Python

Last updated 2nd June 2022

Objective

Python is a general purpose scripting language often used in web development. You can deploy Python apps on Web PaaS using a server or a project such as uWSGI.

Supported versions

Grid
2.7
3.5
3.6
3.7
3.8
3.9
3.10

Usage example

Run your own server

You can define any server to handle requests. Once you have it configured, add the following configuration to get it running on Web PaaS:

1. Specify one of the supported versions:

type: 'python:3.10'

2. Install the requirements for your app.

location=".platform.app.yaml"
dependencies:
    python3:
        pipenv: "2022.5.2"

hooks:
    build: |
              pipenv install --system --deploy

3. Define the command to start your web server:

location=".platform.app.yaml"
web:
    # Start your app with the configuration you define
    # You can replace the file location with your location
    commands:
        start: python server.py

Use uWSGI

You can also use uWSGI to manage your server. Follow these steps to get your server started.

1. Specify one of the supported versions:

type: 'python:3.10'

2. Define the conditions for your web server:

location=".platform.app.yaml"
web:
    upstream:
        # Send requests to the app server through a unix socket
        # Its location is defined in the SOCKET environment variable
        socket_family: "unix"

    # Start your app with the configuration you define
    # You can replace the file location with your location
    commands:
        start: "uwsgi --ini conf/uwsgi.ini"

    locations:
        # The folder from which to serve static assets
        "/":
            root: "public"
            passthru: true
            expires: 1h

3. Create configuration for uWSGI such as the following:

location="config/uwsgi.ini"
[uwsgi]
 # UNIX socket to use to talk with the web server
 # Uses the variable defined in the configuration in step 2
 socket = $(SOCKET)
 protocol = http

 # the entry point to your app
 wsgi-file = app.py

Replace app.py with whatever your file is.

4. Install the requirements for your app.

   dependencies:
    python3:
        pipenv: "2022.5.2"

hooks:
    build: |
              pipenv install --system --deploy

5. Define the entry point in your app:

# You can name the function differently and pass the new name as a flag
# start: "uwsgi --ini conf/uwsgi.ini --callable <NAME>"
def application(env, start_response):

    start_response('200 OK', [('Content-Type', 'text/html')])
    return [b"Hello world from Web PaaS"]

Package management

Your app container comes with pip pre-installed. To add global dependencies (packages available as commands), add them to the dependencies in your app configuration:

location=".platform.app.yaml"
dependencies:
    python3:
        <PACKAGE_NAME>: <PACKAGE_VERSION>
dependencies:
    python3:
        pipenv: "2022.5.2"

hooks:
    build: |
              pipenv install --system --deploy

Connect to services

The following examples show how to access various services with Python. For more information on configuring a given service, see the page for that service.

import elasticsearch
from platformshconfig import Config

def usage_example():

    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # Get the credentials to connect to the Elasticsearch service.
    credentials = config.credentials('elasticsearch')

    try:
        # The Elasticsearch library lets you connect to multiple hosts.
        # On Web PaaS Standard there is only a single host so just register that.
        hosts = {
            "scheme": credentials['scheme'],
            "host": credentials['host'],
            "port": credentials['port']
        }

        # Create an Elasticsearch client object.
        client = elasticsearch.Elasticsearch([hosts])

        # Index a few documents
        es_index = 'my_index'
        es_type = 'People'

        params = {
            "index": es_index,
            "type": es_type,
            "body": {"name": ''}
        }

        names = ['Ada Lovelace', 'Alonzo Church', 'Barbara Liskov']

        ids = {}

        for name in names:
            params['body']['name'] = name
            ids[name] = client.index(index=params["index"], doc_type=params["type"], body=params['body'])

        # Force just-added items to be indexed.
        client.indices.refresh(index=es_index)

        # Search for documents.
        result = client.search(index=es_index, body={
            'query': {
                'match': {
                    'name': 'Barbara Liskov'
                }
            }
        })

        table = '''<table>
<thead>
<tr><th>ID</th><th>Name</th></tr>
</thead>
<tbody>'''

        if result['hits']['hits']:
            for record in result['hits']['hits']:
                table += '''<tr><td>{0}</td><td>{1}</td><tr>\n'''.format(record['_id'], record['_source']['name'])
            table += '''</tbody>\n</table>\n'''

