Table of Contents
This quickstart will get you going with a Python/Django application that uses a Postgres database, deployed to Heroku. For other Python apps, see Getting Started with Python on Heroku. For general information on how to develop and architect apps for use on Heroku, see Architecting Applications for Heroku.
If you have questions about Python on Heroku, consider discussing it in the Python on Heroku forums. Both Heroku and community-based Python experts are available.
- The Heroku toolbelt, as described in Getting Started with Python.
- Installed Python and Virtualenv in a unix-style environment. See this guide for guidance.
- An installed version of Postgres to test locally.
- A Heroku user account. Signup is free and instant.
Start a Django app inside a Virtualenv
First, we’ll create an empty top-level directory for our project:
$ mkdir hellodjango && cd hellodjango
Make sure you're using the latest virtualenv release. If you're using a version that comes with Ubuntu, you may need to add the
Next, we’ll create a Python Virtualenv (v1.0+):
$ virtualenv venv New python executable in venv/bin/python Installing setuptools, pip...done.
To use the new virtualenv, we need to activate it. (You must source the virtualenv environment for each terminal session where you wish to run your app.)
$ source venv/bin/activate
Next, install our application’s dependencies with pip. In this case, we will be installing django-toolbelt, which includes all of the packages we need:
- Django (the web framework)
- Gunicorn (WSGI server)
- dj-database-url (a Django configuration helper)
- dj-static (a Django static file server)
From your virtualenv:
$ pip install django-toolbelt Installing collected packages: Django, psycopg2, gunicorn, dj-database-url, dj-static, static ... Successfully installed Django psycopg2 gunicorn dj-database-url dj-static static Cleaning up...
Now that we have a clean Python environment to work in, we’ll create our simple Django application.
Don't forget the
. at the end. This tells Django to put the extract the into the current directory, instead of putting it in a new subdirectory.
$ django-admin.py startproject hellodjango .
Declare process types with Procfile
Use a Procfile, a text file in the root directory of your application, to explicitly declare what command should be executed to start a web dyno. In this case, you need to execute Gunicorn with a few arguments.
Procfile for our new app. It should be called
Procfile and live at the root directory of our project:
web: gunicorn hellodjango.wsgi
You can now start the processes in your Procfile locally using Foreman (installed as part of the Toolbelt):
$ foreman start 2013-04-03 16:11:22  [INFO] Starting gunicorn 0.17.2 2013-04-03 16:11:22  [INFO] Listening at: http://127.0.0.1:8000 (8469)
Make sure things are working properly
curl or a web browser, then Ctrl-C to exit.
Specify dependencies with Pip
Heroku recognizes Python applications by the existence of a
requirements.txt file in the root of a repository. This simple format is used by most Python projects to specify the external Python modules the application requires.
Pip has a nice command (
pip freeze) that will generate this file for us:
$ pip freeze > requirements.txt
Django==1.6 dj-database-url==0.2.2 dj-static==0.0.5 gunicorn==18.0 psycopg2==2.5.1 static==0.4 wsgiref==0.1.2
Pip can also be used for advanced dependency management. See Python Dependencies via Pip to learn more.
Next, configure the application for the Heroku environment, including Heroku’s Postgres database. The dj-database-url module will parse the values of the
DATABASE_URL environment variable and convert them to something Django can understand.
Make sure ‘dj-database-url’ is in your requirements file, then add the following to the bottom of your
# Parse database configuration from $DATABASE_URL import dj_database_url DATABASES['default'] = dj_database_url.config() # Honor the 'X-Forwarded-Proto' header for request.is_secure() SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https') # Allow all host headers ALLOWED_HOSTS = ['*'] # Static asset configuration import os BASE_DIR = os.path.dirname(os.path.abspath(__file__)) STATIC_ROOT = 'staticfiles' STATIC_URL = '/static/' STATICFILES_DIRS = ( os.path.join(BASE_DIR, 'static'), )
With these settings available, you can add the following code to
wsgi.py to serve static files in production:
from django.core.wsgi import get_wsgi_application from dj_static import Cling application = Cling(get_wsgi_application())
Store your app in Git
Now that we’ve written and tested our application, we need to store the project in a Git repository.
Since our current directory contains a lof of extra files, we’ll want to configure our repository to ignore these files with a
venv *.pyc staticfiles
Next, we’ll create a new git repository and save our changes.
