This document provides an introduction to containerization using Docker. It explains that Docker packages applications and dependencies into containers that are lighter than virtual machines. It then demonstrates how to Dockerize a Python web scraping application by creating a Dockerfile to build an image, run a container from the image locally, push the image to a registry, and run the container on another host that pulls from the registry. References for further Docker learning are also included.

1. Dockerize Your Projects
A Brief Introduction to Containerization
Sawood Alam <@ibnesayeed>
Old Dominion University, Norfolk, Virginia - 23529 (USA)

2. Docker
● Application container
● Packages dependencies
● Isolates applications
● Lighter than a virtual machine
● Open-source Host OS
Host OS
Docker Engine
Bins/Libs
App B
Bins/Libs
App A
Container

3. Dockerization
Dockerfile ImageBuild Run Container

4. Example
#!/usr/bin/env python
import sys
import requests
from bs4 import BeautifulSoup
r = requests.get(sys.argv[-1])
data = r.text
soup = BeautifulSoup(data)
for link in soup.find_all("a"):
print(link.get("href"))
FROM python
LABEL maintainer="Sawood Alam <@ibnesayeed>"
RUN pip install beautifulsoup4
RUN pip install requests
COPY main.py /app/
WORKDIR /app
RUN chmod a+x main.py
ENTRYPOINT ["./main.py"]
main.py Dockerfile

5. Try It
me@thishost$ ls
>> Dockerfile main.py
# Build an image from the Dockerfile (change "ibnesayeed" with your Docker ID)
me@thishost$ docker image build -t ibnesayeed/urlextractor .
>> Layered docker images...
# Run a container from the locally built image
me@thishost$ docker container run ibnesayeed/urlextractor https://odu.edu/compsci
>> Extracted links…
# Push the image to the registry
me@thishost$ docker image push ibnesayeed/urlextractor
# Log in to a different host
me@thishost$ ssh you@otherhost
# Run a container on the other host using the image in the registry
you@otherhost$ docker container run ibnesayeed/urlextractor https://odu.edu/compsci
>> Pull the image from the registry (if not cached already)
>> Extracted links...

6. References
● https://www.docker.com/
● https://docs.docker.com/
● https://training.docker.com/
● http://training.play-with-docker.com/
● https://hub.docker.com/
● https://hub.docker.com/r/ibnesayeed/urlextractor/
● https://gist.github.com/ibnesayeed/b4b069b8007f68be91a179a099e35d71