Python 3.6 container image =================== This container image includes Python 3.6 as a [S2I](https://github.com/openshift/source-to-image) base image for your Python 3.6 applications. Users can choose between RHEL and CentOS based builder images. The RHEL image is available in the [Red Hat Container Catalog](https://access.redhat.com/containers/#/registry.access.redhat.com/rhscl/python-36-rhel7) as registry.access.redhat.com/rhscl/python-36-rhel7. The CentOS image is then available on [Docker Hub](https://hub.docker.com/r/centos/python-36-centos7/) as centos/python-36-centos7. The resulting image can be run using [Docker](http://docker.io). Description ----------- Python 3.6 available as container is a base platform for building and running various Python 3.6 applications and frameworks. Python is an easy to learn, powerful programming language. It has efficient high-level data structures and a simple but effective approach to object-oriented programming. Python's elegant syntax and dynamic typing, together with its interpreted nature, make it an ideal language for scripting and rapid application development in many areas on most platforms. This container image includes an npm utility, so users can use it to install JavaScript modules for their web applications. There is no guarantee for any specific npm or nodejs version, that is included in the image; those versions can be changed anytime and the nodejs itself is included just to make the npm work. Usage --------------------- To build a simple [python-sample-app](https://github.com/sclorg/s2i-python-container/tree/master/3.6/test/setup-test-app) application using standalone [S2I](https://github.com/openshift/source-to-image) and then run the resulting image with [Docker](http://docker.io) execute: * **For RHEL based image** ``` $ s2i build https://github.com/sclorg/s2i-python-container.git --context-dir=3.6/test/setup-test-app/ rhscl/python-36-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=3.6/test/setup-test-app/ centos/python-36-centos7 python-sample-app $ docker run -p 8080:8080 python-sample-app ``` **Accessing the application:** ``` $ curl 127.0.0.1:8080 ``` Environment variables --------------------- To set these environment variables, you can place them as a key value pair into a `.s2i/environment` file inside your source code repository. * **APP_SCRIPT** Used to run the application from a script file. This should be a path to a script file (defaults to `app.sh` unless set to null) that will be run to start the application. * **APP_FILE** Used to run the application from a Python script. This should be a path to a Python file (defaults to `app.py` unless set to null) that will be passed to the Python interpreter to start the application. * **APP_MODULE** Used to run the application with Gunicorn, as documented [here](http://docs.gunicorn.org/en/latest/run.html#gunicorn). This variable specifies a WSGI callable with the pattern `MODULE_NAME:VARIABLE_NAME`, where `MODULE_NAME` is the full dotted path of a module, and `VARIABLE_NAME` refers to a WSGI callable inside the specified module. Gunicorn will look for a WSGI callable named `application` if not specified. If `APP_MODULE` is not provided, the `run` script will look for a `wsgi.py` file in your project and use it if it exists. If using `setup.py` for installing the application, the `MODULE_NAME` part can be read from there. For an example, see [setup-test-app](https://github.com/sclorg/s2i-python-container/tree/master/3.6/test/setup-test-app). * **APP_HOME** 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 `manage.py` (for Django). If `APP_HOME` is not provided, the `assemble` and `run` scripts will use the application's root directory. * **APP_CONFIG** Path to a valid Python file with a [Gunicorn configuration](http://docs.gunicorn.org/en/latest/configure.html#configuration-file) file. * **DISABLE_MIGRATE** 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. See "Handling Database Migrations" section of [Django blogpost on OpenShift blog]( https://blog.openshift.com/migrating-django-applications-openshift-3/) on suggestions how/when to run DB migrations in OpenShift environment. Most importantly, note that running DB migrations from two or more pods might corrupt your database. * **DISABLE_COLLECTSTATIC** Set this variable to a non-empty value to inhibit the execution of 'manage.py collectstatic' during the build. This only affects Django projects. * **DISABLE_SETUP_PY_PROCESSING** Set this to a non-empty value to skip processing of setup.py script if you use `-e .` in requirements.txt to trigger its processing or you don't want your application to be installed into site-packages directory. * **ENABLE_PIPENV** Set this variable to use [Pipenv](https://github.com/kennethreitz/pipenv), the higher-level Python packaging tool, to manage dependencies of the application. This should be used only if your project contains properly formated Pipfile and Pipfile.lock. * **PIP_INDEX_URL** 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. Pipenv ignores this variable. * **UPGRADE_PIP_TO_LATEST** Set this variable to a non-empty value to have the 'pip' program and related python packages (setuptools and wheel) 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. * **WEB_CONCURRENCY** Set this to change the default setting for the number of [workers](http://docs.gunicorn.org/en/stable/settings.html#workers). By default, this is set to the number of available cores times 2, capped at 12. 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: * **requirements.txt** List of dependencies to be installed with `pip`. The format is documented [here](https://pip.pypa.io/en/latest/user_guide.html#requirements-files). * **Pipfile** The replacement for requirements.txt, project is currently under active design and development, as documented [here](https://github.com/pypa/pipfile). Set `ENABLE_PIPENV` environment variable to true in order to process this file. * **setup.py** Configures various aspects of the project, including installation of dependencies, as documented [here](https://packaging.python.org/en/latest/distributing.html#setup-py). For most projects, it is sufficient to simply use `requirements.txt` or `Pipfile`. Set `DISABLE_SETUP_PY_PROCESSING` environment variable to true in order to skip processing of this file. Run strategies -------------- The container image produced by s2i-python executes your project in one of the following ways, in precedence order: * **Gunicorn** 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 `requirements.txt` file or in the `install_requires` section of the `setup.py` file. If a file named `wsgi.py` is present in your repository, it will be used as the entry point to your application. This can be overridden with the environment variable `APP_MODULE`. 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. * **Python script** 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_FILE` environment variable, defaulting to a file named `app.py` if 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 via the `APP_SCRIPT` environment variable, defaulting to a file named `app.sh` if it exists. The script is executed directly to launch your application. Hot deploy --------------------- 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 [`reload`](https://gunicorn-docs.readthedocs.org/en/latest/settings.html#reload) option set to `true`. Make sure to specify your config via the `APP_CONFIG` environment variable. To change your source code in running container, use Docker's [exec](https://docs.docker.com/reference/commandline/exec/) command: ``` docker exec -it /bin/bash ``` After you enter into the running container, your current directory is set to `/opt/app-root/src`, where the source code is located. See also -------- Dockerfile and other sources are available on https://github.com/sclorg/s2i-python-container. In that repository you also can find another versions of Python environment Dockerfiles. Dockerfile for CentOS is called Dockerfile, Dockerfile for RHEL is called Dockerfile.rhel7.