Setting up Django and your web server with uWSGI and nginx ========================================================== .. highlight:: bash This tutorial is aimed at the Django user who wants to set up a production web server. It takes you through the steps required to set up Django so that it works nicely with uWSGI and nginx. It covers all three components, providing a complete stack of web application and server software. Django_ is a high-level Python Web framework that encourages rapid development and clean, pragmatic design. .. _Django: http://djangoproject.com/ nginx_ (pronounced *engine-x*) is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. .. _nginx: http://nginx.org/ Some notes about this tutorial ------------------------------ .. admonition:: Note This is a **tutorial**. It is not intended to provide a reference guide, never mind an exhaustive reference, to the subject of deployment. nginx and uWSGI are good choices for Django deployment, but they are not the only ones, or the 'official' ones. There are excellent alternatives to both, and you are encouraged to investigate them. The way we deploy Django here is a good way, but it is **not** the *only* way; for some purposes it is probably not even the best way. It is however a reliable and easy way, and the material covered here will introduce you to concepts and procedures you will need to be familiar with whatever software you use for deploying Django. By providing you with a working setup, and rehearsing the steps you must take to get there, it will offer you a basis for exploring other ways to achieve this. .. admonition:: Note This tutorial makes some assumptions about the system you are using. It is assumed that you are using a Unix-like system, and that it features an aptitude-like package manager. However if you need to ask questions like "What's the equivalent of aptitude on Mac OS X?", you'll be able to find that kind of help fairly easily. While this tutorial assumes Django 1.4 or later, which will automatically create a wsgi module in your new project, the instructions will work with earlier versions. You will though need to obtain that Django wsgi module yourself, and you may find that the Django project directory structure is slightly different. Concept ------- A web server faces the outside world. It can serve files (HTML, images, CSS, etc) directly from the file system. However, it can't talk *directly* to Django applications; it needs something that will run the application, feed it requests from web clients (such as browsers) and return responses. A Web Server Gateway Interface - WSGI - does this job. WSGI_ is a Python standard. .. _WSGI: http://wsgi.org/ uWSGI is a WSGI implementation. In this tutorial we will set up uWSGI so that it creates a Unix socket, and serves responses to the web server via the uwsgi protocol. At the end, our complete stack of components will look like this:: the web client <-> the web server <-> the socket <-> uwsgi <-> Django Before you start setting up uWSGI --------------------------------- virtualenv ^^^^^^^^^^ Make sure you are in a virtualenv for the software we need to install (we will describe how to install a system-wide uwsgi later): .. code-block:: bash virtualenv uwsgi-tutorial cd uwsgi-tutorial source bin/activate Django ^^^^^^ Install Django into your virtualenv, create a new project, and ``cd`` into the project: .. code-block:: bash pip install Django django-admin.py startproject mysite cd mysite About the domain and port ^^^^^^^^^^^^^^^^^^^^^^^^^ In this tutorial we will call your domain ``example.com``. Substitute your own FQDN or IP address. Throughout, we'll be using port 8000 for the web server to publish on, just like the Django runserver does by default. You can use whatever port you want of course, but I have chosen this one so it doesn't conflict with anything a web server might be doing already. Basic uWSGI installation and configuration ------------------------------------------ Install uWSGI into your virtualenv ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. code-block:: bash pip install uwsgi Of course there are other ways to install uWSGI, but this one is as good as any. Remember that you will need to have Python development packages installed. In the case of Debian, or Debian-derived systems such as Ubuntu, what you need to have installed is ``pythonX.Y-dev``, where X.Y is your version of Python. Basic test ^^^^^^^^^^ Create a file called ``test.py``:: # test.py def application(env, start_response): start_response('200 OK', [('Content-Type','text/html')]) return [b"Hello World"] # python3 #return ["Hello World"] # python2 .. note:: Take into account that Python 3 requires ``bytes()``. Run uWSGI: .. code-block:: bash uwsgi --http :8000 --wsgi-file test.py The options mean: * ``http :8000``: use protocol http, port 8000 * ``wsgi-file test.py``: load the specified file, test.py This should serve a 'hello world' message directly to the browser on port 8000. Visit:: http://example.com:8000 to check. If so, it means the following stack of components works:: the web client <-> uWSGI <-> Python Test your Django project ^^^^^^^^^^^^^^^^^^^^^^^^ Now we want uWSGI to do the same thing, but to run a Django site instead of the ``test.py`` module. If you haven't already done so, make sure that your ``mysite`` project actually works:: python manage.py runserver 0.0.0.0:8000 And if that works, run it using uWSGI:: uwsgi --http :8000 --module