Enhanced Service Gateway.
Introduction
ESG is a speed-oriented ASGI server implementation with HTTP/1.1 and WebSockets support.
Is a hard fork of the awesome uvicorn project.
Protocol implementation based on:
- llhttp - For HTTP payload
- http-parser - For URL parsing
- httptools - Clean and fast binding for the previous two. ESG Cython part development started from its forking.
Performance
Speed comparison ESG vs Uvicorn
PS > docker-compose run --rm bench-esg
Running 15s test @ http://esg:8000/
4 threads and 64 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 2.15ms 390.13us 9.51ms 92.82%
Req/Sec 7.47k 455.23 9.39k 68.00%
445749 requests in 15.01s, 66.32MB read
Requests/sec: 29694.49
Transfer/sec: 4.42MB
PS > docker-compose run --rm bench-uvicorn
Running 15s test @ http://uvicorn:8000/
4 threads and 64 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 4.03ms 0.85ms 16.28ms 91.16%
Req/Sec 3.99k 376.72 4.53k 82.67%
238272 requests in 15.01s, 36.36MB read
Requests/sec: 15874.17
Transfer/sec: 2.42MB
Quickstart
Install using pip
:
$ pip install esg[standard]
standart
extra will also install:
*If you want use wsproto instead of websockets you'd need to install it manually
Running simple ASGI application
Create an application, in example.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!',
'more_body': False
})
Run the server:
$ esg example:app
ASGI frameworks
Squall
Squall framework which looks ahead.
High performance API framework.
Starlette
Starlette is a lightweight ASGI framework/toolkit.
It is ideal for building high performance asyncio services, and supports both HTTP and WebSockets.
Django Channels
The ASGI specification was originally designed for use with Django Channels.
Channels is a little different to other ASGI frameworks in that it provides
an asynchronous frontend onto a threaded-framework backend. It allows Django
to support WebSockets, background tasks, and long-running connections,
with application code still running in a standard threaded context.
Quart
Quart is a Flask-like ASGI web framework.
FastAPI
FastAPI is an API framework based on Starlette and Pydantic, heavily inspired by previous server versions of APIStar.
You write your API function parameters with Python 3.6+ type declarations and get automatic data conversion, data validation, OpenAPI schemas (with JSON Schemas) and interactive API documentation UIs.
BlackSheep
BlackSheep is a web framework based on ASGI, inspired by Flask and ASP.NET Core.
Its most distinctive features are built-in support for dependency injection, automatic binding of parameters by request handler's type annotations, and automatic generation of OpenAPI documentation and Swagger UI.
Usage
The ESG command line tool is the easiest way to run your application...
Command line options
$ esg --help
Usage: esg [OPTIONS] APP
Options:
--host TEXT Bind socket to this host. [default:
127.0.0.1]
--port INTEGER Bind socket to this port. [default: 8000]
--uds TEXT Bind to a UNIX domain socket.
--fd INTEGER Bind to socket from this file descriptor.
--reload Enable auto-reload.
--reload-dir PATH Set reload directories explicitly, instead
of using the current working directory.
--reload-include TEXT Set glob patterns to include while watching
for files. Includes '*.py' by default; these
defaults can be overridden in `--reload-
exclude`.
--reload-exclude TEXT Set glob patterns to exclude while watching
for files. Includes '.*, .py[cod], .sw.*,
~*' by default; these defaults can be
overridden in `--reload-include`.
--reload-delay FLOAT Delay between previous and next check if
application needs to be. Defaults to 0.25s.
[default: 0.25]
--workers INTEGER Number of worker processes. Defaults to the
$WEB_CONCURRENCY environment variable if
available, or 1. Not valid with --reload.
--loop [auto|asyncio|uvloop] Event loop implementation. [default: auto]
--ws [auto|none|websockets|wsproto]
WebSocket protocol implementation.
[default: auto]
--ws-max-size INTEGER WebSocket max size message in bytes
[default: 16777216]
--ws-ping-interval FLOAT WebSocket ping interval [default: 20.0]
--ws-ping-timeout FLOAT WebSocket ping timeout [default: 20.0]
--lifespan [auto|on|off] Lifespan implementation. [default: auto]
--interface [auto|asgi3|asgi2|wsgi]
Select ASGI3, ASGI2, or WSGI as the
application interface. [default: auto]
--env-file PATH Environment configuration file.
--log-config PATH Logging configuration file. Supported
formats: .ini, .json, .yaml.
--log-level [critical|error|warning|info|debug|trace]
Log level. [default: info]
--access-log / --no-access-log Enable/Disable access log.
--use-colors / --no-use-colors Enable/Disable colorized logging.
--proxy-headers / --no-proxy-headers
Enable/Disable X-Forwarded-Proto,
X-Forwarded-For, X-Forwarded-Port to
populate remote address info.
--server-header / --no-server-header
Enable/Disable default Server header.
--date-header / --no-date-header
Enable/Disable default Date header.
--forwarded-allow-ips TEXT Comma seperated list of IPs to trust with
proxy headers. Defaults to the
$FORWARDED_ALLOW_IPS environment variable if
available, or '127.0.0.1'.
--root-path TEXT Set the ASGI 'root_path' for applications
submounted below a given URL path.
--limit-concurrency INTEGER Maximum number of concurrent connections to
allow, before issuing HTTP 503 responses.
--backlog INTEGER Maximum number of connections to hold in
backlog
--limit-max-requests INTEGER Maximum number of requests to service before
terminating the process.
