Introduction to the Dockerfile Part II

Intoduction to the Dockerfile for beginner

source image : deploybot.com

Create Dockerfile

vim Dockerfile

Dockerfile content:

# Use an official Python runtime as a parent image
FROM python:2.7-slim
# Set the working directory to /app
WORKDIR /app
# Copy the current directory contents into the container at /app
ADD . /app
# Install any needed packages specified in requirements.txt
RUN pip install — trusted-host pypi.python.org -r requirements.txt
# Make port 80 available to the world outside this container
EXPOSE 80
# Define environment variable
ENV NAME World
# Run app.py when the container launches
CMD ["python", "app.py"]

Create requirements.txt file

Flask
Redis

Create app.py file

from flask import Flask
from redis import Redis, RedisError
import os
import socket
# Connect to Redis
redis = Redis(host="redis", db=0, socket_connect_timeout=2, socket_timeout=2)
app = Flask(__name__)
@app.route("/")
def hello():
 try:
 visits = redis.incr("counter")
 except RedisError:
 visits = "<i>cannot connect to Redis, counter disabled</i>"
html = "<h3>Hello {name}!</h3>" \
 "<b>Hostname:</b> {hostname}<br/>" \
 "<b>Visits:</b> {visits}"
 return html.format(name=os.getenv("NAME", "world"), hostname=socket.gethostname(), visits=visits)
if __name__ == "__main__":
 app.run(host=’0.0.0.0', port=80)

Build image from Dockerfile

sudo docker build -t friendlyhello .

See image friendlyhello

sudo docker image ls

Run image friendlyhello

sudo docker run -d -p 4000:80 friendlyhello

See container :

sudo docker container ls

Test app using curl

curl http://localhost:4000

Test app