Package a Model Image from a Reusable Base Image

Overview

This document shows the best practice to reuse a base image and build the model image on top of the base image. Using the base image has some benefits:

If the way you load and use models is the same, these models can share the same base image
If you just want to update the model file, a base image can speed up the building process

The idea is that you write a general model serving code and assume the model file is placed under a certain path. As a model is ready, use docker build to generate the model image from the base image along with the model files.

To prepare the base image, there are two methods

Build the base image by Language Wrapper
Use pre-packaged server as Base Image

Prerequisites

Docker: https://www.docker.com/products/docker-desktop

Build the Base Image by Language Wrapper

Here, we use Tensorflow 2 as a simple showcase. The code is under Github.

Build the Base Image

Write a general model serving code Model.py.

import tensorflow as tf

class Model:
    def __init__(self):
        self.loaded = False

    def load(self):
        self._model = tf.keras.models.load_model('model')
        self.loaded = True

    def predict(self, X, feature_names=None, meta=None):
        if not self.loaded:
            self.load()
        output = self._model.predict(X)
        return output

Create a requirements.txt file and write down all required packages.
```
seldon-core==1.6.0
tensorflow==2.3.1
```

Create a Dockerfile with the following content.

FROM python:3.7-slim
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
EXPOSE 9000

# Define environment variable
ENV MODEL_NAME Model
ENV SERVICE_TYPE MODEL
ENV PERSISTENCE 0

CMD exec seldon-core-microservice $MODEL_NAME --service-type $SERVICE_TYPE --persistence $PERSISTENCE --access-log

Build the base image.

docker build . -t tensorflow2-prepackage

Build the Model Image

Based on our previous base image, whenever you have a model outputted by
```
model.save(export_path)
```
You can use this base image to build your model deployment image.
First, create a Dockerfile.
```
FROM tensorflow2-prepackage
COPY export_path model
```
(Please replace the export_path to your path)

This means you copy your model files into the path that you pre-defined in the base image code.

Then, you can build the model deployment image.

docker build . -t tensorflow2-prepackage-model

Verify the Model Image

To verify the image, you can run it.

docker run -p 5000:5000 --rm tensorflow2-prepackage-model

And send a post request by the following format.
```
curl -X POST localhost:5000/api/v1.0/predictions \
    -H 'Content-Type: application/json' \
    -d '{ "data": {"ndarray": [${INPUT_DATA}] } }'
```
The ${INPUT_DATA} is the data that you can feed into the deployed model for prediction.

The dimension of input data must be the same as the model's input shape.

For example, if we create our model with a specified input_shape=(4,) by the following definition.

model = tf.keras.models.Sequential([
    keras.layers.Dense(64, activation='relu', input_shape=(4,)),
    ...
    ...
])

Then, we can send a post request that ${INPUT_DATA} with shape 4.

curl -X POST localhost:5000/api/v1.0/predictions \
    -H 'Content-Type: application/json' \
    -d '{ "data": {"ndarray": [[5.1, 3.3, 1.7, 0.5]] } }'

Or if we create our model with a specified input_shape=(2,2) by the following definition.

model = tf.keras.models.Sequential([
    keras.layers.Dense(64, activation='relu', input_shape=(2,2)),
    ...
    ...
])

Then, we can also send a post request that ${INPUT_DATA} with shape (2,2).

curl -X POST localhost:5000/api/v1.0/predictions \
    -H 'Content-Type: application/json' \
    -d '{ "data": {"ndarray": [[[5.1, 3.3], [1.7, 0.5]]] } }'

After sending the post request, we can obtain the response output in the following format.
```
{"data":{"names":[],"ndarray":[${PREDICTION_RESULT}]},"meta":{}}
```
The ${PREDICTION_RESULT} is a list to represent the prediction value.
For example, the following output shows three prediction values in each class.
```
{"data":{"names":[],"ndarray":[[3.093,-0.519,-8.918]]},"meta":{}}
```
After verifying your model deployment image, now you can use this image in the PrimeHub model deployment feature.

Use Pre-packaged Server as Base Image

Here, we use the tensorflow2 pre-packaged server as an example.

