server['request'] is basically an instantiation of HTTPRequest class. It gives you access to an HTTP request.
Here are some of interesting objects in addition to those in Headers and Cookies and Body and POST:
@app.route('/hello')
async def hello_world(request):
print('REMOTE_ADDR:', request.ip)
print('HTTP_HOST:', request.host)
print('REQUEST_METHOD:', request.method)
print('REQUEST_SCHEME:', request.scheme)
print('REQUEST_URI:', request.url)
print('PATH:', request.path)
print('QUERY:', request.query)
print('QUERY_STRING:', request.query_string)
print('VERSION:', request.version)
yield b'Hello'
yield b'World!'
print result on http://localhost:8000/hello?a=1&b=2
REMOTE_ADDR: b'127.0.0.1'
HTTP_HOST: b'localhost:8000'
REQUEST_METHOD: b'GET'
REQUEST_SCHEME: b'http'
REQUEST_URI: b'/hello?a=1&b=2'
PATH: b'/hello'
QUERY: {'a': ['1'], 'b': ['2']}
QUERY_STRING: b'a=1&b=2'
VERSION: b'1.1'
Note that Tremolo focuses on bytes-like, except in some dict objects like request.query, request.cookies, and request.form().
This is for maximum interoperability, to reduce the possibility of encoding - decoding back and forth, etc. With the tradeoff of being a bit inconvenient.
FYI, request.ip is not security wise. It will take the ip address from X-Forwarded-For / HTTP header when available.
It only becomes handy when Tremolo is deployed behind a proxy server, otherwise request.client[0] should be used.