James Gregson's Website

Oct 25, 2018

Create Docker Image

This process follows this link . First update apt and install docker.io

$ sudo apt-get update
$ sudo apt install docker.io

Next start the service and enable it at boot time:

$ sudo systemctl start docker
$ sudo systemctl enable docker

Finally add your current user to the docker group:

$ sudo usermod -a -G docker $USER

and log out of your account and back in.

Create Dockerfile

Create a blank Dockerfile

$ touch Dockerfile

and then edit it to look like the following:

# start with ubuntu
FROM ubuntu:16.04

# update the software repository
RUN apt-get update
RUN apt-get install -y python3-dev

# add user appuser and switch to it
RUN useradd -ms /bin/bash appuser
USER appuser
WORKDIR /home/appuser

# copy over a test message and python
# script to print it to the screen
COPY data/ ./data/
COPY print_message.py .

# run the script at container startup
CMD ["python3", "print_message.py"]

Next make a directory to share with the image and put a simple message file into it.

$ mkdir data
$ echo "Hello from docker" > data/message.txt

Then create a python script to print the message:

if __name__ == '__main__':

    with open('data/message.txt') as f:
        data = f.read()
        print( data )

Build the image and run it:

$ docker build -t test_image
$ docker run -it test_image
Hello from docker

And that's all there is to it.