mysite.wsgi * ``module mysite.wsgi``: load the specified wsgi module Point your browser at the server; if the site appears, it means uWSGI is able to serve your Django application from your virtualenv, and this stack operates correctly:: the web client <-> uWSGI <-> Django Now normally we won't have the browser speaking directly to uWSGI. That's a job for the webserver, which will act as a go-between. Basic nginx ----------- Install nginx ^^^^^^^^^^^^^ .. code-block:: bash sudo apt-get install nginx sudo /etc/init.d/nginx start # start nginx And now check that nginx is serving by visiting it in a web browser on port 80 - you should get a message from nginx: "Welcome to nginx!". That means these components of the full stack are working together:: the web client <-> the web server If something else *is* already serving on port 80 and you want to use nginx there, you'll have to reconfigure nginx to serve on a different port. For this tutorial though, we're going to be using port 8000. Configure nginx for your site ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ You will need the ``uwsgi_params`` file, which is available in the ``nginx`` directory of the uWSGI distribution, or from https://github.com/nginx/nginx/blob/master/conf/uwsgi_params Copy it into your project directory. In a moment we will tell nginx to refer to it. Now create a file called mysite_nginx.conf in the /etc/nginx/sites-available/ directory, and put this in it:: # mysite_nginx.conf # the upstream component nginx needs to connect to upstream django { # server unix:///path/to/your/mysite/mysite.sock; # for a file socket server 127.0.0.1:8001; # for a web port socket (we'll use this first) } # configuration of the server server { # the port your site will be served on listen 8000; # the domain name it will serve for server_name example.com; # substitute your machine's IP address or FQDN charset utf-8; # max upload size client_max_body_size 75M; # adjust to taste # Django media location /media { alias /path/to/your/mysite/media; # your Django project's media files - amend as required } location /static { alias /path/to/your/mysite/static; # your Django project's static files - amend as required } # Finally, send all non-media requests to the Django server. location / { uwsgi_pass django; include /path/to/your/mysite/uwsgi_params; # the uwsgi_params file you installed } } This conf file tells nginx to serve up media and static files from the filesystem, as well as handle requests that require Django's intervention. For a large deployment it is considered good practice to let one server handle static/media files, and another handle Django applications, but for now, this will do just fine. Symlink to this file from /etc/nginx/sites-enabled so nginx can see it: .. code-block:: bash sudo ln -s /etc/nginx/sites-available/mysite_nginx.conf /etc/nginx/sites-enabled/ Deploying static files ^^^^^^^^^^^^^^^^ Before running nginx, you have to collect all Django static files in the static folder. First of all you have to edit mysite/settings.py adding: .. code-block:: Python STATIC_ROOT = os.path.join(BASE_DIR, "static/") and then run .. code-block:: bash python manage.py collectstatic Basic nginx test ^^^^^^^^^^^^^^^^ Restart nginx: .. code-block:: bash sudo /etc/init.d/nginx restart To check that media files are being served correctly, add an image called ``media.png`` to the ``/path/to/your/project/project/media directory``, then visit http://example.com:8000/media/media.png - if this works, you'll know at least that nginx is serving files correctly. It is worth not just restarting nginx, but actually stopping and then starting it again, which will inform you if there is a problem, and where it is. nginx and uWSGI and test.py --------------------------- Let's get nginx to speak to the "hello world" ``test.py`` application. .. code-block:: bash uwsgi --socket :8001 --wsgi-file test.py This is nearly the same as before, except this time one of the options is different: * ``socket :8001``: use protocol uwsgi, port 8001 nginx meanwhile has been configured to communicate with uWSGI on that port, and with the outside world on port 8000. Visit: http://example.com:8000/ to check. And this is our stack:: the web client <-> the web server <-> the socket <-> uWSGI <-> Python Meanwhile, you can try to have a look at the uwsgi output at http://example.com:8001 - but quite probably, it won't work because your browser speaks http, not uWSGI, though you should see output from uWSGI in your terminal. Using Unix sockets instead of ports ----------------------------------- So far we have used a TCP port socket, because it's simpler, but in fact it's better to use Unix sockets than ports - there's less overhead. Edit ``mysite_nginx.conf``, changing it to match:: server unix:///path/to/your/mysite/mysite.sock; # for a file socket # server 127.0.0.1:8001; # for a web port socket (we'll use this first) and restart nginx. Run uWSGI again: .. code-block:: bash uwsgi --socket mysite.sock --wsgi-file test.py This time the ``socket`` option tells uWSGI which file to use. Try http://example.com:8000/ in the browser. If that doesn't work ^^^^^^^^^^^^^^^^^^^^ Check your nginx error log(/var/log/nginx/error.log). If you see something like:: connect() to unix:///path/to/your/mysite/mysite.sock failed (13: Permission denied) then probably you need to manage the permissions on the socket so that nginx is allowed to use it. Try:: uwsgi --socket mysite.sock --wsgi-file test.py --chmod-socket=666 # (very permissive) or:: uwsgi --socket mysite.sock --wsgi-file test.py --chmod-socket=664 # (more sensible) You may also have to add your user to nginx's group (which is probably www-data), or vice-versa, so that nginx can read and write to your socket properly. It's worth keeping the output of the nginx log running in a terminal window so you can easily refer to it while troubleshooting. Running the Django application with uwsgi and nginx --------------------------------------------------- Let's run our Django application: .. code-block:: bash uwsgi --socket mysite.sock --module mysite.wsgi --chmod-socket=664 Now uWSGI and nginx should be serving up not just a "Hello World" module, but your Django project. Configuring uWSGI to run with a .ini file ----------------------------------------- We can put the same options that we used with uWSGI into a file, and then ask uWSGI to run with that file. It makes it easier to manage configurations. Create a file called ```mysite_uwsgi.ini```:: # mysite_uwsgi.ini file [uwsgi] # Django-related settings # the base directory (full path) chdir = /path/to/your/project # Django's wsgi file module = project.wsgi # the virtualenv (full path) home = /path/to/virtualenv # process-related settings # master master = true # maximum number of worker processes processes = 10 # the socket (use the full path to be safe socket = /path/to/your/project/mysite.sock # ... with appropriate permissions - may be needed # chmod-socket = 664 # clear environment on exit vacuum = true And run uwsgi using this file: .. code-block:: bash uwsgi --ini mysite_uwsgi.ini # the --ini option is used to specify a file Once again, test that the Django site works as expected. Install uWSGI system-wide ------------------------- So far, uWSGI is only installed in our virtualenv; we'll need it installed system-wide for deployment purposes. Deactivate your virtualenv:: deactivate and install uWSGI system-wide:: sudo pip install uwsgi # Or install LTS (long term support). pip install https://projects.unbit.it/downloads/uwsgi-lts.tar.gz The uWSGI wiki describes several `installation procedures`_. Before installing uWSGI system-wide, it's worth considering which version to choose and the most apppropriate way of installing it. .. _installation procedures: https://projects.unbit.it/uwsgi/wiki/Install Check again that you can still run uWSGI just like you did before: .. code-block:: bash uwsgi --ini mysite_uwsgi.ini # the --ini option is used to specify a file Emperor mode ------------ uWSGI can run in 'emperor' mode. In this mode it keeps an eye on a directory of uWSGI config files, and will spawn instances ('vassals') for each one it finds. Whenever a config file is amended, the emperor will automatically restart the vassal. .. code-block:: bash # create a directory for the vassals sudo mkdir -p /etc/uwsgi/vassals # symlink from the default config directory to your config file sudo ln -s /path/to/your/mysite/mysite_uwsgi.ini /etc/uwsgi/vassals/ # run the emperor uwsgi --emperor /etc/uwsgi/vassals --uid www-data --gid www-data You may need to run uWSGI with sudo: .. code-block:: bash sudo uwsgi --emperor /etc/uwsgi/vassals --uid www-data --gid www-data The options mean: * ``emperor``: where to look for vassals (config files) * ``uid``: the user id of the process once it's started * ``gid``: the group id of the process once it's started Check the site; it should be running. Make uWSGI startup when the system boots ---------------------------------------- The last step is to make it all happen automatically at system startup time. For many systems, the easiest (if not the best) way to do this is to use the ``rc.local`` file. Edit ``/etc/rc.local`` and add:: /usr/local/bin/uwsgi --emperor /etc/uwsgi/vassals --uid www-data --gid www-data --daemonize /var/log/uwsgi-emperor.log before the line "exit 0". And that should be it! Further configuration --------------------- It is important to understand that this has been a *tutorial*, to get you started. You **do** need to read the nginx and uWSGI documentation, and study the options available before deployment in a production environment. Both nginx and uWSGI benefit from friendly communities, who are able to offer invaluable advice about configuration and usage. nginx ^^^^^ General configuration of nginx is not within the scope of this tutorial though you'll probably want it to listen on port 80, not 8000, for a production website. You should also configure a separate nginx location block for serving non-Django files. For example, it's inefficient to serve static files via uWSGI. Instead, serve them directly from Nginx and completely bypass uWSGI. uWSGI ^^^^^ uWSGI supports multiple ways to configure it. See `uWSGI's documentation`_ and `examples`_. .. _uWSGI's documentation: https://uwsgi-docs.readthedocs.io .. _examples: https://projects.unbit.it/uwsgi/wiki/Example Some uWSGI options have been mentioned in this tutorial; others you ought to look at for a deployment in production include (listed here with example settings):: env = DJANGO_SETTINGS_MODULE=mysite.settings # set an environment variable safe-pidfile = /tmp/project-master.pid # create a pidfile harakiri = 20 # respawn processes taking more than 20 seconds limit-as = 128 # limit the project to 128 MB max-requests = 5000 # respawn processes after serving 5000 requests daemonize = /var/log/uwsgi/yourproject.log # background the process & log