        # Delete documents.
        params = {
            "index": es_index,
            "type": es_type,
        }

        for name in names:
            client.delete(index=params['index'], doc_type=params['type'], id=ids[name]['_id'])

        return table

    except Exception as e:
        return e
from json import dumps
from json import loads
from kafka import KafkaConsumer, KafkaProducer
from platformshconfig import Config


def usage_example():
    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()
    # Get the credentials to connect to the Kafka service.
    credentials = config.credentials('kafka')

    try:
        kafka_server = '{}:{}'.format(credentials['host'], credentials['port'])

        # Producer
        producer = KafkaProducer(
            bootstrap_servers=[kafka_server],
            value_serializer=lambda x: dumps(x).encode('utf-8')
        )
        for e in range(10):
            data = {'number' : e}
            producer.send('numtest', value=data)

        # Consumer
        consumer = KafkaConsumer(
            bootstrap_servers=[kafka_server],
            auto_offset_reset='earliest'
        )

        consumer.subscribe(['numtest'])

        output = ''
        # For demonstration purposes so it doesn't block.
        for e in range(10):
            message = next(consumer)
            output += str(loads(message.value.decode('UTF-8'))["number"]) + ', '

        # What a real implementation would do instead.
        # for message in consumer:
        #     output += loads(message.value.decode('UTF-8'))["number"]

        return output

    except Exception as e:
        return e
import pymemcache
from platformshconfig import Config


def usage_example():

    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # Get the credentials to connect to the Memcached service.
    credentials = config.credentials('memcached')

    try:
        # Try connecting to Memached server.
        memcached = pymemcache.Client((credentials['host'], credentials['port']))
        memcached.set('Memcached::OPT_BINARY_PROTOCOL', True)

        key = "Deploy_day"
        value = "Friday"

        # Set a value.
        memcached.set(key, value)

        # Read it back.
        test = memcached.get(key)

        return 'Found value <strong>{0}</strong> for key <strong>{1}</strong>.'.format(test.decode("utf-8"), key)

    except Exception as e:
        return e
from pymongo import MongoClient
from platformshconfig import Config


def usage_example():

    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # The 'database' relationship is generally the name of primary SQL database of an application.
    # It could be anything, though, as in the case here here where it's called "mongodb".
    credentials = config.credentials('mongodb')

    try:
        formatted = config.formatted_credentials('mongodb', 'pymongo')

        server = '{0}://{1}:{2}@{3}'.format(
            credentials['scheme'],
            credentials['username'],
            credentials['password'],
            formatted
        )

        client = MongoClient(server)

        collection = client.main.starwars

        post = {
            "name": "Rey",
            "occupation": "Jedi"
        }

        post_id = collection.insert_one(post).inserted_id

        document = collection.find_one(
            {"_id": post_id}
        )

        # Clean up after ourselves.
        collection.drop()

        return 'Found {0} ({1})<br />'.format(document['name'], document['occupation'])

    except Exception as e:
        return e
import pymysql
from platformshconfig import Config


def usage_example():

    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # The 'database' relationship is generally the name of primary SQL database of an application.
    # That's not required, but much of our default automation code assumes it.'
    credentials = config.credentials('database')

    try:
        # Connect to the database using PDO. If using some other abstraction layer you would inject the values
        # from `database` into whatever your abstraction layer asks for.

        conn = pymysql.connect(host=credentials['host'],
                               port=credentials['port'],
                               database=credentials['path'],
                               user=credentials['username'],
                               password=credentials['password'])

        sql = '''
                CREATE TABLE People (
                id SERIAL PRIMARY KEY,
                name VARCHAR(30) NOT NULL,
                city VARCHAR(30) NOT NULL
                )
                '''

        cur = conn.cursor()
        cur.execute(sql)

        sql = '''
                INSERT INTO People (name, city) VALUES
                ('Neil Armstrong', 'Moon'),
                ('Buzz Aldrin', 'Glen Ridge'),
                ('Sally Ride', 'La Jolla');
                '''

        cur.execute(sql)

        # Show table.
        sql = '''SELECT * FROM People'''
        cur.execute(sql)
        result = cur.fetchall()

        table = '''<table>
<thead>
<tr><th>Name</th><th>City</th></tr>
</thead>
<tbody>'''

        if result:
            for record in result:
                table += '''<tr><td>{0}</td><td>{1}</td><tr>\n'''.format(record[1], record[2])
            table += '''</tbody>\n</table>\n'''

