Deploy InferenceService with Transformer using Feast online feature store¶

Transformer is an InferenceService component which does pre/post processing alongside with model inference. In this example, instead of typical input transformation of raw data to tensors, we demonstrate a use case of online feature augmentation as part of preprocessing. We use a Feast Transformer to gather online features, run inference with a SKLearn predictor, and leave post processing as pass-through.

Before you begin¶

1. Your ~/.kube/config should point to a cluster with KServe installed.
2. Your cluster's Istio Ingress gateway must be network accessible.
3. You can find the code samples on kserve repository.

Create the Redis server¶

This example uses the Redis as the online store. Deploy the Redis server using the below command.

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-server
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis-server
  template:
    metadata:
      labels:
        app: redis-server
        name: redis-server
    spec:
      containers:
        - name: redis-server
          image: redis
          args: [ "--appendonly", "yes" ]
          ports:
            - name: redis-server
              containerPort: 6379
          env:
            - name: ALLOW_EMPTY_PASSWORD
              value: "yes"
---
apiVersion: v1
kind: Service
metadata:
  name: redis-service
spec:
  type: LoadBalancer
  selector:
    app: redis-server
  ports:
    - protocol: TCP
      port: 6379
      targetPort: 6379
EOF

$ deployment.apps/redis-server created
$ service/redis-service created

Create the Feast server¶

Build Feature Store Initializer docker image¶

The feature store initializer is a init container which initializes a new sample feature repository, populate the online store with sample driver data and copies the feature repository to the volume mount. The feature store initializer dockerfile can be found in the code example directory. Checkout the feast code example and under the example directory run the commands as following:

docker build -t $USERNAME/feature-store-initializer:latest -f feature_store_initializer.Dockerfile .

docker push $USERNAME/feature-store-initializer:latest

Build Feast server docker image¶

The feast server dockerfile can be found in the code example directory.

docker build -t $USERNAME/feast-server:latest -f feast_server.Dockerfile .

docker push $USERNAME/feast-server:latest

Deploy Feast server¶

Wait until the Redis Deployment is available. Now, update the init container and container's image field in the below command and deploy the Feast server.

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: feature-server
spec:
  replicas: 1
  selector:
    matchLabels:
      app: feature-server
  template:
    metadata:
      labels:
        app: feature-server
        name: feature-server
    spec:
      initContainers:
        - name: feature-store-initializer
          image: "{username}/feature-store-initializer:latest"
          volumeMounts:
            - mountPath: /mnt
              name: feature-store-volume
      containers:
        - name: feature-server
          image: "{username}/feast-server:latest"
          args: [ -c, /mnt/driver_feature_repo/feature_repo, serve, -h, 0.0.0.0 ]
          ports:
            - name: feature-server
              containerPort: 6566
          resources:
            requests:
              memory: "64Mi"
              cpu: "250m"
            limits:
              memory: "128Mi"
              cpu: "500m"
          volumeMounts:
            - mountPath: /mnt
              name: feature-store-volume
      volumes:
        - name: feature-store-volume
          emptyDir:
            sizeLimit: 100Mi

---
apiVersion: v1
kind: Service
metadata:
  name: feature-server-service
spec:
  type: LoadBalancer
  selector:
    app: feature-server
  ports:
    - protocol: TCP
      port: 6566
      targetPort: 6566
EOF

$ deployment.apps/feature-server created
$ service/feature-server-service created

Create a Transformer with Feast¶

Extend the Model class and implement pre/post processing functions¶

KServe.Model base class mainly defines three handlers preprocess, predict and postprocess, these handlers are executed in sequence, the output of the preprocess is passed to predict as the input, when predictor_host is passed the predict handler by default makes a HTTP call to the predictor url and gets back a response which then passes to postproces handler. KServe automatically fills in the predictor_host for Transformer and handle the call to the Predictor, for gRPC predictor currently you would need to overwrite the predict handler to make the gRPC call.

To implement a Transformer you can derive from the base Model class and then overwrite the preprocess and postprocess handler to have your own customized transformation logic.

