Inference serving language models in OCI-compliant model containers

Procedure

1. Create a Python virtual environment and install the huggingface_hub Python library:

   python3 -m venv venv && \
   source venv/bin/activate && \
   pip install --upgrade pip && \
   pip install huggingface_hub

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2. Create a model downloader Python script:

   vi download_model.py

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3. Add the following content to the download_model.py file, adjusting the value for model_repo as required:

   from huggingface_hub import snapshot_download
   
   # Specify the Hugging Face repository containing the model
   model_repo = "ibm-granite/granite-3.1-2b-instruct"
   snapshot_download(
       repo_id=model_repo,
       local_dir="/models",
       allow_patterns=["*.safetensors", "*.json", "*.txt"],
   )

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4. Create a Dockerfile for the modelcar:

   FROM registry.access.redhat.com/ubi9/python-311:latest as base
   
   USER root
   
   RUN pip install huggingface-hub
   
   # Download the model file from Hugging Face
   COPY download_model.py .
   
   RUN python download_model.py
   
   # Final image containing only the essential model files
   FROM registry.access.redhat.com/ubi9/ubi-micro:9.4
   
   # Copy the model files from the base container
   COPY --from=base /models /models
   
   USER 1001

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5. Build the modelcar image:

   podman build . -t modelcar-example:latest --platform linux/amd64

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   Example output

   Successfully tagged localhost/modelcar-example:latest

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6. Push the modelcar image to the container registry. For example:

   $ podman push modelcar-example:latest quay.io/<your_model_registry>/modelcar-example:latest

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   Example output

   Getting image source signatures
   Copying blob b2ed7134f853 done
   Copying config 4afd393610 done
   Writing manifest to image destination
   Storing signatures

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Procedure

1. Open a terminal on your server host, and log in to registry.redhat.io:

   $ podman login registry.redhat.io

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2. Optional: Log in to the container registry where your modelcar container image is stored. For example:

   $ podman login quay.io

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3. Pull the relevant NVIDIA CUDA image by running the following command:

   $ podman pull registry.redhat.io/rhaiis/vllm-cuda-rhel9:3.3.0

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4. If your system has SELinux enabled, configure SELinux to allow device access:

   $ sudo setsebool -P container_use_devices 1

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5. Create a folder that you will later mount as a volume in the container. Adjust the container permissions so that the container can use it.

   $ mkdir -p rhaiis-cache

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   $ chmod g+rwX rhaiis-cache

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6. Start the AI Inference Server container image. Run the following commands:

   1. For NVIDIA CUDA accelerators, if the host system has multiple GPUs and uses NVSwitch, then start NVIDIA Fabric Manager. To detect if your system is using NVSwitch, first check if files are present in /proc/driver/nvidia-nvswitch/devices/, and then start NVIDIA Fabric Manager. Starting NVIDIA Fabric Manager requires root privileges.

      $ ls /proc/driver/nvidia-nvswitch/devices/

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      Example output

      0000:0c:09.0  0000:0c:0a.0  0000:0c:0b.0  0000:0c:0c.0  0000:0c:0d.0  0000:0c:0e.0

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      $ systemctl start nvidia-fabricmanager

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      Important

      NVIDIA Fabric Manager is only required on systems with multiple GPUs that use NVSwitch. For more information, see NVIDIA Server Architectures.

      1. Check that the Red Hat AI Inference Server container can access NVIDIA GPUs on the host by running the following command:

         $ podman run --rm -it \
         --security-opt=label=disable \
         --device nvidia.com/gpu=all \
         nvcr.io/nvidia/cuda:12.4.1-base-ubi9 \
         nvidia-smi

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         Example output

         +-----------------------------------------------------------------------------------------+
         | NVIDIA-SMI 570.124.06             Driver Version: 570.124.06     CUDA Version: 12.8     |
         |-----------------------------------------+------------------------+----------------------+
         | GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
         | Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
         |                                         |                        |               MIG M. |
         |=========================================+========================+======================|
         |   0  NVIDIA A100-SXM4-80GB          Off |   00000000:08:01.0 Off |                    0 |
         | N/A   32C    P0             64W /  400W |       1MiB /  81920MiB |      0%      Default |
         |                                         |                        |             Disabled |
         +-----------------------------------------+------------------------+----------------------+
         |   1  NVIDIA A100-SXM4-80GB          Off |   00000000:08:02.0 Off |                    0 |
         | N/A   29C    P0             63W /  400W |       1MiB /  81920MiB |      0%      Default |
         |                                         |                        |             Disabled |
         +-----------------------------------------+------------------------+----------------------+
         