Build the Model Image

First, prepare the model files. We can use the example model in github. The model files can be found in tensorflow2/example_model/mnist.
```
git clone git@github.com:InfuseAI/primehub-seldon-servers.git
cd primehub-seldon-servers
```

Then, create a Dockerfile, in which we copy the model files into the /mnt/models and tell the pre-packaged server to use this path as model_uri.

FROM infuseai/tensorflow2-prepackaged:v0.1.0
COPY tensorflow2/example_model/mnist /mnt/models
ENV PREDICTIVE_UNIT_PARAMETERS='[{"name":"model_uri","value":"/mnt/models","type":"STRING"}]'

Build the image from the Dockerfile.

docker build . -t tensorflow2-prepackage-model

Verify the Model Image

Run the model server.

docker run -p 9000:9000 --rm tensorflow2-prepackage-model

Verify the model server.

curl -X POST http://localhost:9000/api/v1.0/predictions \
    -H 'Content-Type: application/json' \
    -d '{ "data": {"ndarray": [[[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.32941176470588235, 0.7254901960784313, 0.6235294117647059, 0.592156862745098, 0.23529411764705882, 0.1411764705882353, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.8705882352941177, 0.996078431372549, 0.996078431372549, 0.996078431372549, 0.996078431372549, 0.9450980392156862, 0.7764705882352941, 0.7764705882352941, 0.7764705882352941, 0.7764705882352941, 0.7764705882352941, 0.7764705882352941, 0.7764705882352941, 0.7764705882352941, 0.6666666666666666, 0.20392156862745098, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.2627450980392157, 0.4470588235294118, 0.2823529411764706, 0.4470588235294118, 0.6392156862745098, 0.8901960784313725, 0.996078431372549, 0.8823529411764706, 0.996078431372549, 0.996078431372549, 0.996078431372549, 0.9803921568627451, 0.8980392156862745, 0.996078431372549, 0.996078431372549, 0.5490196078431373, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.06666666666666667, 0.25882352941176473, 0.054901960784313725, 0.2627450980392157, 0.2627450980392157, 0.2627450980392157, 0.23137254901960785, 0.08235294117647059, 0.9254901960784314, 0.996078431372549, 0.41568627450980394, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.3254901960784314, 0.9921568627450981, 0.8196078431372549, 0.07058823529411765, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.08627450980392157, 0.9137254901960784, 1.0, 0.3254901960784314, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.5058823529411764, 0.996078431372549, 0.9333333333333333, 0.17254901960784313, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.23137254901960785, 0.9764705882352941, 0.996078431372549, 0.24313725490196078, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.5215686274509804, 0.996078431372549, 0.7333333333333333, 0.0196078431372549, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.03529411764705882, 0.803921568627451, 0.9725490196078431, 0.22745098039215686, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.49411764705882355, 0.996078431372549, 0.7137254901960784, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.29411764705882354, 0.984313725490196, 0.9411764705882353, 0.2235294117647059, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.07450980392156863, 0.8666666666666667, 0.996078431372549, 0.6509803921568628, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.011764705882352941, 0.796078431372549, 0.996078431372549, 0.8588235294117647, 0.13725490196078433, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.14901960784313725, 0.996078431372549, 0.996078431372549, 0.30196078431372547, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.12156862745098039, 0.8784313725490196, 0.996078431372549, 0.45098039215686275, 0.00392156862745098, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.5215686274509804, 0.996078431372549, 0.996078431372549, 0.20392156862745098, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.23921568627450981, 0.9490196078431372, 0.996078431372549, 0.996078431372549, 0.20392156862745098, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.4745098039215686, 0.996078431372549, 0.996078431372549, 0.8588235294117647, 0.1568627450980392, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.4745098039215686, 0.996078431372549, 0.8117647058823529, 0.07058823529411765, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]]] } }'

The response would be like

{"data":{"names":[],"ndarray":[[2.2179543179845496e-07,1.2331367038598273e-08,2.5685820219223388e-05,0.0001267448824364692,3.67312957827437e-10,8.802280717645772e-07,1.7313700820253963e-11,0.9998445510864258,5.112406711305084e-07,1.4923076605555252e-06]]},"meta":{}}

Share Your Base Image

Share your base image by pushing it to a docker registry.
Therefore, others can re-use the model serving code again. They can share the same base image and build a model image by docker.