Granian

A Rust HTTP server for Python applications.

Rationale

The main reasons behind Granian design are:

• Have a single, correct HTTP implementation, supporting versions 1, 2 (and eventually 3)
• Provide a single package for several platforms
• Avoid the usual Gunicorn + uvicorn + http-tools dependency composition on unix systems
• Provide stable performance when compared to existing alternatives

Features

• Supports ASGI/3, RSGI and WSGI interface applications
• Implements HTTP/1 and HTTP/2 protocols
• Supports HTTPS
• Supports Websockets over HTTP/1 and HTTP/2

Quickstart

You can install Granian using pip:

$ pip install granian

Create an ASGI application in your main.py:

async def app(scope, receive, send):
    assert scope['type'] == 'http'

    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [
            [b'content-type', b'text/plain'],
        ],
    })
    await send({
        'type': 'http.response.body',
        'body': b'Hello, world!',
    })

and serve it:

$ granian --interface asgi main:app

You can also create an app using the RSGI specification:

async def app(scope, proto):
    assert scope.proto == 'http'

    proto.response_str(
        status=200,
        headers=[
            ('content-type', 'text/plain')
        ],
        body="Hello, world!"
    )

and serve it using:

$ granian --interface rsgi main:app

Options

You can check all the options provided by Granian with the --help command:

$ granian --help
Usage: granian [OPTIONS] APP

Arguments:
  APP  Application target to serve.  [required]

Options:
  --host TEXT                     Host address to bind to.  [env var:
                                  GRANIAN_HOST; default: 127.0.0.1]
  --port INTEGER                  Port to bind to.  [env var: GRANIAN_PORT;
                                  default: 8000]
  --interface [asgi|rsgi|wsgi]    Application interface type.  [env var:
                                  GRANIAN_INTERFACE; default: rsgi]
  --http [auto|1|2]               HTTP version.  [env var: GRANIAN_HTTP;
                                  default: auto]
  --ws / --no-ws                  Enable websockets handling  [env var:
                                  GRANIAN_WEBSOCKETS; default: (enabled)]
  --workers INTEGER RANGE         Number of worker processes.  [env var:
                                  GRANIAN_WORKERS; default: 1; x>=1]
  --threads INTEGER RANGE         Number of threads.  [env var:
                                  GRANIAN_THREADS; default: 1; x>=1]
  --threading-mode [runtime|workers]
                                  Threading mode to use.  [env var:
                                  GRANIAN_THREADING_MODE; default: workers]
  --loop [auto|asyncio|uvloop]    Event loop implementation  [env var:
                                  GRANIAN_LOOP; default: auto]
  --opt / --no-opt                Enable loop optimizations  [env var:
                                  GRANIAN_LOOP_OPT; default: (disabled)]
  --backlog INTEGER RANGE         Maximum number of connections to hold in
                                  backlog.  [env var: GRANIAN_BACKLOG;
                                  default: 1024; x>=128]
  --log / --no-log                Enable logging  [env var:
                                  GRANIAN_LOG_ENABLED; default: (enabled)]
  --log-level [critical|error|warning|warn|info|debug]
                                  Log level  [env var: GRANIAN_LOG_LEVEL;
                                  default: info]
  --log-config FILE               Logging configuration file (json)  [env var:
                                  GRANIAN_LOG_CONFIG]
  --ssl-keyfile FILE              SSL key file  [env var: GRANIAN_SSL_KEYFILE]
  --ssl-certificate FILE          SSL certificate file  [env var:
                                  GRANIAN_SSL_CERTIFICATE]
  --url-path-prefix TEXT          URL path prefix the app is mounted on  [env
                                  var: GRANIAN_URL_PATH_PREFIX]
  --reload / --no-reload          Enable auto reload on application's files
                                  changes  [env var: GRANIAN_RELOAD; default:
                                  no-reload]
  --version                       Shows the version and exit.
  --install-completion [bash|zsh|fish|powershell|pwsh]
                                  Install completion for the specified shell.
                                  [env var: GRANIAN_INSTALL_COMPLETION]
  --show-completion [bash|zsh|fish|powershell|pwsh]
                                  Show completion for the specified shell, to
                                  copy it or customize the installation.  [env
                                  var: GRANIAN_SHOW_COMPLETION]
  --help                          Show this message and exit.

Threading mode

Granian offers two different threading paradigms, due to the fact the inner Rust runtime can be multi-threaded – in opposition to what happens in Python event-loop which can only run as a single thread.

Given you specify N threads with the relevant option, in workers threading mode Granian will spawn N single-threaded Rust runtimes, while in runtime threading mode Granian will spawn a single multi-threaded runtime with N threads.

Benchmarks suggests workers mode to be more efficient with a small amount of processes, while runtime mode seems to scale more efficiently where you have a large number of CPUs. Real performance will though depend on specific application code, and thus your mileage might vary.

Event loop optimizations

With the --opt option Granian will use custom task handlers for Python coroutines and awaitables to improve Python code execution. Due to the nature of such handlers some libraries and specific application code relying on asyncio internals might not work.

You might test the effect such optimizations cause over your application and decide wether to enable 'em or leave 'em disabled (as per default).

Project status

Granian is currently under active development.

Granian is compatible with Python 3.8 and above versions.

License

Granian is released under the BSD License.