        # Drop table
        sql = '''DROP TABLE People'''
        cur.execute(sql)

        # Close communication with the database
        cur.close()
        conn.close()

        return table

    except Exception as e:
        return e
import psycopg2
from platformshconfig import Config


def usage_example():
    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # The 'database' relationship is generally the name of primary SQL database of an application.
    # That's not required, but much of our default automation code assumes it.' \
    database = config.credentials('postgresql')

    try:
        # Connect to the database.
        conn_params = {
            'host': database['host'],
            'port': database['port'],
            'dbname': database['path'],
            'user': database['username'],
            'password': database['password']
        }

        conn = psycopg2.connect(**conn_params)

        # Open a cursor to perform database operations.
        cur = conn.cursor()

        cur.execute("DROP TABLE IF EXISTS People")

        # Creating a table.
        sql = '''
                CREATE TABLE IF NOT EXISTS People (
                id SERIAL PRIMARY KEY,
                name VARCHAR(30) NOT NULL,
                city VARCHAR(30) NOT NULL
                )
                '''

        cur.execute(sql)

        # Insert data.
        sql = '''
                INSERT INTO People (name, city) VALUES
                ('Neil Armstrong', 'Moon'),
                ('Buzz Aldrin', 'Glen Ridge'),
                ('Sally Ride', 'La Jolla');
                '''

        cur.execute(sql)

        # Show table.
        sql = '''SELECT * FROM People'''
        cur.execute(sql)
        result = cur.fetchall()

        table = '''<table>
<thead>
<tr><th>Name</th><th>City</th></tr>
</thead>
<tbody>'''

        if result:
            for record in result:
                table += '''<tr><td>{0}</td><td>{1}</td><tr>\n'''.format(record[1], record[2])
            table += '''</tbody>\n</table>\n'''

        # Drop table
        sql = "DROP TABLE People"
        cur.execute(sql)

        # Close communication with the database
        cur.close()
        conn.close()

        return table

    except Exception as e:
        return e
import pika
from platformshconfig import Config


def usage_example():
    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # Get the credentials to connect to the RabbitMQ service.
    credentials = config.credentials('rabbitmq')

    try:
        # Connect to the RabbitMQ server
        creds = pika.PlainCredentials(credentials['username'], credentials['password'])
        parameters = pika.ConnectionParameters(credentials['host'], credentials['port'], credentials=creds)

        connection = pika.BlockingConnection(parameters)
        channel = connection.channel()

        # Check to make sure that the recipient queue exists
        channel.queue_declare(queue='deploy_days')

        # Try sending a message over the channel
        channel.basic_publish(exchange='',
                              routing_key='deploy_days',
                              body='Friday!')

        # Receive the message
        def callback(ch, method, properties, body):
            print(" [x] Received {}".format(body))

        # Tell RabbitMQ that this particular function should receive messages from our 'hello' queue
        channel.basic_consume('deploy_days',
                              callback,
                              auto_ack=False)

        # This blocks on waiting for an item from the queue, so comment it out in this demo script.
        # print(' [*] Waiting for messages. To exit press CTRL+C')
        # channel.start_consuming()

        connection.close()

        return " [x] Sent 'Friday!'<br/>"

    except Exception as e:
        return e
from redis import Redis
from platformshconfig import Config


def usage_example():

    # Create a new config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    # Get the credentials to connect to the Redis service.
    credentials = config.credentials('redis')

    try:
        redis = Redis(credentials['host'], credentials['port'])

        key = "Deploy day"
        value = "Friday"

        # Set a value
        redis.set(key, value)

        # Read it back
        test = redis.get(key)

        return 'Found value <strong>{0}</strong> for key <strong>{1}</strong>.'.format(test.decode("utf-8"), key)

    except Exception as e:
        return e
import pysolr
from xml.etree import ElementTree as et
import json
from platformshconfig import Config


def usage_example():

    # Create a new Config object to ease reading the Web PaaS environment variables.
    # You can alternatively use os.environ yourself.
    config = Config()

    try:
        # Get the pysolr-formatted connection string.
        formatted_url = config.formatted_credentials('solr', 'pysolr')

        # Create a new Solr Client using config variables
        client = pysolr.Solr(formatted_url)

        # Add a document
        message = ''
        doc_1 = {
            "id": 123,
            "name": "Valentina Tereshkova"
        }

        result0 = client.add([doc_1], commit=True)
        client.commit()
        message += 'Adding one document. Status (0 is success): {} <br />'.format(json.loads(result0)['responseHeader']['status'])

        # Select one document
        query = client.search('*:*')
        message += '\nSelecting documents (1 expected): {} <br />'.format(str(query.hits))

        # Delete one document
        result1 = client.delete(doc_1['id'])
        client.commit()
        message += '\nDeleting one document. Status (0 is success): {}'.format(et.fromstring(result1)[0][0].text)

        return message

    except Exception as e:
        return e

Configuration reader

While you can read the environment directly from your app, you might want to use the platformshconfig library. It decodes service credentials, the correct port, and other information for you.

