I experimented with Docker lately. Here are a few commands, notes and issues I resolved while working on Ubuntu 16.04. I'm assuming you have docker installed (sudo apt-get update && apt-get install docker-ce)
Tutorial on the web for "dockerizing" python applications. - https://runnable.com/docker/python/dockerize-your-python-application
Some python example code I made to test with (imgtest.py). This is the code I wanted to place in a docker image. I basically makes a random image and saves it.
import numpy as np
from PIL import Image
import os
img = np.random.randint(0,255,size=(1024,768))
img = img.astype('float')
img = Image.fromarray(img)
img = img.convert('RGB')
img.save('/app/test.jpg')
Here is an example Dockerfile I used. I saved as Dockerfile and placed in same folder as my python script.
FROM python:2
ADD imgtest.py /
RUN pip install numpy
RUN pip install pillow
RUN mkdir /app
CMD ["python","./imgtest.py"]
To build the docker image I moved to the folder where both the Dockerfile and python script reside. And then typed:
sudo docker build .
When building, had to add the DNS to the following (from https://stackoverflow.com/questions/28668180/cant-install-pip-packages-inside-a-docker-container-with-ubuntu). I tried other methods mentioned, but none of them seemed to work except this one. I also commented out the DockerOpts line in /etc/default/docker.
"For Ubuntu users
You need to add new DNS addresses in the docker config
sudo nano /lib/systemd/system/docker.service
Add the dns after ExecStar.
--dns 10.252.252.252 --dns 10.253.253.253
Should look like that:
ExecStart=/usr/bin/dockerd -H fd:// --dns 10.252.252.252 --dns 10.253.253.253
systemctl daemon-reload sudo service docker restart
"
After your build you should be able to list the docker images available using the following command:
sudo docker images
I wanted to run the docker image and make a container. If I ran it with:
sudo docker run -it <image_id>
It would just execute, create the random image output in the container, and then, the container would disappear with no random image output persisted in storage. Instead, I used a bind mount. This bind mount, lets me connect a container's directory to a host's directory. The resulting random image is placed on the docker host.
sudo docker run -d -it -v <host directory>:<container directory> <image_id>
So on my computer it would look something like:
sudo docker run -d -it -v /home/npropes/Desktop:/app 4a823423bca
The random image output should appear on my Desktop.
Additional commands below:
I can see the list of docker containers running or have run by using this command:
sudo docker ps -a
To stop docker containers use these commands:
sudo docker stop <container>
sudo docker kill <container>
To delete a docker container:
sudo docker rm <container>
To delete an docker image:
sudo docker rmi <image>