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Deploy Spark MLlib model with PMML InferenceService

Setup

  1. Install pyspark 3.0.x and pyspark2pmml 
    pip install pyspark~=3.0.0
pip install pyspark2pmml
  2. Get JPMML-SparkML jar

Train a Spark MLlib model and export to PMML file

Launch pyspark with --jars to specify the location of the JPMML-SparkML uber-JAR 

pyspark --jars ./jpmml-sparkml-executable-1.6.3.jar

Fitting a Spark ML pipeline: 

from pyspark.ml import Pipeline
from pyspark.ml.classification import DecisionTreeClassifier
from pyspark.ml.feature import RFormula

df = spark.read.csv("Iris.csv", header = True, inferSchema = True)

formula = RFormula(formula = "Species ~ .")
classifier = DecisionTreeClassifier()
pipeline = Pipeline(stages = [formula, classifier])
pipelineModel = pipeline.fit(df)

from pyspark2pmml import PMMLBuilder

pmmlBuilder = PMMLBuilder(sc, df, pipelineModel)

pmmlBuilder.buildFile("DecisionTreeIris.pmml")

Upload the DecisionTreeIris.pmml to a GCS bucket. 

gsutil cp ./DecisionTreeIris.pmml gs://$BUCKET_NAME/sparkpmml/model.pmml

Test the Model locally

For testing the model locally, please refer the pmml server documentation.

Deploy Spark MLlib model with V1 protocol

Create the InferenceService with PMMLServer

Create the InferenceService with pmml predictor and specify the storageUri with bucket location you uploaded to

apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "spark-pmml"
spec:
  predictor:
    model:
      modelFormat:
        name: pmml
      storageUri: gs://kfserving-examples/models/sparkpmml

apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "spark-pmml"
spec:
  predictor:
    pmml:
      storageUri: gs://kfserving-examples/models/sparkpmml

Warning

The pmmlserver is based on Py4J and that doesn't support multi-process mode, so we can't set spec.predictor.containerConcurrency. If you want to scale the PMMLServer to improve prediction performance, you should set the InferenceService's resources.limits.cpu to 1 and scale the replica size.

Apply the InferenceService custom resource 

kubectl apply -f spark_pmml.yaml

Expected Output

$ inferenceservice.serving.kserve.io/spark-pmml created

Wait the InferenceService to be ready 

kubectl wait --for=condition=Ready inferenceservice spark-pmml
$ inferenceservice.serving.kserve.io/spark-pmml condition met

Run a prediction

The first step is to determine the ingress IP and ports and set INGRESS_HOST and INGRESS_PORT.

You can see an example payload below. Create a file named iris-input.json with the sample input. 

{
  "instances": [
    [5.1, 3.5, 1.4, 0.2]
  ]
}


MODEL_NAME=spark-pmml
INPUT_PATH=@./iris-input.json
SERVICE_HOSTNAME=$(kubectl get inferenceservice spark-pmml -o jsonpath='{.status.url}' | cut -d "/" -f 3)
curl -v -H "Host: ${SERVICE_HOSTNAME}" http://${INGRESS_HOST}:${INGRESS_PORT}/v1/models/$MODEL_NAME:predict -d $INPUT_PATH

Expected Output

* Connected to spark-pmml.default.35.237.217.209.xip.io (35.237.217.209) port 80 (#0)
> POST /v1/models/spark-pmml:predict HTTP/1.1
> Host: spark-pmml.default.35.237.217.209.xip.io
> User-Agent: curl/7.73.0
> Accept: */*
> Content-Length: 45
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 45 out of 45 bytes
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< content-length: 39
< content-type: application/json; charset=UTF-8
< date: Sun, 07 Mar 2021 19:32:50 GMT
< server: istio-envoy
< x-envoy-upstream-service-time: 14
<
* Connection #0 to host spark-pmml.default.35.237.217.209.xip.io left intact
{"predictions": [[1.0, 0.0, 1.0, 0.0]]}

Deploy the model with Open Inference Protocol

Deploy the Model with REST endpoint through InferenceService

Lastly, you will use KServe to deploy the trained model onto Kubernetes. For this, you will just need to use version v1beta1 of the InferenceService CRD and set the protocolVersion field to v2.

apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "spark-v2-iris"
spec:
  predictor:
    model:
      modelFormat:
        name: pmml
      protocolVersion: v2
      runtime: kserve-pmmlserver
      storageUri: "gs://kfserving-examples/models/sparkpmml"

Warning

The pmmlserver is based on Py4J and that doesn't support multi-process mode, so we can't set spec.predictor.containerConcurrency. If you want to scale the PMMLServer to improve prediction performance, you should set the InferenceService's resources.limits.cpu to 1 and scale the replica size.

kubectl apply -f spark-v2-iris.yaml

Test the Deployed Model

You can now test your deployed model by sending a sample request.

Note that this request needs to follow the Open Inference Protocol. You can see an example payload below. Create a file named iris-input-v2.json with the sample input.

{
  "inputs": [
    {
      "name": "input-0",
      "shape": [2, 4],
      "datatype": "FP32",
      "data": [
        [6.8, 2.8, 4.8, 1.4],
        [6.0, 3.4, 4.5, 1.6]
      ]
    }
  ]
}
Determine the ingress IP and port and set INGRESS_HOST and INGRESS_PORT. Now, you can use curl to send the inference request as:

SERVICE_HOSTNAME=$(kubectl get inferenceservice spark-v2-iris -o jsonpath='{.status.url}' | cut -d "/" -f 3)

curl -v \
  -H "Host: ${SERVICE_HOSTNAME}" \
  -H "Content-Type: application/json" \
  -d @./iris-input-v2.json \
  http://${INGRESS_HOST}:${INGRESS_PORT}/v2/models/spark-v2-iris/infer

Expected Output

{
  "model_name": "spark-v2-iris",
  "model_version": null,
  "id": "a187a478-c614-46ce-a7de-2f07871f43f3",
  "parameters": null,
  "outputs": [
    {
      "name": "Species",
      "shape": [
        2
      ],
      "datatype": "BYTES",
      "parameters": null,
      "data": [
        "versicolor",
        "versicolor"
      ]
    },
    {
      "name": "Probability_setosa",
      "shape": [
        2
      ],
      "datatype": "FP64",
      "parameters": null,
      "data": [
        0,
        0
      ]
    },
    {
      "name": "Probability_versicolor",
      "shape": [
        2
      ],
      "datatype": "FP64",
      "parameters": null,
      "data": [
        0.9074074074074074,
        0.9074074074074074
      ]
    },
    {
      "name": "Probability_virginica",
      "shape": [
        2
      ],
      "datatype": "FP64",
      "parameters": null,
      "data": [
        0.09259259259259259,
        0.09259259259259259
      ]
    },
    {
      "name": "Node_Id",
      "shape": [
        2
      ],
      "datatype": "BYTES",
      "parameters": null,
      "data": [
        "6",
        "6"
      ]
    }
  ]
}

Deploy the Model with GRPC endpoint through InferenceService

Create the inference service resource and expose the gRPC port using the below yaml.

Note

Currently, KServe only supports exposing either HTTP or gRPC port. By default, HTTP port is exposed.

apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "spark-v2-iris-grpc"
spec:
  predictor:
    model:
      modelFormat:
        name: pmml
      protocolVersion: v2
      runtime: kserve-pmmlserver
      storageUri: "gs://kfserving-examples/models/sparkpmml"
      ports:
        - name: h2c     # knative expects grpc port name to be 'h2c'
          protocol: TCP
          containerPort: 8081

apiVersion: "serving.kserve.io/v1beta1"
kind: "InferenceService"
metadata:
  name: "spark-v2-iris-grpc"
spec:
  predictor:
    model:
      modelFormat:
        name: pmml
      protocolVersion: v2
      runtime: kserve-pmmlserver
      storageUri: "gs://kfserving-examples/models/sparkpmml"
      ports:
        - name: grpc-port  # Istio requires the port name to be in the format <protocol>[-<suffix>]
          protocol: TCP
          containerPort: 8081

Warning

The pmmlserver is based on Py4J and that doesn't support multi-process mode, so we can't set spec.predictor.containerConcurrency. If you want to scale the PMMLServer to improve prediction performance, you should set the InferenceService's resources.limits.cpu to 1 and scale the replica size.

