#python-container-experiment

If you ever wonder how to run various python versions in your docker containers and execute your script by them, you find answer here

There are Docker files named accordingly to python version, eg. Dockerfile.py3 will create container with python3 and with simlink pytho3 -> python

In the Docker file, you can specify which python version and which python libraries and tools you want to be installed in your image, e.g. I want to have installed python3 python3-numpy python3-matplotlib

One of the trick with such container as just python language, which is doing nothing after start is to keep it alive or in kind of infinite loop. One can done it with command:

• CMD exec /bin/bash -c "trap : TERM INT; sleep infinity & wait"

It is importatnt to put selinux into permisive mode:

• getenforce - tells you your selinux status
• sudo setenforce 0 - switch selinux to the permissive mode

How to build

• docker build -t python3:f25 -f Dockerfile.py3 . - to build image with latest Fedora 25 python3
• docker build -t python2:f25 -f Dockerfile.py2 . - to build image with python2
• docker build -t python33:f25 -f Dockerfile.py3.3 . - to build image with python 3.3
• docker build -t python34:f25 -f Dockerfile.py3.4 . - to build image with python 3.4

How to run the containers

• docker run -v /home/mkocka/work/:/work --name py3 python3:f25 &
• docker run -v /home/mkocka/work/:/work --name py2 python2:f25 &
• docker run -v /home/mkocka/work/:/work --name py33 python33:f25 &
• docker run -v /home/mkocka/work/:/work --name py34 python34:f25 &

How to execute your script in your container

Using -v /home/mkocka/work/:/work You created a bind mount and you just need to have your script in mounted folder: /home/mkocka/work/ in my case simple app.py which only print the python version.

• docker exec -it py2 python /work/app.py - app.py executed by default python which is in Fedora 25 python version 2.7
• docker exec -it py3 python /work/app.py - app.py executed by latest python in Fedora 25 which is python version 3.5
• docker exec -it py33 python /work/app.py - app.py executed by python 3.3
• docker exec -it py34 python /work/app.py - app.py executed by python 3.4

In my case, the output looks like this:

[mkocka@TheDude python-container-experiment]$ docker exec -it py2 python /work/app.py
2.7.13(default, Jan 12 2017, 17:59:37)
[GCC 6.3.1 20161221 (Red Hat 6.3.1-1)]
[mkocka@TheDude python-container-experiment]$ docker exec -it py3 python /work/app.py
3.5.2(default, Sep 14 2016, 11:28:32)
[GCC 6.2.1 20160901 (Red Hat 6.2.1-1)]
[mkocka@TheDude python-container-experiment]$ docker exec -it py34 python /work/app.py
3.4.5(default, Oct 21 2016, 22:32:58)
[GCC 6.2.1 20160916 (Red Hat 6.2.1-2)]
[mkocka@TheDude python-container-experiment]$ docker exec -it py33 python /work/app.py
3.3.6(default, Oct 21 2016, 22:30:00)
[GCC 6.2.1 20160916 (Red Hat 6.2.1-2)]

How to execute more complicated script with plots

TBD