Project templates

Django 2

image

This template deploys the Django 2 application framework on Web PaaS, using the gunicorn application runner. It also includes a PostgreSQL database connection pre-configured.

New projects should be built using Django 3, but this project is a reference for existing migrating sites. Version 2 is in legacy support.

Features

  • Python 3.8
  • PostgreSQL 12
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Pelican

image

This template provides a basic Pelican skeleton. Only content files need to be committed, as Pelican itself is downloaded at build time via the Pipfile. All files are generated at build time, so at runtime only static files need to be served.

Pelican is a static site generator written in Python and using Jinja for templating.

Features

  • Python 3.8
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Wagtail

image

This template builds the Wagtail CMS on Web PaaS, using the gunicorn application runner. It includes a PostgreSQL database that is configured automatically, and a basic demonstration app that shows how to use it. It is intended for you to use as a starting point and modify for your own needs. You will need to run the command line installation process by logging into the project over SSH after the first deploy.

Wagtail is a web CMS built using the Django framework for Python.

Features

  • Python 3.8
  • PostgreSQL 12
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Flask

image

This template demonstrates building the Flask framework for Web PaaS. It includes a minimalist application skeleton that demonstrates how to connect to a MariaDB server for data storage and Redis for caching. The application starts as a bare Python process with no separate runner. It is intended for you to use as a starting point and modify for your own needs.

Flask is a lightweight web microframework for Python.

Features

  • Python 3.8
  • MariaDB 10.4
  • Redis 5.0
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Django 3

image

This template deploys the Django 3 application framework on Web PaaS, using the gunicorn application runner. It also includes a PostgreSQL database connection pre-configured.

Django is a Python-based web application framework with a built-in ORM.

Features

  • Python 3.8
  • PostgreSQL 12
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Pyramid

image

This template builds Pyramid on Web PaaS. It includes a minimalist application skeleton that demonstrates how to connect to a MariaDB server for data storage and Redis for caching. It is intended for you to use as a starting point and modify for your own needs.

Pyramid is a web framework written in Python.

Features

  • Python 3.8
  • MariaDB 10.4
  • Redis 5.0
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Basic Python 3

image

This template provides the most basic configuration for running a custom Python 3.7 project. It includes the `platformshconfig` package and demonstrates using it to connect to MariaDB and Redis. It can be used to build a very rudimentary application but is intended primarily as a documentation reference. The application starts as a bare Python process with no separate runner.

Python is a general purpose scripting language often used in web development.

Features

  • Python 3.8
  • MariaDB 10.4
  • Redis 5.0
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.

Python 3 running UWSGI

image

This template provides the most basic configuration for running a custom Python 3.7 project. It includes the `platformshconfig` package and demonstrates using it to connect to MariaDB and Redis. It can be used to build a very rudimentary application but is intended primarily as a documentation reference. The application runs through the UWSGI runner.

Python is a general purpose scripting language often used in web development.

Features

  • Python 3.8
  • MariaDB 10.4
  • Redis 5.0
  • Automatic TLS certificates
  • Pipfile-based build

View the repository on GitHub.


Did you find this guide useful?

Please feel free to give any suggestions in order to improve this documentation.

Whether your feedback is about images, content, or structure, please share it, so that we can improve it together.

Your support requests will not be processed via this form. To do this, please use the "Create a ticket" form.

Thank you. Your feedback has been received.


These guides might also interest you...

OVHcloud Community

Access your community space. Ask questions, search for information, post content, and interact with other OVHcloud Community members.

Discuss with the OVHcloud community

In accordance with the 2006/112/CE Directive, modified on 01/01/2015, prices incl. VAT may vary according to the customer's country of residence
(by default, the prices displayed are inclusive of the UK VAT in force).