Preface
I have been using OpenShift for a few months now and have to say that
I still love it. I've sampled most of the other PaaS solutions and
feel most comfortable with OpenShift. One of the features I enjoy most
in the service is the "do-it-yourself" application. With this, you can
run just about anything in a "minimal-hassle", scalable environment.
I created a quickstart a few weeks ago that had Django running on
Python 2.7 in "DIY" mode. This will use some of that, but be a more
"step-by-step" approach for newcomers. This example will use the
Flask micro-framework as well as the uWSGI application container for a true, production ready environment.
Diving In
The first thing you will need to do is get an
OpenShift account (it's free).
Client Tools
Install the OpenShift client tools:
gem install rhc
** See
here if you have trouble getting the tools installed.
Application Setup
Once you have the toolchain setup, we will create the application
environment in OpenShift. For this example, we will name our
application "py27".
rhc app create py27 diy-0.1
You will see something similar to:
Creating application: py27 in ehazlett
Now your new domain name is being propagated worldwide (this might take a minute)...
Confirming application 'py27' is available: Success!
py27 published: http://py27-ehazlett.rhcloud.com/
git url: ssh://uuid1234567890@py27-ehazlett.rhcloud.com/~/git/py27.git/
Disclaimer: This is an experimental cartridge that provides a way to try unsupported languages, frameworks, and middleware on Openshift.
You can view the bootstrapped application at
http://py27-[namepsace].rhcloud.com
Python 2.7
Now that the application environment is created, we will build and
install the latest Python 2.7.x release. To do that, we will first need
to get the application SSH credentials.
Run the following to show your application config (enter your account password when prompted):
rhc app show -a py27
You should see something similar to this:
Application Info
================
py27
Framework: diy-0.1
Creation: 2012-05-15T22:54:09-04:00
UUID: 1qaz2wsx3edc4rfv
Git URL: ssh://1qaz2wsx3edc4rfv@py27-ehazlett.rhcloud.com/~/git/py27.git/
Public URL: http://py27-ehazlett.rhcloud.com/
Embedded:
None
Log into your OpenShift application using the SSH credentials from above (in the Git URL line):
ssh 1qaz2wsx3edc4rfv@py27-[username].rhcloud.com
We will build everything in the OpenShift application tmp directory.
Navigate into the "tmp" directory:
cd $OPENSHIFT_TMP_DIR
Download the latest Python 2.7.x release:
wget http://python.org/ftp/python/2.7.3/Python-2.7.3.tar.bz2
Extract:
tar jxf Python-2.7.3.tar.bz2
Configure (to put the custom Python into the OpenShift runtime dir):
cd Python-2.7.3
./configure --prefix=$OPENSHIFT_DATA_DIR
Make and install:
make install
You can now check that Python was successfully installed:
$OPENSHIFT_DATA_DIR/bin/python -V
You should get
Python 2.7.3
Supporting Tools
We now have Python installed, but we can't do much. Part of the common Python toolchain is PIP for Python package management.
Setuptools
Change into the OpenShift "tmp" directory:
cd $OPENSHIFT_TMP_DIR
Download and install setuptools:
wget http://pypi.python.org/packages/source/s/setuptools/setuptools-0.6c11.tar.gz
tar zxf setuptools-0.6c11.tar.gz
cd setuptools-0.6c11
Install:
$OPENSHIFT_DATA_DIR/bin/python setup.py install
PIP
Change into the OpenShift "tmp" directory:
cd $OPENSHIFT_TMP_DIR
Download and install setuptools:
wget http://pypi.python.org/packages/source/p/pip/pip-1.1.tar.gz
tar zxf pip-1.1.tar.gz
cd pip-1.1
Install:
$OPENSHIFT_DATA_DIR/bin/python setup.py install
Application
Okay, so now we have all of the parts needed to run the app. We now
need to create the Flask application and configure OpenShift so that it
knows how to start and stop it.
First we will create the Flask application. Logout of your OpenShift
environment and navigate into the Git repository that was created for
your app.
Create a file named
application.py in the repo, for example - in the
diy folder:
??? README
??? diy
? ??? index.html
? ??? testrubyserver.rb
? ??? application.py
??? misc
BTW, the
index.html and
testrubyserver.rb are not longer necessary and can be removed anytime.
Edit
application.py with the following:
from flask import Flask
import platform
application = Flask(__name__)
@application.route("/")
def index():
return 'Hello from Flask'
@application.route("/info")
def info():
return platform.python_version()
Create a
requirements.txt in the root application directory with the following:
uWSGI==1.2.3
Flask==0.8
Directory structure should look like:
??? README
??? diy
? ??? application.py
? ??? index.html
? ??? testrubyserver.rb
??? misc
??? requirements.txt
Hooks
We will now create the hooks that are needed for deployment as well
as for starting and stopping the application. In your application Git
repository, there is a hidden directory called ".openshift" that
contains stubs for the action hooks. We will be editing these.
Edit
.openshift/action_hooks/build to have the following:
$OPENSHIFT_DATA_DIR/bin/pip install --use-mirrors -r $OPENSHIFT_REPO_DIR/requirements.txt
Edit
.openshift/action_hooks/start to have the following:
$OPENSHIFT_DATA_DIR/bin/uwsgi -s $OPENSHIFT_DIY_IP:$OPENSHIFT_DIY_PORT --socket-protocol http --pp $OPENSHIFT_REPO_DIR/diy --module application -d $OPENSHIFT_DIY_LOG_DIR/app.log --pidfile $OPENSHIFT_TMP_DIR/uwsgi.pid
Edit
.openshift/action_hooks/stop to the following:
kill `cat $OPENSHIFT_TMP_DIR/uwsgi.pid`
Deploy
Commit all of the changes to the repository:
git add .
git commit -am "initial commit"
Deploy to OpenShift:
git push
You should now be able to browse and see your application running:
curl http://py27-[namespace].rhcloud.com
Should return:
Hello from Flask
And to verify that your application is using Python 2.7:
curl http://py27-[namespace].rhcloud.com/info
Should return:
2.7.3
from https://www.openshift.com/blogs/enabling-python-27-on-a-paas-with-the-openshift-diy-app-type