         +-----------------------------------------------------------------------------------------+
         | Processes:                                                                              |
         |  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
         |        ID   ID                                                               Usage      |
         |=========================================================================================|
         |  No running processes found                                                             |
         +-----------------------------------------------------------------------------------------+

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      2. Start the AI Inference Server container with the modelcar container image mounted:

         $ podman run --rm -it \
           --device nvidia.com/gpu=all \
           --security-opt=label=disable \
           --shm-size=4g \
           --userns=keep-id:uid=1001 \
           -p 8000:8000 \
           -e HF_HUB_OFFLINE=1 \
           -e TRANSFORMERS_OFFLINE=1 \
           --mount type=image,source=registry.redhat.io/rhelai1/modelcar-granite-8b-code-instruct:1.4-1739210683,destination=/model \
           -v ./rhaiis-cache:/opt/app-root/src/.cache:Z \
           registry.redhat.io/rhaiis/vllm-cuda-rhel9:3.3.0 \
           --model /model/models \
           --port 8000 \
           --dtype auto \
           --max-model-len 4096 \
           --tensor-parallel-size 2 \
           --served-model-name rhelai1/modelcar-granite-8b-code-instruct

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         Where:

         --security-opt=label=disable

         Disables SELinux label relabeling for volume mounts. Required for systems where SELinux is enabled. Without this option, the container might fail to start.

         --shm-size=4g

         Specifies the shared memory size. Increase to 8GB if you experience shared memory issues.

         --userns=keep-id:uid=1001

         Maps the host UID to the effective UID of the vLLM process in the container. Alternatively, you can pass --user=0, but this is less secure because it runs vLLM as root inside the container.

         -e HF_HUB_OFFLINE=1

         Prevents Hugging Face Hub from connecting to the internet.

         -e TRANSFORMERS_OFFLINE=1

         Configures the Transformers library to use only the locally mounted model.

         --mount type=image,source=registry.redhat.io/rhelai1/modelcar-granite-8b-code-instruct:1.4-1739210683,destination=/model

         Mounts the modelcar container directly inside the running rhaiis/vllm-cuda-rhel9 Red Hat AI Inference Server container.

         -v ./rhaiis-cache:/opt/app-root/src/.cache:Z

         Mounts the cache directory with SELinux context. The :Z suffix is required for systems where SELinux is enabled. On Debian, Ubuntu, or Docker without SELinux, omit the :Z suffix.

         --model /model/models

         Specifies the path to the model directory inside the container.

         --tensor-parallel-size 2

         Specifies the number of GPUs to use for tensor parallelism. Set this value to match the number of available GPUs.

         --served-model-name rhelai1/modelcar-granite-8b-code-instruct

         Specifies a user-friendly name for the served model. If not set, the name defaults to the value of the --model parameter.

Procedure

1. Create the Docker secret so that the cluster can download the Red Hat AI Inference Server image from the container registry. For example, to create a Secret CR that contains the contents of your local ~/.docker/config.json file, run the following command:

   oc create secret generic docker-secret --from-file=.dockercfg=$HOME/.docker/config.json --type=kubernetes.io/dockercfg -n rhaiis-namespace

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2. Create a PersistentVolumeClaim (PVC) custom resource (CR) and apply it in the cluster. The following example PVC CR uses a default IBM VPC Block persistence volume.

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: model-cache
     namespace: rhaiis-namespace
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 20Gi
     storageClassName: ibmc-vpc-block-10iops-tier

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   Note

   Configuring cluster storage to meet your requirements is outside the scope of this procedure. For more detailed information, see Configuring persistent storage.

