"Hello, World!" in python

app.py

import os
import datetime
import time
from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello_world():
    target = os.environ.get('TARGET', 'World')
    timestamp = str(datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S'))      
    return timestamp + ' Hello, {}!\n'.format(target)

if __name__ == "__main__":
    app.run(debug=True,host='0.0.0.0',port=int(os.environ.get('PORT', 8080)))

Dockerfile

# Use the official lightweight Python image.
# https://hub.docker.com/_/python
FROM python:3.7-slim

# Allow statements and log messages to immediately appear in the Knative logs
ENV PYTHONUNBUFFERED True

# Copy local code to the container image.
WORKDIR /app
COPY . ./

# Install production dependencies.
RUN pip install Flask gunicorn

# Run the web service on container startup. Here we use the gunicorn
# webserver, with one worker process and 8 threads.
# For environments with multiple CPU cores, increase the number of workers
# to be equal to the cores available.
CMD exec gunicorn --bind :8080 --workers 1 --threads 8 --timeout 0 app:app