--timeout-keep-alive INTEGER Close Keep-Alive connections if no new data
is received within this timeout. [default:
5]
--ssl-keyfile TEXT SSL key file
--ssl-certfile TEXT SSL certificate file
--ssl-keyfile-password TEXT SSL keyfile password
--ssl-version INTEGER SSL version to use (see stdlib ssl module's)
[default: 17]
--ssl-cert-reqs INTEGER Whether client certificate is required (see
stdlib ssl module's) [default: 0]
--ssl-ca-certs TEXT CA certificates file
--ssl-ciphers TEXT Ciphers to use (see stdlib ssl module's)
[default: TLSv1]
--header TEXT Specify custom default HTTP response headers
as a Name:Value pair
--version Display the esg version and exit.
--app-dir TEXT Look for APP in the specified directory, by
adding this to the PYTHONPATH. Defaults to
the current working directory. [default: .]
--factory Treat APP as an application factory, i.e. a
() -> <ASGI app> callable. [default: False]
--help Show this message and exit.
Running programmatically
To run ESG directly from your application
example.py:
import esg
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!',
'more_body': False
})
if __name__ == "__main__":
esg.run("example:app", host="127.0.0.1", port=5000, log_level="info")
Running with Gunicorn
Gunicorn is a mature, fully featured server and process manager.
ESG includes a Gunicorn worker class allowing you to run ASGI applications,
with all of ESG's performance benefits, while also giving you Gunicorn's
fully-featured process management.
This allows you to increase or decrease the number of worker processes on the
fly, restart worker processes gracefully, or perform server upgrades without downtime.
For production deployments we recommend using gunicorn with the ESG worker class.
gunicorn example:app -w 4 -k esg.workers.ESGWorker
For more information, see the deployment documentation.
Application factories
The --factory
flag allows loading the application from a factory function, rather than an application instance directly. The factory will be called with no arguments and should return an ASGI application.
example.py:
def create_app():
app = ...
return app
$ esg --factory example:create_app
The ASGI interface
ESG uses the ASGI specification for interacting with an ASGI application.
The application should expose an async callable which takes three arguments:
scope
- A dictionary containing information about the incoming connection.receive
- A channel on which to receive incoming messages from the server.send
- A channel on which to send outgoing messages to the server.
Two common patterns you might use are either function-based applications:
async def app(scope, receive, send):
assert scope['type'] == 'http'
...
Or instance-based applications:
class App:
async def __call__(self, scope, receive, send):
assert scope['type'] == 'http'
...
app = App()
It's good practice for applications to raise an exception on scope types
that they do not handle.
The content of the scope
argument, and the messages expected by receive
and send
depend on the protocol being used.
The format for HTTP messages is described in the ASGI HTTP Message format.
HTTP Scope
An incoming HTTP request might have a connection scope
like this:
{
'type': 'http.request',
'scheme': 'http',
'root_path': '',
'server': ('127.0.0.1', 8000),
'http_version': '1.1',
'method': 'GET',
'path': '/',
'headers': [
[b'host', b'127.0.0.1:8000'],
[b'user-agent', b'curl/7.51.0'],
[b'accept', b'*/*']
]
}
HTTP Messages
The instance coroutine communicates back to the server by sending messages to the send
coroutine.
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!',
})
Requests & responses
Here's an example that displays the method and path used in the incoming request:
async def app(scope, receive, send):
"""
Echo the method and path back in an HTTP response.
"""
assert scope['type'] == 'http'
body = f'Received {scope["method"]} request to {scope["path"]}'
await send({
'type': 'http.response.start',
'status': 200,
'headers': [
[b'content-type', b'text/plain'],
]
})
await send({
'type': 'http.response.body',
'body': body.encode('utf-8'),
})
Reading the request body
You can stream the request body without blocking the asyncio task pool,
by fetching messages from the receive
coroutine.
async def read_body(receive):
"""
Read and return the entire body from an incoming ASGI message.
"""
body = b''
more_body = True
while more_body:
message = await receive()
body += message.get('body', b'')
more_body = message.get('more_body', False)
return body
async def app(scope, receive, send):
"""
Echo the request body back in an HTTP response.
"""
body = await read_body(receive)
await send({
'type': 'http.response.start',
'status': 200,
'headers': [
[b'content-type', b'text/plain'],
]
})
await send({
'type': 'http.response.body',
'body': body,
})
Streaming responses
You can stream responses by sending multiple http.response.body
messages to
the send
coroutine.
import asyncio
async def app(scope, receive, send):
"""
Send a slowly streaming HTTP response back to the client.
"""
await send({
'type': 'http.response.start',
'status': 200,
'headers': [
[b'content-type', b'text/plain'],
]
})
for chunk in [b'Hello', b', ', b'world!']:
await send({
'type': 'http.response.body',
'body': chunk,
'more_body': True
})
await asyncio.sleep(1)
await send({
'type': 'http.response.body',
'body': b'',
})
Alternative ASGI servers
Uvicorn
The most famous ASGI server. ESG development started from hard-forking of exactly Uvicorn.
Uvicorn has a clean codebase and superior fast performance.
$ pip install uvicorn
$ uvicorn app:App
Daphne
The first ASGI server implementation, originally developed to power Django Channels, is the Daphne webserver.
It is run widely in production, and supports HTTP/1.1, HTTP/2, and WebSockets.
Any of the example applications given here can equally well be run using daphne
instead.
$ pip install daphne
$ daphne app:App
Hypercorn
Hypercorn was initially part of the Quart web framework, before
being separated out into a standalone ASGI server.
Hypercorn supports HTTP/1.1, HTTP/2, and WebSockets.
$ pip install hypercorn
$ hypercorn app:App
Roadmap
- Better security setting.
- Header timeout
- Body timeout (timeout between calling receive and data arrive)
- Headers size limit
- Request body size limit
- Statistic
- Cythonized WebSocket protocol