OpenShift Flask Template

It's the example for using flask on OpenShift.

Development

Structure

openshift-flask-template  # Project name
├── .s2i
│   └── environment       # Settings for s2i image. Already listed common settings for the image.
├── apis
│   ├── __init__.py       # Collect all apis
│   └── time.py           # An api example.  
├── configs
│   └── production.py     # Settings for gunicorn, you can create another for testing purpose.
├── core
│   ├── __init__.py
│   └── connection.py     # The feature related with server/RDB connection. 
├── nginx.conf            # [Optional] If you want to deploy with nginx, this file can help you.
├── requirements.txt      # List required packages.
├── template.yaml         # The template to help you to deploy the application to openshift without pain in first time.
└── wsgi.py               # Entry point for the project

Procedures

1. git clone this project.

2. Create a virtual environment through conda or other python virtual environment tool. More information can check following pages:

   • Flask-Restplus official website
   • Scaling your project
   • Request Parsing
   • Response marshalling

3. Rely on IDE's feature to install package automatically or use following command:

   pip install -r requirements.txt

4. Add new api to apis folder and modiftied __init__.py as well.

5. Run for debugging. You can use IDE to run wsgi.py main function or

   # Execution by python
   python wsgi.py
   
   # Execute with gunicorn
   gunicorn -c configs/production.py -b 0.0.0.0:8080 wsgi application

Support Images

There're 2 images can help you to deploy your application easily.

OpenShift Official Python image

OpenShift offers a Python image which support deploy pthon code or Django application. You can just select the python template from OpenShift console and given this git repo. And everything should work fine.

• Default port: 8080

A predefined Python-Nginx image

If you want to make the web application work behind Nginx as a single application on OpenShift, you can follow by the repo to build your own. The image spec:

• Gunicorn port: 8081
• Nginx port: 8080

If you already have an application which is using OpenShift Python image, change the base image to this new one can even work fine.

I also provide a Django example with SimpleUI for this customized image, you should refer to the repo.

Deployment on OpenShift

After you choose the following image that you want, you can use template file to help you deploy your application to openshift. There's two options to use template file. Just chooes the one you like and try it.

Deploy by Openshift console

1. On Browse Catalog page, choose Import YAML / JSON (It may hide in Custom Adddrop down list).
2. Choose the template file and then it'll show you what parameters that you should fill in. Note that, label app need to fill in by yourself.

Deploy by Openshift Cli

# Show all parameters
oc process --parameters -f template.yaml

# Swich to the project that you want to add new application
oc project <your_project_name>

# Add applicaiton to the project
oc new-app -f template.yaml -p NAME=<your_application_name>

# Show the progress for the build and the deployment
oc logs -f bc/<your_application_name>