$ git init Initialized empty Git repository in /Users/kreitz/hellodjango/.git/ $ git add . $ git commit -m "my django app" [master (root-commit) 2943412] my django app 7 files changed, 230 insertions(+) create mode 100644 .gitignore create mode 100644 Procfile create mode 100644 hellodjango/__init__.py create mode 100644 hellodjango/settings.py create mode 100644 hellodjango/urls.py create mode 100644 hellodjango/wsgi.py create mode 100644 manage.py create mode 100644 requirements.txt
Deploy to Heroku
The next step is to push the application’s repository to Heroku. First, we have to get a place to push to from Heroku. We can do this with the
heroku create command:
$ heroku create Creating simple-spring-9999... done, stack is cedar http://simple-spring-9999.herokuapp.com/ | email@example.com:simple-spring-9999.git Git remote heroku added
This automatically added the Heroku remote for our app (
firstname.lastname@example.org:simple-spring-9999.git) to our repository. Now we can do a simple
git push to deploy our application:
$ git push heroku master Counting objects: 11, done. Delta compression using up to 4 threads. Compressing objects: 100% (9/9), done. Writing objects: 100% (11/11), 4.01 KiB, done. Total 11 (delta 0), reused 0 (delta 0) -----> Python app detected -----> No runtime.txt provided; assuming python-2.7.6. -----> Preparing Python runtime (python-2.7.6) -----> Installing Distribute (0.6.36) -----> Installing Pip (1.3.1) -----> Installing dependencies using Pip (1.3.1) Downloading/unpacking Django==1.5 (from -r requirements.txt (line 1)) ... Successfully installed Django psycopg2 gunicorn dj-database-url dj-static static Cleaning up... -----> Collecting static files 0 static files copied. -----> Discovering process types Procfile declares types -> web -----> Compiled slug size is 29.5MB -----> Launching... done, v6 http://simple-spring-9999.herokuapp.com deployed to Heroku To email@example.com:simple-spring-9999.git * [new branch] master -> master
Visit your application
You’ve deployed your code to Heroku, and specified the process types in a
Procfile. You can now instruct Heroku to execute a process type. Heroku does this by running the associated command in a dyno - a lightweight container which is the basic unit of composition on Heroku.
Let’s ensure we have one dyno running the
web process type:
$ heroku ps:scale web=1
You can check the state of the app’s dynos. The
heroku ps command lists the running dynos of your application:
$ heroku ps === web: `gunicorn hellodjango.wsgi` web.1: up for 10s
Here, one dyno is running.
We can now visit the app in our browser with
$ heroku open Opening simple-spring-9999.herokuapp.com... done
You should see the satisfying “It worked!” Django welcome page.
Dyno sleeping and scaling
Having only a single web dyno running will result in the dyno going to sleep after one hour of inactivity. This causes a delay of a few seconds for the first request upon waking. Subsequent requests will perform normally.
To avoid this, you can scale to more than one web dyno. For example:
$ heroku ps:scale web=2
For each application, Heroku provides 750 free dyno-hours. Running your app at 2 dynos would exceed this free, monthly allowance, so let’s scale back:
$ heroku ps:scale web=1
View the logs
Heroku treats logs as streams of time-ordered events aggregated from the output streams of all the dynos running the components of your application. Heroku’s Logplex provides a single channel for all of these events.
View information about your running app using one of the logging commands,
$ heroku logs 2012-04-06T19:38:25+00:00 heroku[web.1]: State changed from created to starting 2012-04-06T19:38:29+00:00 heroku[web.1]: Starting process with command `gunicorn hellodjango.wsgi` 2012-04-06T19:38:29+00:00 app[web.1]: Validating models... 2012-04-06T19:38:29+00:00 app[web.1]: 2012-04-06T19:38:29+00:00 app[web.1]: 0 errors found 2012-04-06T19:38:29+00:00 app[web.1]: Django version 1.5, using settings 'hellodjango.settings' 2012-04-06T19:38:29+00:00 app[web.1]: Development server is running at http://0.0.0.0:6566/ 2012-04-06T19:38:29+00:00 app[web.1]: Quit the server with CONTROL-C. 2012-04-06T19:38:30+00:00 heroku[web.1]: State changed from starting to up 2012-04-06T19:38:32+00:00 heroku[slugc]: Slug compilation finished
Syncing the database
heroku run command lets you run one-off admin dynos. You can use this to sync the Django models with the database schema:
$ heroku run python manage.py syncdb Running python manage.py syncdb attached to terminal... up, run.1 Creating tables ... Creating table auth_permission Creating table auth_group_permissions Creating table auth_group Creating table auth_user_groups Creating table auth_user_user_permissions Creating table auth_user Creating table django_content_type Creating table django_session Creating table django_site You just installed Django's auth system, which means you don't have any superusers defined. Would you like to create one now? (yes/no): yes Username (leave blank to use 'u53976'): kenneth Email address: firstname.lastname@example.org Password: Password (again): Superuser created successfully. Installing custom SQL ... Installing indexes ... Installed 0 object(s) from 0 fixture(s)
Using the Django shell
Similarly, you can use
heroku run to get a Django shell for executing arbitrary code against your deployed app:
$ heroku run python manage.py shell Running python manage.py shell attached to terminal... up, run.1 Python 2.7.6 (default, Jan 16 2014, 02:39:37) [GCC 4.4.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. (InteractiveConsole) >>> from django.contrib.auth.models import User >>> User.objects.all() [<User: kenneth>]
Now that you’ve deployed your first Django application to Heroku, it’s time to take the next step! If if you’d like to learn more about Heroku, these articles are a great place to start.
- Django and Static Assets
- Specifying a Python Runtime
- Python Dependencies via Pip
- Background Tasks in Python with RQ