242 lines
9.9 KiB
Markdown
242 lines
9.9 KiB
Markdown
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 <CONTAINER_ID> /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.
|