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Python 2.7 Hello World App

Last edited by Eric Franz

Ssh to Oakley and then from there to apps-test.awesim.org (webtest04).

We use Software Collections. These versions of python are available:

efranz@webtest04:~$ scl --list | grep python
python27
rh-python35

To load this you can start a new bash session:

efranz@webtest04:~$ scl enable python27 -- bash
efranz@webtest04:~$ python --version
Python 2.7.8

Here is how to get the Passenger Flask python demo working under Open OnDemand. https://github.com/phusion/passenger-python-flask-demo. Ensure that the desired version of python is installed on the webhost.

1. Clone the repo and check out the end result branch:

cd ~/awesim/dev
efranz@webtest04:~/awesim/dev$ git clone git@github.com:phusion/passenger-python-flask-demo.git hellopython
Initialized empty Git repository in /users/PZS0562/efranz/awesim/dev/hellopython/.git/
remote: Counting objects: 18, done.
remote: Compressing objects: 100% (10/10), done.
remote: Total 18 (delta 5), reused 18 (delta 5), pack-reused 0
Receiving objects: 100% (18/18), 5.32 KiB, done.
Resolving deltas: 100% (5/5), done.
efranz@webtest04:~/awesim/dev$ cd hellopython
/users/PZS0562/efranz/awesim/dev/hellopython
efranz@webtest04:~/awesim/dev/hellopython (master)$ git checkout end_result
Branch end_result set up to track remote branch end_result from origin.
Switched to a new branch 'end_result'
  • notice passenger_wsgi.py imports the app.py file; Passenger will load passenger_wsgi.py first

2. Create a .pip directory that will hold dependencies for this app, and install dependencies here:

efranz@webtest04:~/awesim/dev/hellopython (end_result)$ mkdir .pip
efranz@webtest04:~/awesim/dev/hellopython (end_result)$ export PYTHONPATH=./.pip:$PYTHONPATH
efranz@webtest04:~/awesim/dev/hellopython (end_result)$ pip install -t .pip flask
You are using pip version 7.1.0, however version 9.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
Collecting flask
  Using cached Flask-0.12-py2.py3-none-any.whl
Collecting click>=2.0 (from flask)
  Using cached click-6.7-py2.py3-none-any.whl
Collecting itsdangerous>=0.21 (from flask)
Collecting Werkzeug>=0.7 (from flask)
  Using cached Werkzeug-0.11.15-py2.py3-none-any.whl
Collecting Jinja2>=2.4 (from flask)
  Using cached Jinja2-2.9.5-py2.py3-none-any.whl
Collecting MarkupSafe>=0.23 (from Jinja2>=2.4->flask)
Installing collected packages: click, itsdangerous, Werkzeug, MarkupSafe, Jinja2, flask
Successfully installed Jinja2-2.6 MarkupSafe-0.11 Werkzeug-0.8.3 click flask itsdangerous
efranz@webtest04:~/awesim/dev/hellopython (end_result)$ python
Python 2.7.8 (default, Aug  4 2016, 09:29:33)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-9)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import flask
>>>

The idea of using pip this way came from https://www.zoomeranalytics.com/blog/pip-install-t

  • note: seeing in the comment thread under that blog article, this might not be the best approach

3. Add bin/python command which will be used to setup the environment when Passenger launches the app

NGINX with Passenger is configured to execute $APPROOT/bin/python if this exists, so we can add environment modifications here. Following the example https://github.com/OSC/nginx_stage/blob/cc1398ed35214ed6bd774ffee93ad679e5f01cb0/bin/ood_ruby.example

Add these contents to bin/python and make it executable (chmod 755):

#!/bin/bash

# following example https://github.com/OSC/nginx_stage/blob/cc1398ed35214ed6bd774ffee93ad679e5f01cb0/bin/ood_ruby.example


# python27
SCL_PKGS=${SCL_PKGS:-"nginx16 rh-passenger40 rh-ruby22 nodejs010 git19 python27"}

# python35
# SCL_PKGS=${SCL_PKGS:-"nginx16 rh-passenger40 rh-ruby22 nodejs010 git19 rh-python35"}

SCL_SOURCE=$(command -v scl_source)
[[ ${SCL_SOURCE}  ]] && source ${SCL_SOURCE} enable ${SCL_PKGS}


# $PWD is always application root in a Passenger App
export PYTHONPATH=$PWD/.pip:$PYTHONPATH

exec /bin/env python "$@"
  • this loads environment with the SCL packages AND adds $APPROOT/.pip to the PYTHONPATH

4. Access app URL to launch

Go to https://apps-test.awesim.org/pun/dev/hellopython or go to Develop->Sandbox Apps on the dashboard to launch app