daphne/README.rst

daphne
======

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Daphne is a HTTP, HTTP2 and WebSocket protocol server for
`ASGI <https://channels.readthedocs.io/en/latest/asgi.html>`_, and developed
to power Django Channels.

It supports automatic negotiation of protocols; there's no need for URL
prefixing to determine WebSocket endpoints versus HTTP endpoints.


Running
-------

Simply point Daphne to your ASGI channel layer instance, and optionally
set a bind address and port (defaults to localhost, port 8000)::

    daphne -b 0.0.0.0 -p 8001 django_project.asgi:channel_layer

If you intend to run daphne behind a proxy server you can use UNIX
sockets to communicate between the two::

    daphne -u /tmp/daphne.sock django_project.asgi:channel_layer

If daphne is being run inside a process manager such as
`Circus <https://github.com/circus-tent/circus/>`_ you might
want it to bind to a file descriptor passed down from a parent process.
To achieve this you can use the --fd flag::

    daphne --fd 5 django_project.asgi:channel_layer

If you want more control over the port/socket bindings you can fall back to
using `twisted's endpoint description strings
<http://twistedmatrix.com/documents/current/api/twisted.internet.endpoints.html#serverFromString>`_
by using the `--endpoint (-e)` flag, which can be used multiple times.
This line would start a SSL server on port 443, assuming that `key.pem` and `crt.pem`
exist in the current directory (requires pyopenssl to be installed)::

    daphne -e ssl:443:privateKey=key.pem:certKey=crt.pem django_project.asgi:channel_layer

Endpoints even let you use the ``txacme`` endpoint syntax to get automatic certificates
from Let's Encrypt, which you can read more about at http://txacme.readthedocs.io/en/stable/.

To see all available command line options run daphne with the *-h* flag.


HTTP/2 Support
--------------

Daphne 1.1 and above supports terminating HTTP/2 connections natively. You'll
need to do a couple of things to get it working, though. First, you need to
make sure you install the Twisted ``http2`` and ``tls`` extras::

    pip install -U Twisted[tls,http2]

Next, because all current browsers only support HTTP/2 when using TLS, you will
need to start Daphne with TLS turned on, which can be done using the Twisted endpoint syntax::

    daphne -e ssl:443:privateKey=key.pem:certKey=crt.pem django_project.asgi:channel_layer

Alternatively, you can use the ``txacme`` endpoint syntax or anything else that
enables TLS under the hood.

You will also need to be on a system that has **OpenSSL 1.0.2 or greater**; if you are
using Ubuntu, this means you need at least 16.04.

Now, when you start up Daphne, it should tell you this in the log::

    2017-03-18 19:14:02,741 INFO     Starting server at ssl:port=8000:privateKey=privkey.pem:certKey=cert.pem, channel layer django_project.asgi:channel_layer.
    2017-03-18 19:14:02,742 INFO     HTTP/2 support enabled

Then, connect with a browser that supports HTTP/2, and everything should be
working. It's often hard to tell that HTTP/2 is working, as the log Daphne gives you
will be identical (it's HTTP, after all), and most browsers don't make it obvious
in their network inspector windows. There are browser extensions that will let
you know clearly if it's working or not.

Daphne only supports "normal" requests over HTTP/2 at this time; there is not
yet support for extended features like Server Push. It will, however, result in
much faster connections and lower overheads.

If you have a reverse proxy in front of your site to serve static files or
similar, HTTP/2 will only work if that proxy understands and passes through the
connection correctly.


Root Path (SCRIPT_NAME)
-----------------------

In order to set the root path for Daphne, which is the equivalent of the
WSGI ``SCRIPT_NAME`` setting, you have two options:

* Pass a header value ``Daphne-Root-Path``, with the desired root path as a
  URLencoded ASCII value. This header will not be passed down to applications.

* Set the ``--root-path`` commandline option with the desired root path as a
  URLencoded ASCII value.

The header takes precedence if both are set. As with ``SCRIPT_ALIAS``, the value
should start with a slash, but not end with one; for example::

    daphne --root-path=/forum django_project.asgi:channel_layer

Dependencies
------------

All Channels projects currently support Python 2.7, 3.4 and 3.5. `daphne` requires Twisted 17.1 or
greater.


Contributing
------------

Please refer to the
`main Channels contributing docs <https://github.com/django/channels/blob/master/CONTRIBUTING.rst>`_.
That also contains advice on how to set up the development environment and run the tests.


Maintenance and Security
------------------------

To report security issues, please contact security@djangoproject.com. For GPG
signatures and more security process information, see
https://docs.djangoproject.com/en/dev/internals/security/.

To report bugs or request new features, please open a new GitHub issue.

This repository is part of the Channels project. For the shepherd and maintenance team, please see the
`main Channels readme <https://github.com/django/channels/blob/master/README.rst>`_.