We created a class, DriverTransformer, which extends Model for this driver ranking example. It takes additional arguments for the transformer to interact with Feast:

• feast_serving_url: The Feast serving URL, in the form of <host_name:port> or <ip:port>
• entity_id_name: The name of the entity ID for which to retrieve features from the Feast feature store
• feature_refs: The feature references for the features to be retrieved

Build Transformer docker image¶

The driver transformer dockerfile can be found in the code example directory. Checkout the feast code example and under the example directory run the commands as following:

docker build -t $USERNAME/driver-transformer:latest -f driver_transformer.Dockerfile .

docker push $USERNAME/driver-transformer:latest

Create the InferenceService¶

In the Feast Transformer image we packaged the driver transformer class so KServe knows to use the preprocess implementation to augment inputs with online features before making model inference requests. Then the InferenceService uses SKLearn to serve the driver ranking model, which is trained with Feast offline features, available in a gcs bucket specified under storageUri. Update the container's image field and the feast_serving_url argument to create the InferenceService, which includes a Feast Transformer and a SKLearn Predictor.

cat <<EOF | kubectl apply -f -
apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "sklearn-driver-transformer"
spec:
  transformer:
    containers:
      - image: "kserve/driver-transformer:latest"
        name: driver-container
        command:
          - "python"
          - "-m"
          - "driver_transformer"
        args:
          - --feast_serving_url
          - "feature-server-service.default.svc.cluster.local:6566"
          - --entity_id_name
          - "driver_id"
          - --feature_refs
          - "driver_hourly_stats:conv_rate"
          - "driver_hourly_stats:acc_rate"
          - "driver_hourly_stats:avg_daily_trips"
  predictor:
    model:
      modelFormat:
        name: sklearn
      storageUri: "gs://kfserving-examples/models/feast/driver"
EOF

cat <<EOF | kubectl apply -f -
apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "sklearn-driver-transformer"
spec:
  transformer:
    containers:
      - image: "kserve/driver-transformer:latest"
        name: driver-container
        command:
          - "python"
          - "-m"
          - "driver_transformer"
        args:
          - --feast_serving_url
          - "feature-server-service.default.svc.cluster.local:6566"
          - --entity_id_name
          - "driver_id"
          - --feature_refs
          - "driver_hourly_stats:conv_rate"
          - "driver_hourly_stats:acc_rate"
          - "driver_hourly_stats:avg_daily_trips"
  predictor:
    sklearn:
      storageUri: "gs://kfserving-examples/models/feast/driver"
EOF

$ inferenceservice.serving.kserve.io/sklearn-driver-transformer created

Run a prediction¶

Prepare the inputs for the inference request. Copy the following Json into a file named driver-input.json.

{
  "instances": [[1001], [1002], [1003], [1004], [1005]]
}

SERVICE_NAME=sklearn-driver-transformer
MODEL_NAME=sklearn-driver-transformer
INPUT_PATH=@./driver-input.json
SERVICE_HOSTNAME=$(kubectl get inferenceservice $SERVICE_NAME -o jsonpath='{.status.url}' | cut -d "/" -f 3)

curl -v -H "Host: ${SERVICE_HOSTNAME}" -d $INPUT_PATH http://${INGRESS_HOST}:${INGRESS_PORT}/v1/models/$MODEL_NAME:predict

> POST /v1/models/sklearn-driver-transformer:predict HTTP/1.1
> Host: sklearn-driver-transformer.default.example.com
> User-Agent: curl/7.85.0
> Accept: */*
> Content-Length: 57
> Content-Type: application/x-www-form-urlencoded
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< content-length: 115
< content-type: application/json
< date: Thu, 30 Mar 2023 09:46:52 GMT
< server: istio-envoy
< x-envoy-upstream-service-time: 112
< 
* Connection #0 to host 1.2.3.4 left intact
{"predictions":[0.45905828209879473,1.5118208033011165,0.21514156911776539,0.5555778492605103,0.49638665080127176]}