Create APIs that can perform arbitrary tasks like training or fine-tuning a model.


# train_iris.py
import os
import boto3
import pickle
from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
from sklearn.linear_model import LogisticRegression
class Task:
def __call__(self, config):
# get the iris flower dataset
iris = load_iris()
data, labels = iris.data, iris.target
training_data, test_data, training_labels, test_labels = train_test_split(data, labels)
print("loaded dataset")
# train the model
model = LogisticRegression(solver="lbfgs", multi_class="multinomial", max_iter=1000)
model.fit(training_data, training_labels)
accuracy = model.score(test_data, test_labels)
print("model trained; accuracy: {:.2f}".format(accuracy))
# upload the model
dest_dir = config["dest_s3_dir"]
bucket, key = dest_dir.replace("s3://", "").split("/", 1)
pickle.dump(model, open("model.pkl", "wb"))
s3 = boto3.client("s3")
s3.upload_file("model.pkl", bucket, os.path.join(key, "model.pkl"))
print(f"model uploaded to {dest_dir}/model.pkl")
# requirements.txt
# cortex.yaml
- name: train-iris
kind: TaskAPI
path: train_iris.py


$ cortex deploy


$ cortex get train-iris
# > endpoint: http://***.elb.us-west-2.amazonaws.com/train-iris

Submit a job

You can submit a job by making a POST request to the Task API's endpoint.

Using curl:

$ export TASK_API_ENDPOINT=<TASK_API_ENDPOINT> # e.g. export TASK_API_ENDPOINT=https://***.elb.us-west-2.amazonaws.com/train-iris
$ export DEST_S3_DIR=<YOUR_S3_DIRECTORY> # e.g. export DEST_S3_DIR=s3://my-bucket/dir
-X POST -H "Content-Type: application/json" \
-d "{\"config\": {\"dest_s3_dir\": \"$DEST_S3_DIR\"}}"
# > {"job_id":"69b183ed6bdf3e9b","api_name":"train-iris",...}

Or, using Python requests:

import cortex
import requests
cx = cortex.client("aws") # "aws" is the name of the Cortex environment used in this example
task_endpoint = cx.get_api("train-iris")["endpoint"]
dest_s3_dir = # S3 directory where the model will be uploaded, e.g. "s3://my-bucket/dir"
job_spec = {
"config": {
"dest_s3_dir": dest_s3_dir
response = requests.post(task_endpoint, json=job_spec)
# > {"job_id":"69b183ed6bdf3e9b","api_name":"train-iris",...}

Monitor the job

$ cortex get train-iris 69b183ed6bdf3e9b

View the results

Once the job is complete, you should be able to find the trained model in the directory you've specified.


$ cortex delete train-iris