Python Docker image
This repository contains the source for building various versions of
the Python application as a reproducible Docker image using
Users can choose between RHEL and CentOS based builder images.
The resulting image can be run using Docker.
For RHEL based image
$ s2i build https://github.com/sclorg/s2i-python-container.git --context-dir=3.4/test/setup-test-app/ rhscl/python-34-rhel7 python-sample-app $ docker run -p 8080:8080 python-sample-app
For CentOS based image
$ s2i build https://github.com/sclorg/s2i-python-container.git --context-dir=3.4/test/setup-test-app/ centos/python-34-centos7 python-sample-app $ docker run -p 8080:8080 python-sample-app
Accessing the application:
$ curl 127.0.0.1:8080
CentOS based Dockerfile.
RHEL based Dockerfile. In order to perform build or test actions on this
Dockerfile you need to run the action on a properly subscribed RHEL machine.
This folder contains scripts that are run by S2I:
Used to install the sources into the location where the application
will be run and prepare the application for deployment (eg. installing
This script is responsible for running the application by using the
application web server.
This script prints the usage of this image.
This folder contains a file with commonly used modules.
This folder contains a S2I
test framework with a simple server.
To set these environment variables, you can place them as a key value pair into a
file inside your source code repository.
Used to run the application from a script file.
This should be a path to a script file (defaults to
app.shunless set to null) that will be
run to start the application.
Used to run the application from a Python script.
This should be a path to a Python file (defaults to
app.pyunless set to null) that will be
passed to the Python interpreter to start the application.
Used to run the application with Gunicorn, as documented
This variable specifies a WSGI callable with the pattern
MODULE_NAMEis the full dotted path
of a module, and
VARIABLE_NAMErefers to a WSGI callable inside the
Gunicorn will look for a WSGI callable named
applicationif not specified.
APP_MODULEis not provided, the
runscript will look for a
file in your project and use it if it exists.
setup.pyfor installing the application, the
can be read from there. For an example, see
This variable can be used to specify a sub-directory in which the application to be run is contained.
The directory pointed to by this variable needs to contain
wsgi.py(for Gunicorn) or
APP_HOMEis not provided, the
runscripts will use the application's root
Path to a valid Python file with a
Gunicorn configuration file.
Set this variable to a non-empty value to inhibit the execution of
'manage.py collectstatic' during the build. This only affects Django projects.
Set this variable to a non-empty value to inhibit the execution of 'manage.py migrate'
when the produced image is run. This only affects Django projects.
Set this variable to use a custom index URL or mirror to download required packages
during build process. This only affects packages listed in requirements.txt.
Set this variable to a non-empty value to have the 'pip' program be upgraded
to the most recent version before any Python packages are installed. If not
set it will use whatever the default version is included by the platform
for the Python version being used.
Set this to change the default setting for the number of
default, this is set to the number of available cores times 2.
Source repository layout
You do not need to change anything in your existing Python project's repository.
However, if these files exist they will affect the behavior of the build process:
List of dependencies to be installed with
pip. The format is documented
Configures various aspects of the project, including installation of
dependencies, as documented
For most projects, it is sufficient to simply use
The Docker image produced by s2i-python executes your project in one of the
following ways, in precedence order:
The Gunicorn WSGI HTTP server is used to serve your application in the case that it
is installed. It can be installed by listing it either in the
file or in the
install_requiressection of the
If a file named
wsgi.pyis present in your repository, it will be used as
the entry point to your application. This can be overridden with the
This file is present in Django projects by default.
If you have both Django and Gunicorn in your requirements, your Django project
will automatically be served using Gunicorn.
Django development server
If you have Django in your requirements but don't have Gunicorn, then your
application will be served using Django's development web server. However, this is not
recommended for production environments.
This would be used where you provide a Python code file for running you
application. It will be used in the case where you specify a path to a
Python script via the
APP_FILEenvironment variable, defaulting to a
app.pyif it exists. The script is passed to a regular
Python interpreter to launch your application.
Application script file
This is the most general way of executing your application. It will be
used in the case where you specify a path to an executable script file
APP_SCRIPTenvironment variable, defaulting to a file named
app.shif it exists. The script is executed directly to launch your
If you are using Django, hot deploy will work out of the box.
To enable hot deploy while using Gunicorn, make sure you have a Gunicorn
configuration file inside your repository with the
option set to
true. Make sure to specify your config via the
To change your source code in running container, use Docker's
docker exec -it <CONTAINER_ID> /bin/bash
After you enter into the running container, your current directory is set
/opt/app-root/src, where the source code is located.