This is a simple demo of using Cloud Foundry, Flask, and Python 3.
- You must have at minimum a Predix Free Tier account.
- You must have the Cloud Foundry CLI and can run
cf login
git clone https://github.com/j12y/predix-py3-flask.git
cd predix-py3-flask
You'll want to change the application name to something unique just for you.
cf push
With a successful push you should be able to go to a URL such as:
https://py3-cf-demo.run.aws-usw02-pr.ice.predix.io/
Which will just print some text in your browser
3.5.3 (default, Jan 20 2017, 17:01:29) [GCC 4.8.4]
The Procfile informs Cloud Foundry what service to run when invoked. In this
sample, it is simply python app.py which will run our code. This is suitable
for demo purposes, but you may want to substitute a production web server such
as gunicorn for final applications.
The app.py is a simple Flask demo. With Cloud Foundry the PORT you should
use is exposed as an environment variable. You can also run your flask app
without pushing to Predix by running python app.py where it will look for a
PORT environment variable or default to something such as
http://localhost:8080/.
If you are unfamiliar with Flask there are many great resources if you search.
The manifest.yml is used by Cloud Foundry to identify some details of how
your application should be cf pushed. This example is pretty simple but
there are many other settings you can specify. The name must be unique
across a Predix Availability Zone, so you may see an error:
Binding py3-cf-demo.run.aws-usw02-pr.ice.predix.io to py3-cf-demo...
FAILED
The route py3-cf-demo.run.aws-usw02-pr.ice.predix.io is already in use.
This simply means you need to give your app a unique name because the name is part of the URL used in the resulting app.
The python buildpack is optional to specify, in this example we are pulling the latest version from github instead of using what the default would be in Predix.
The python buildpack for Cloud Foundry will make sure to pip install anything
found in the requirements.txt and is needed for your application to run. If
you have your own libraries not available on PyPI you may need to "vendor"
those dependencies.
The python buildpack for Cloud Foundry will look for this file and if found will use a python version that corresponds. Not every version of Python is supported, so check the buildpack documentation for additional details.
If this file is absent you will default to a py2.x version.