python

Deploying Python App using S2I to Openshift Container Platform

By / 27 January 2025 / Programming, Python / , ,

For this sample, we are trying to deploy a Flask application to Openshift without any CI/CD tools involved. Means we are deploying directly by using S2I functionality thru OCP Dashboard.

Lets start with a simple hello world Python application, it is basically one simple py file

from flask import Flask

app = Flask(__name__)

@app.route("/")
def index():
    return "<h1>Hello, World!</h1>"

app.run(host="0.0.0.0", port=8080)

and one requirements.txt file,

flask

And after that, we can push our complete Python code to a Git repository. For example, im using below Git repo,

https://github.com/edwin/hello-world-flask

We can deploy to Openshift from the Developer dashboard,

Put the Git repo URL there

It will trigger a build process

Would took a while

But it will deployed successfully after a while

We can access the deployed apps directly after we expose a Route to our app.

Containerizing Python Flask App, and Deploy it into Openshift

By / 6 April 2022 / Programming, Python / , ,

Lets say for example i have a very simple python code, the goal is only to construct an html page and display it to user.

from flask import Flask, render_template

app = Flask(__name__)

@app.route("/")
def index():
    return render_template('index.html', message="Hello World..!!")

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=5000, debug=True)

An HTML template file,

<!DOCTYPE html>
<html>
	<head>
		<title>Hello World Python</title>
	</head>
	<body>

		<h1>
			{{ message }}
		</h1>

	</body>
</html>

And requirements.txt

flask

Above Python code can be build into a container image by using a simple Dockerfile,

FROM registry.access.redhat.com/ubi8/python-39:latest

WORKDIR /deployment

COPY app.py /deployment
COPY templates/* /deployment/templates/
COPY requirements.txt /deployment

RUN pip3 install -r requirements.txt

EXPOSE 5000

CMD [ "python3", "-m" , "flask", "run", "--host=0.0.0.0"]

And make sure that the folder structure will be like below,

.
+--- app.py
+--- Dockerfile
+--- README.md
+--- requirements.txt
+--- templates
|   +--- index.html

Now the next thing to do is deploying this app into Openshift, we can start by running below command in the code’s folder.

$ oc new-build --strategy docker --binary --name=containerized-hello-world-python 

$ oc start-build containerized-hello-world-python  --from-dir=. --follow --wait

$ oc new-app containerized-hello-world-python  --name=containerized-hello-world-python 

$ oc create route edge --service=containerized-hello-world-python

Code can be accessed in below git repository

https://github.com/edwin/containerized-hello-world-python

Have fun with Python.

Deploying a Python app to Openshift 4 using s2i

By / 11 March 2022 / Openshift, Programming, Python / , , ,

S2I or Source to Image, is a way to deploy application from its sourcecode directly to Openshift. In this article, we try to build a Python apps with Flask framework and deploy it to Openshift.

So lets start with requirements.txt for storing required libraries 

flask

And a simple hello world app

from flask import Flask

app = Flask(__name__)

@app.route("/")
def index():
    return "<h1>Hello, World!</h1>"

app.run(host="0.0.0.0", port=8080)

Next is where the magic happens, it would build, containerized and push the whole apps to external registry by using below commands,

$ oc new-build . --name=hello-world-python --to-docker --to=docker.io/dockerusername/hello-world-python

$ oc start-build hello-world-python --from-dir=. --follow --wait

Once we push it to external registry, we can pull and run the apps in Openshift

$ oc new-app . --docker-image=dockerusername/hello-world-python --name=hello-world-python-app

And expose a secure URL for it,

$ oc create route edge --service=hello-world-python-app

Code for this can be accessed here,

https://github.com/edwin/hello-world-flask

[Python] Fixing Fatal Error when Installing Mysqlclient with Pip

By / 29 October 2018 / Programming, Python / , ,

On my current project, im using Python, Django and Pip. But there is some issue when installing libraries needed for running the app,

pip install -r requirements.txt

Below is the error generated when running it,

_mysql.c:29:10: fatal error: 'my_config.h' file not found
   #include "my_config.h"
            ^~~~~~~~~~~~~
   1 error generated.
   error: command 'clang' failed with exit status 1
----------------------------------------
 Rolling back uninstall of mysqlclient

Looks like error happen when trying to install below library,

mysqlclient==1.3.7

Below is Python and Pip version that im using,

 
$ python --version
Python 3.4.3

$ pip -V
pip 18.1 from /Users/m/.pyenv/versions/3.4.3/envs/logistic_backend/lib/python3.4/site-packages/pip (python 3.4)

The main culprit is corresponding library is not supported by Python 3.4.3, changing it into below lib fix the error

pymysql==0.9.2