

!!! note
    It may take some time for the containers to download the Docker images and LLM weights.

### Send a Query to the Stack

Forward the `vllm-router-service` port to the host machine:

```bash
sudo kubectl port-forward svc/vllm-router-service 30080:80
```

And then you can send out a query to the OpenAI-compatible API to check the available models:

```bash
curl -o- http://localhost:30080/v1/models
```

??? console "Output"

    ```json
    {
      "object": "list",
      "data": [
        {
          "id": "facebook/opt-125m",
          "object": "model",
          "created": 1737428424,
          "owned_by": "vllm",
          "root": null
        }
      ]
    }
    ```

To send an actual chatting request, you can issue a curl request to the OpenAI `/completion` endpoint:

```bash
curl -X POST http://localhost:30080/v1/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "facebook/opt-125m",
    "prompt": "Once upon a time,",
    "max_tokens": 10
  }'
```

??? console "Output"

    ```json
    {
      "id": "completion-id",
      "object": "text_completion",
      "created": 1737428424,
      "model": "facebook/opt-125m",
      "choices": [
        {
          "text": " there was a brave knight who...",
          "index": 0,
          "finish_reason": "length"
        }
      ]
    }
    ```

### Uninstall

To remove the deployment, run:

```bash
sudo helm uninstall vllm
```

---

### (Advanced) Configuring vLLM production stack

The core vLLM production stack configuration is managed with YAML. Here is the example configuration used in the installation above:

??? code "Yaml"

    ```yaml
    servingEngineSpec:
      runtimeClassName: ""
      modelSpec:
      - name: "opt125m"
        repository: "vllm/vllm-openai"
        tag: "latest"
        modelURL: "facebook/opt-125m"

        replicaCount: 1

        requestCPU: 6
        requestMemory: "16Gi"
        requestGPU: 1

        pvcStorage: "10Gi"
    ```

In this YAML configuration:

* **`modelSpec`** includes:
    * `name`: A nickname that you prefer to call the model.
    * `repository`: Docker repository of vLLM.
    * `tag`: Docker image tag.
    * `modelURL`: The LLM model that you want to use.
* **`replicaCount`**: Number of replicas.
* **`requestCPU` and `requestMemory`**: Specifies the CPU and memory resource requests for the pod.
* **`requestGPU`**: Specifies the number of GPUs required.
* **`pvcStorage`**: Allocates persistent storage for the model.

!!! note
    If you intend to set up two pods, please refer to this [YAML file](https://github.com/vllm-project/production-stack/blob/main/tutorials/assets/values-01-2pods-minimal-example.yaml).

!!! tip
    vLLM production stack offers many more features (*e.g.* CPU offloading and a wide range of routing algorithms). Please check out these [examples and tutorials](https://github.com/vllm-project/production-stack/tree/main/tutorials) and our [repo](https://github.com/vllm-project/production-stack) for more details!
