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DotCloud

DotCloud offers support for all WSGI frameworks. Below is a quickstart guide for Pyramid apps. You can also read the DotCloud Python documentation for a complete overview.

Step 0: Install DotCloud

Install DotCloud’s CLI by running:

$ pip install dotcloud

Step 1: Add files needed for DotCloud

DotCloud expects Python applications to have a few files in the root of the project. First, you need a pip requirements.txt file to instruct DotCloud which Python library dependencies to install for your app. Secondly you need a dotcloud.yaml file which informs DotCloud that your application has (at a minimum) a Python service. You may also want additional services such as a MongoDB database or PostgreSQL database and so on - these things are all specified in YAML.

Finally, you will need a file named wsgi.py which is what the DotCloud uWSGI server is configured to look for. This wsgi.py script needs to create a WSGI callable for your Pyramid app which must be present in a global named “application”.

You’ll need to add a requirements.txt, dotcloud.yml, and wsgi.py file to the root directory of your app. Here are some samples for a basic Pyramid app:

requirements.txt:

cherrypy
Pyramid==1.3
# Add any other dependencies that should be installed as well

dotcloud.yml:

www:
    type: python
db:
    type: postgresql

Learn more about the DotCloud buildfile.

wsgi.py:

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# Your WSGI callable should be named “application”, be located in a
# "wsgi.py" file, itself located at the top directory of the service.
#
# For example, to load the app from your "production.ini" file in the same
# directory:
import os.path
from pyramid.scripts.pserve import cherrypy_server_runner
from pyramid.paster import get_app

application = get_app(os.path.join(os.path.dirname(__file__), 'production.ini'))

if __name__ == "__main__":
    cherrypy_server_runner(application, host="0.0.0.0")

Step 2: Configure your database

If you specified a database service in your dotcloud.yml, the connection info will be made available to your service in a JSON file at /home/dotcloud/environment.json. For example, the following code would read the environment.json file and add the PostgreSQL URL to the settings of your pyramid app:

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import json

# if dotcloud, read PostgreSQL URL from environment.json
db_uri = settings['postgresql.url']
DOTCLOUD_ENV_FILE = "/home/dotcloud/environment.json"
if os.path.exists(DOTCLOUD_ENV_FILE):
    with open(DOTCLOUD_ENV_FILE) as f:
        env = json.load(f)
        db_uri = env["DOTCLOUD_DATA_POSTGRESQL_URL"]

Learn more about the DotCloud environment.json.

Step 3: Deploy your app

Now you can deploy your app. Remember to commit your changes if you’re using Mercurial or Git, then run these commands in the top directory of your app:

$ dotcloud create your_app_name
$ dotcloud push your_app_name

At the end of the push, you’ll see the URL(s) for your new app. Have fun!

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