Apply the InferenceService yaml to get the gRPC endpoint

kubectl apply -f spark-v2-grpc.yaml

Test the deployed model with grpcurl

After the gRPC InferenceService becomes ready, grpcurl, can be used to send gRPC requests to the InferenceService.

# download the proto file
curl -O https://raw.githubusercontent.com/kserve/open-inference-protocol/main/specification/protocol/open_inference_grpc.proto

INPUT_PATH=iris-input-v2-grpc.json
PROTO_FILE=open_inference_grpc.proto
SERVICE_HOSTNAME=$(kubectl get inferenceservice spark-v2-iris-grpc -o jsonpath='{.status.url}' | cut -d "/" -f 3)
Determine the ingress IP and port and set INGRESS_HOST and INGRESS_PORT. Now, you can use curl to send the inference requests. The gRPC APIs follows the KServe prediction V2 protocol / Open Inference Protocol. For example, ServerReady API can be used to check if the server is ready:

grpcurl \
  -plaintext \
  -proto ${PROTO_FILE} \
  -authority ${SERVICE_HOSTNAME} \
  ${INGRESS_HOST}:${INGRESS_PORT} \
  inference.GRPCInferenceService.ServerReady

Expected Output

{
  "ready": true
}

You can test the deployed model by sending a sample request with the below payload. Notice that the input format differs from the in the previous REST endpoint example. Prepare the inference input inside the file named iris-input-v2-grpc.json. 

{
  "model_name": "spark-v2-iris-grpc",
  "inputs": [
    {
      "name": "input-0",
      "shape": [2, 4],
      "datatype": "FP32",
      "contents": {
        "fp32_contents": [6.8, 2.8, 4.8, 1.4, 6.0, 3.4, 4.5, 1.6]
      }
    }
  ]
}

ModelInfer API takes input following the ModelInferRequest schema defined in the grpc_predict_v2.proto file. 

grpcurl \
  -vv \
  -plaintext \
  -proto ${PROTO_FILE} \
  -authority ${SERVICE_HOSTNAME} \
  -d @ \
  ${INGRESS_HOST}:${INGRESS_PORT} \
  inference.GRPCInferenceService.ModelInfer \
  <<< $(cat "$INPUT_PATH")

Expected Output

Resolved method descriptor:
// The ModelInfer API performs inference using the specified model. Errors are
// indicated by the google.rpc.Status returned for the request. The OK code
// indicates success and other codes indicate failure.
rpc ModelInfer ( .inference.ModelInferRequest ) returns ( .inference.ModelInferResponse );

Request metadata to send:
(empty)

Response headers received:
content-type: application/grpc
date: Mon, 09 Oct 2023 11:07:26 GMT
grpc-accept-encoding: identity, deflate, gzip
server: istio-envoy
x-envoy-upstream-service-time: 16

Estimated response size: 83 bytes

Response contents:
{
  "model_name": "spark-v2-iris",
  "model_version": null,
  "id": "a187a478-c614-46ce-a7de-2f07871f43f3",
  "parameters": null,
  "outputs": [
    {
      "name": "Species",
      "shape": [
        2
      ],
      "datatype": "BYTES",
      "parameters": null,
      "data": [
        "versicolor",
        "versicolor"
      ]
    },
    {
      "name": "Probability_setosa",
      "shape": [
        2
      ],
      "datatype": "FP64",
      "parameters": null,
      "data": [
        0,
        0
      ]
    },
    {
      "name": "Probability_versicolor",
      "shape": [
        2
      ],
      "datatype": "FP64",
      "parameters": null,
      "data": [
        0.9074074074074074,
        0.9074074074074074
      ]
    },
    {
      "name": "Probability_virginica",
      "shape": [
        2
      ],
      "datatype": "FP64",
      "parameters": null,
      "data": [
        0.09259259259259259,
        0.09259259259259259
      ]
    },
    {
      "name": "Node_Id",
      "shape": [
        2
      ],
      "datatype": "BYTES",
      "parameters": null,
      "data": [
        "6",
        "6"
      ]
    }
  ]
}

Response trailers received:
(empty)
Sent 1 request and received 1 response
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