3. Create a Deployment custom resource (CR) that pulls the modelcar image and deploys the Red Hat AI Inference Server container. Reference the following example Deployment CR, which uses AI Inference Server to serve a modelcar image.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: rhaiis-oci-deploy
     namespace: rhaiis-namespace
     labels:
       app: granite
   spec:
     replicas: 0
     selector:
       matchLabels:
         app: rhaiis-oci-deploy
     template:
       metadata:
         labels:
           app: rhaiis-oci-deploy
       spec:
         imagePullSecrets:
           - name: docker-secret
         volumes:
           - name: model-volume
             persistentVolumeClaim:
               claimName: model-cache
           - name: shm
             emptyDir:
               medium: Memory
               sizeLimit: "2Gi"
           - name: oci-auth
             secret:
               secretName: docker-secret
               items:
                 - key: .dockercfg
                   path: config.json
         initContainers:
           - name: fetch-model
             image: ghcr.io/oras-project/oras:v1.2.0
             command: ["/bin/sh","-c"]
             args:
               - |
                 set -e
                 # Only pull if /model is empty
                 if [ -z "$(ls -A /model)" ]; then
                   echo "Pulling model…"
                   # Update with the modelcar container image registry URL
                   oras pull <YOUR_MODELCAR_REGISTRY_URL> \
                     --output /model \
                 else
                   echo "Model already present, skipping pull"
                 fi
             volumeMounts:
               - name: model-volume
                 mountPath: /model
               - name: oci-auth
                 mountPath: /auth
                 readOnly: true
         containers:
           - name: granite
             image: 'registry.redhat.io/rhaiis/vllm-cuda-rhel9@sha256:a6645a8e8d7928dce59542c362caf11eca94bb1b427390e78f0f8a87912041cd'
             imagePullPolicy: IfNotPresent
             env:
               - name: VLLM_SERVER_DEV_MODE
                 value: '1'
             command:
               - python
               - '-m'
               - vllm.entrypoints.openai.api_server
             args:
               - '--port=8000'
               - '--model=/model'
               - '--served-model-name=ibm-granite/granite-3.1-2b-instruct'
               - '--tensor-parallel-size=1'
             resources:
               limits:
                 cpu: '10'
                 nvidia.com/gpu: '1'
                 memory: 16Gi
               requests:
                 cpu: '2'
                 memory: 6Gi
                 nvidia.com/gpu: '1'
             volumeMounts:
               - name: model-volume
                 mountPath: /model
               - name: shm
                 mountPath: /dev/shm
         restartPolicy: Always

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   Where:

   claimName: model-cache

   Specifies the persistent volume claim name. The value of spec.template.spec.volumes.persistentVolumeClaim.claimName must match the name of the PVC that you created.

   initContainers:

   Defines a container that runs before the main application container to download the required modelcar image. The model pull step is skipped if the model directory has already been populated, for example, from a previous deployment.

   --served-model-name=ibm-granite/granite-3.1-2b-instruct

   Specifies a user-friendly name for the served model. Update this value to match the model that you are deploying.

   mountPath: /dev/shm

   Mounts the shared memory volume required by the NVIDIA Collective Communications Library (NCCL). Tensor parallel vLLM deployments fail without this volume mount.

4. Increase the deployment replica count to the required number. For example, run the following command:

   oc scale deployment granite -n rhaiis-namespace --replicas=1

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5. Optional: Watch the deployment and ensure that it succeeds:

   $ oc get deployment -n rhaiis-namespace --watch

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   Example output

   NAME                READY   UP-TO-DATE   AVAILABLE   AGE
   rhaiis-oci-deploy   0/1     1            0           2s
   rhaiis-oci-deploy   1/1     1            1           14s

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6. Create a Service CR for the model inference. For example:

   apiVersion: v1
   kind: Service
   metadata:
     name: rhaiis-oci-deploy
     namespace: rhaiis-namespace
   spec:
     selector:
       app: rhaiis-oci-deploy
     ports:
       - name: http
         port: 80
         targetPort: 8000

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7. Optional: Create a Route CR to enable public access to the model. For example:

   apiVersion: route.openshift.io/v1
   kind: Route
   metadata:
     name: rhaiis-oci-deploy
     namespace: rhaiis-namespace
   spec:
     to:
       kind: Service
       name: rhaiis-oci-deploy
     port:
       targetPort: http

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8. Get the URL for the exposed route. Run the following command:

   $ oc get route granite -n rhaiis-namespace -o jsonpath='{.spec.host}'

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   Example output

   rhaiis-oci-deploy-rhaiis-namespace.apps.example.com

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